THURSDAY, April 1, 2004

Session 3: Neuroscience, Brain, and Behavior II: Emotional and Cognitive Development in Children

Jerome Kagan, Ph.D.,
Daniel and Amy Starch Research Professor of Psychology, Harvard University

Elizabeth S. Spelke, Ph.D.,
Professor of Psychology, Harvard University

CHAIRMAN KASS:  This afternoon's session, the first of two, is titled "Neuroscience, Brain, and Behavior II:  Emotional and Cognitive Development in Children."  And I've been asked to say at least a sentence or two about, well, to be blunt, what's going on here.  This will not be long, and we'll have more to say about what's going on here in the last session when we're talking amongst ourselves, but I remind everybody that the purpose of today's session agreed to last time was that before we took up and searched for various ethical or social or philosophical issues raised by advances in neuroscience and psychology, we ought to learn some of the basic facts.

And the purpose of these discussions is to lay the groundwork for anything further that we would do.  The morning was on the neuroscience.  This afternoon is on the side of psychology.

There are no axes here, and there are no agendas, other than getting us informed about the current state of knowledge about the developing brain and the developing mind and behavior of children.  So if anybody is impatient, just soak up this knowledge.  It's terrific stuff.

The relation of the brain and the mind, of the activities of molecules and synapses to mentation, never mind consciousness, is, as everybody knows, a venerable question, a deep philosophical issue that has occupied and vexed and challenged the best minds since classical antiquity, and one simply has to mention the names of Lucretius and Aristotle to show you how old these controversies are.  There are idealists; there are dualists; there are compatiblists; there are  epiphenomenalists.

Yet even as those sort of prize questions continue to be discussed and debated, even people who are committed to fully neurochemical and mechanistic account of all mental and behavioral activity recognize the prime importance of studying the mental and behavioral phenomena in their own right and on their own level, leaving for later any attempts to connect the domains of psychology, the study of the psyche, and the domain of neuroscience, the science of the brain.

So with no prejudice regarding this deferred questions about the relation of mind and behavior to the brain, we also want to know not only about the neural development, normal development of the brain and nervous system in children, but the normal and also abnormal development in all of its variations of the emotional and temperamental side of human development, and of the cognitive capacities and activities of children, and that is the theme for this afternoon's discussion, and we're very fortunate to have two colleagues from Harvard's Department of Psychology, Jerome Kagan, who is the Daniel and Amy Starch Research Professor of Psychology at Harvard University, and Elizabeth Spelke, who is Professor of Psychology, also at Harvard University.

Dr. Kagan is going to speak about  the temperament and affective side, and Professor Spelke will speak about the cognitive side, and I think the procedure is we will let each of them make their presentations, perhaps with small questions of clarification after each talk, and then the general discussion will follow.

Thank you both very much for coming down and being with us, and we're delighted to have you here and look forward to the presentations.

Professor Kagan, would you like to start?

PROFESSOR KAGAN:  Yes.  Can you hear?

Thank you very much for inviting me, and let me also follow Professor Jessell's suggestion that interrupt me if there are any questions that you have during the presentation.

And I promise to hold it to 40 minutes, ten of three, so that you can hear Dr. Spelke and have time for discussion.

Unlike the area you heard this morning, the growth of the brain, which is, you know, mid-volume, the systematic work on human temperament is about 50 years old.  Since American psychology was committed to a behaviorism that did not want to acknowledge biology, and although there have been many essays going back to Hippocrates on temperament, there is no empirical work.

So this is a field that is in Chapter 1, and therefore, we can't show off the wonderful findings you heard this morning, but we can give you a scaffolding.

Also, you should appreciate that in biology when a speaker says "dendrite," everybody knows what he means.  But when you get to psychological concepts, people have different understandings, and so I will try to give you the understanding that I'm using.  Remember the meaning of words, as Virginia Wolf said, is a function of how they're used.

So the concept of temperament as it is used today in the Western world means variation within humans in mood and behavior that is biologically based.  My own view is that it should be restricted to inherited variation, but there are those who say any variation, even variation caused prenatally.

Now, the analogy would be we talk about breed differences in dogs.  So some people like Rhodesian ridgebacks.  Some people like cocker spaniels.  They belong to the same species.  Their behaviors are different, and we say those are breed differences.

When we talk about humans, that is the domain we're talking about, but we use the word "temperament."  My own view is that most of the temperamental variation—one should never say "all" in the life sciences—that most of the temperamental variation will be due to inherited differences in neurochemistry.  There are over 150 molecules discovered.  Many more may be discovered.  We all have the same molecules, but we differ in their concentrations, and we differ in the density receptors, those proteins that sit on the neurons.  How dense are those receptors.

And we differ in the distribution of those receptors.  Thomas Insel, who now is the Director of NIMH, provides us with a perfect example of what we mean by a neurochemical variation that causes a big difference in behavior.  So let me use it, and it will help you understand the work on humans.

The vole is a very small rodent.  It looks like a mouse.  Now, there's one strain of voles called prairie voles.  They pair bond.  Once the male and female mate for six hours they will never mate again with anyone else.

The montane vole that shares 99.99 percent of its genes with the prairie vole doesn't pair bond.  Now, that is a dramatic difference in behavior, and Insel in 20 years of really elegant research finds that the main cause of that difference is a change.

Remember a gene is a strip of DNA, but in front of each gene is an area called the promoter region which governs the DNA.  Well, in the promoter region for two molecules, one is called vasopressin and the other is called oxytocin, secreted during sexual intercourse incidentally, both of these molecules; that that explains the difference.

So tiny, tiny genetic differences, not even in the DNA, but in the promoter region for the DNA.

Now, I wish I could tell a story.  Here are some of the molecules, and remember there are over 150.  At the moment they look relevant.  So children could be born with differences in opioid concentrations or the receptors for opioids.

For example, right here in our neck is the structure called the medulla.  All pain, information from your heart and gut come up through your body, and they have to pass through that gateway.

Well, supposed some individual was born with a light set of receptors for opioids.  Then they would experience pain and muscle strain more easily than others.

GABA is an inhibitory molecule prevalent throughout the entire brain and its job is to mute excitability.  I'm going to say in a moment that some infants are very irritable, extremely irritable.  It looks like a temperamental trait that expresses itself in certain behaviors later in life.

It could be that what these children inherit, these very irritable infants is a failure, a compromised function in GABA.

Dopamine is a powerful molecule.  Every time any one of us anticipate a trip, a holiday, a good meal tonight at 6:30, dopamine pours out of our central nervous system.  When a rat is about to get food it wants, it pours out dopamine from its source in the brain.

Now, individuals, and it is believed by many that there's a subtle surge of pleasure when one is looking forward to seeing Rome for the first time and you're there.  People differ in their hedonic tone, in the amount of pleasure they take from experience.  It is not beyond reason that someone some day will find that dopamine is playing a role.

Notice there's no determinism here.  I'm going to use words like "enable," "determine a role," "contribute to."

Norepinephrine is a very important molecule.  If you're listening hard for a signal that your wife is coming home because it's midnight.  Norepinephrine acts on sensory neurons so that you hear the signal you're interested in and not the noise or when you're trying to hear a conversation several feet away.  So children are extremely vigilant to change, any subtle change, and some children seem oblivious.  Perhaps norepinephrine makes a contribution there.

And finally, just to have a flavor for these, corticotropin releasing hormone is often secreted but not always when one is under stress, and I'm sure most of you know that all of us when we're under stress secrete a small hormone called cortisol from our adrenal cortex, and variation in corticotropin releasing hormone could play a role here.

Now, I wish we could go to a book and look up everything we've learned about neurochemistry and now talk about human temperaments.  One day, but not today.

So those of us who study temperaments must begin with behavior.  That would be like medicine 250 years ago when one knew nothing about what's happening in the immune system, and so the patient tells you, "I have an ache in my body.  I itch in my arm," and so on.  You go to the surface, and one day, of course, we will tie together the behavior with the biology.

Now, many psychologists have been studying the temperamental traits, and here are four that look like they might be temperamental, that is, due to inherited variation in this neurochemistry.

I mentioned irritability.  Some infants are extremely irritable, and the data indicate that that persisted the first year.  Now, you stop being extremely irritable when you're one and two years of age, but investigators who have followed such infants find that they are different at five, six, and seven years of age.  Some children are very active and show very high levels of muscle tension, and we'll be talking about that in a moment.

Believe it or not, in the first six months some infants smile a lot, and you'll see in about ten minutes I regard this as a very powerful temperamental trait in humans.  Children who smile a lot in the first six months spontaneously tend to preserve a more sanguine view of life through adolescence.  Some infants don't smile at all.   As a matter of fact, in the laboratory they'll show a frown on their face, and they tend to be more pessimistic children later in life.

Now, in order to concretize this discussion, let's tell two stories.  I'm going to tell you one story.  It's the story that I've been writing for 25 years, but it only reflects two temperaments of the many.  There are going to be thousands of temperaments.

If there are 150 molecules and they vary in their concentration and receptor density, remember from your algebra how many combinations of 150 things you can have.  There are going to be millions of temperaments, and even if half were not functional, you're going to have a very large number, some being very rare like the Unabomber or Mozart, and some more common.

I'm going to talk about two common temperaments only because the work on them is more extensive than others, and they're relatively frequent, but not that they are necessarily the most important temperaments, and it has to do with reaction to unfamiliarity.

In every vertebrate species, within every vertebrate species, fish, birds, cats, mice, monkeys, and of course, humans, there are some members that react to novelty and unfamiliarity by become immobile if you're an animal, freezing if you're a rat, not exploring an unfamiliar area if you're a mouse or if you're a child, closing down and exploring the situation before you assimilate it and move forward.

And other children are just the opposite.  Now, in animals, this is extremely heritable.  You can breed it.  You can breed quail, rats, mice, and Steve Suomi of NIH believes even breed monkeys so that after 20 generations you have either very timid or very bold monkeys, mice or rats.

Now, it is believed by the work of many scientists that deserve a great deal of credit, it looks like the amygdala, which is a small structure right in back of your temporal lobe, tiny, shape of an almond.  It's very important because whenever you present novel stimuli to any animal and you record from neurons in the amygdala, those neurons respond.

And so if you presented a novel event to a monkey and you had electrodes down the amygdala, it would respond, but if you kept on presenting the stimulus, the neurons would stop responding.  The amygdala response is a novelty, and you can see why this is important.

You're a monkey out in the savannah, and you're munching your bananas, and suddenly an odd sound occurs.  The amygdala fire, makes you alert, and then you decide whether you're going to flee or it's an unimportant event and you keep on eating your bananas.

Now, I have been interested for many years in timid versus bold children, and so to abbreviate ten or 15 years of work, we decided that perhaps these were temperamental traits traceable to infancy, and so we began a study of 500 healthy, middle class, four month old infants.

Now, why did I restrict it?  Because if you want to study temperament, you have to eliminate all of the other causes of possible timidity:  a mother took drugs during her pregnancy; drank too much; smoked cigarettes; drank coffee.  And so you want mothers who cared about their pregnancy and gave birth to healthy babies at term.

That means that if one did the study I'm about to describe on infants born to compromised pregnancies we might get different results.  Okay?  So these are healthy babies born at term.

Now, the reason why the amygdala is important is that if you stimulate the amygdala of a cat or a monkey, you get limb movements and you get distress cries, and of course, human infants will display those two responses.

So here is the central idea behind the work.  This is a schematic of the amygdala.  Vision audition and touch come into this area of the amygdala, send their information up to this nucleus, and then out to the body to produce tension, immobility, a rise in heart rate, a rise in blood pressure or other biological consequences.

Assumption:  if some infants were born with a chemistry unknown at the moment that rendered the amygdala excitable to unfamiliar events, then they should show a lot of motor activity and crying when you present these unfamiliar events.  If you were born with a different chemistry, then you should show low motor activity and not be very distressed, and we call those infants high and low reactive.

So after testing 500 infants by showing them unfamiliar mobiles of different colored elements moving in front of them, listening to speech on a tape with sentences like, "Hello, baby.  How are you today.  Thank you very much for coming," or presenting a cotton swab dipped in butyl alcohol to their nostril, olfactory, auditory, visual, what you see is that 20 percent of the babies are very different from all other babies.   They begin to thrash.  They arch their backs.  They become very aroused motorically and cry.  They should have a more excitable amygdala.

Forty percent, twice as much, are just the opposite.  They don't move.  They lie there.  They move an arm.  They don't cry.

Now we call the first group high reactive and the second group low reactive, and now briefly I'm going to show you what happens if you follow these infants through 11 years of age.  Okay?

So you bring these infants back at 14 and 21 months for two hours with their mother and they encounter unfamiliar events.  Nothing threatening, no snakes, no mice, just people they don't know, a clown, people dressed in clown costumes, robots that move, novel events that are not obviously dangerous.

Some children do not become very frightened.  Some cry and clutch their mother.  I didn't bring my laser so if you follow me, you see the high reactives are in the light color, the low reactives in the dark purple.  So at 14 months those who are high reactive at four months were more fearful.  At 21 months they were more fearful. 

At seven and a half years the IRB of the university, in order to make children cry, you have to do things that are unethical.  So we don't do that.

Now, with age what happens is that these traits become internalized, and so rather than cry you begin to show the traits of the introvert.  You don't smile or talk easily with a stranger.  So if you're interviewed by an examiner for two hours, you talk less.  You see at seven and a half years you smile less.

You remember I said that smiling is very sensitive, and based on observations of children and interviews with the mothers and the teachers, you're more likely to have anxious symptoms.  Now, notice I'm not calling this child as having an anxiety disorder.  This is a child who doesn't want to sleep over at a friend's house, needs night light on, asks their mother will they be kidnapped, is their mother going to die.  They're afraid of large dogs or insects.

And you'll see that 45 percent of this group who are high reactive had anxious symptoms.  Remember only 20 percent of the group was high reactive.  So that's twice as many as you'd expect.  Only ten percent of low reactives had symptoms, while 40 percent of the sample.  So that's much less than you would expect.

So these children are developing in a way that one would anticipate, given the assumption about their amygdala.  Okay?

Now, by the time they're 11 years of age, a lot of them aren't shy anymore.  What happens with increasing age is that you get an increasing dissociation between your behavior, what you have called your persona, and what's going on inside.  Your grandmother knew it as "don't judge a book by its cover."

But we believe that they retain their biology.  So we have to measure their biology, and I apologize for doing this quickly.

There are four measures that based on the research of many scientists one would reasonably assume should characterize the high reactive children at 11 years, but not the low reactives, and they are:  One is to have greater activation in the right hemisphere than the left.  For example, if you take a newborn baby and put lemon juice on its tongue, you get right hemisphere activation.  If you put sugar water on its tongue, you left hemisphere activation.

Now, there are exceptions here, but as a rough rule the right hemisphere is more active under states of uncertainty and adversiveness, the left hemisphere under the complimentary state.  So we measured that using EEG.

Let's do the behavior first.  When they come in at 11 years of age, we watch their behavior, and if we combine their behavior at seven years and ten years of age, and here's the important result, 40 percent of the children who had been high reactive made many low comments.  You see the turquoise blue bar on the left, and very low smiles, 40 percent, while less than ten percent of the low reactives did.

While if you said who talked and smiled a great deal, it's just the opposite.  So, in other words, temperament constrains what you will become.  Forty percent are honest to their early temperament, but only six or seven percent cross over.  So that means temperament doesn't determine what you will be, but its power is to prevent a high reactive infant from becoming an extremely social, exuberant child, while a low reactive temperament constrains that child from becoming an extremely timid and subdued child.  We'll return to this in a moment.

Now, here are the data on hemisphere activation.  The high reactives are in pink, and the low reactives in yellow, and on the left side of the graph is showing right hemisphere activation, and on the right side of the graph is left hemisphere activation.  So follow the pink line, and you'll see that 43 percent of the high reactives showed greater right hemisphere activation, and as you move towards the left fewer and fewer high reactives, while the yellow line, only 18 percent of low reactives were right hemisphere active and they moved up. 

So there's the first prediction.  AT 11 years of age, you can do better than chance at predicting hemisphere activation at 11 years of age from what they were like at four months.

Now, the next measure is more direct.  In the system for hearing, when you hear any sound it goes through a series of ganglia, first your basilar membrane in your ear.  Then it goes through a series of nuclei and ends up in the mid-brain in a structure called the inferior colliculus.

And if you present clicks to an infant or a child, if you get a series of brain waves from those clicks, every infant in Massachusetts is tested this way to insure that it can hear.  Now, notice pk V.  That is the evoke potential from the inferior colliculus.  It occurs in about six milliseconds.

Now, here's why that's important.  The amygdala, our friendly amygdala, sends projections down to the colliculus, pk V, but not to any other structure before it, and that means that if you had an excitable amygdala, you should show a larger pk V, a larger wave V than if you were a low reactive.

I hope that's clear.  So the 11 year olds wore earphones, and they heard clicks for 90 seconds, and sure enough, as we expected, the children who had been high reactive at four months had large wave forms, especially when the loudness was 70 decibels and you were measuring it on the opposite side of where the information came in. 

So there's our second prediction, and that one does support the notion that high reactives have a more excitable amygdala.

The third, many scientists over the last 35 years have made an important discovery.  Whenever you're presented with a visual or auditory event that surprises you, you have a very distinctive wave form.  If you were sitting in a laboratory with EEG electrodes on and you heard the following, "Washington, D.C. is a vegetable," that on the word "vegetable," you would have a wave form like that.

But if you heard "Washington, D.C. is a city," there would be no wave formed.  So whenever you're surprised by an event you don't expect, you get a very distinctive wave form.

Now, remember what I said about high reactive infants.  They are very sensitive to unexpected events.  So we then hope to see that at 11 years of age, the high reactives would show larger, evoke larger event related potentials as you saw in the last slide to scenes that were totally unfamiliar.

Go to the far right where it says "invalid."  These are ecologically invalid scenes, none of which are dangerous.  For example, a baby's head on an animal's body or a car in midair or a chair on one leg.

While for the frequent, if you go over to the far left where it says "frequent," that's a fire hydrant being shown 70 percent of 169 trials. 

So there's our third prediction affirmed.  Right hemisphere activation, a larger wave V, and a large event related potential to surprising scenes.

And the last measure, the amygdala sends projections to the sympathetic nervous system, and therefore, one should show greater sympathetic tone in the cardiovascular system, and we measured that in several ways, and so the term sympathetic means that you have greater priming of the circulatory vessels and the heart, while the vagal system means you have less priming because it is mediated by the parasympathetic system, and as you can see, about 65 percent of the high reactives at age 11 were sympathetic compared with about 38 percent of the low reactives and the opposite for vagal tone.

Now, let's put it together.  A temperamental bias constrains what you will become.  Let me skip that, and here is the final line.  About one in four high reactives and one in four low reactives combined expected behavior with biology versus one of 20 who do not.

That means that if outside that door there were 100 adults and I said—they're 20 years old—I said they're high reactive infants, every one of them.  If I predict that they will not be exuberant, bold, highly sociable 20 year olds who show right hemisphere—they wouldn't show right hemisphere activation; they wouldn't show a big wave V; they wouldn't show sympathetic tone; I'm going to be right 95 percent of the time.

If you say they're going to be quiet introverts who have high sympathetic tone in a large wave V, you'll be right 20 percent of the time.

And of course, the same thing shows for the environment.  If I say, "I have this beautiful girl born to nurturing parents in a lovely suburb of Boston who went to good schools, she's 25 years old.  Tell me about her," you will be more correct if you what she is not.

She's probably not a drug addict.  She's probably not a prostitute.  She's probably not on welfare, but what else?  Who did she marry?  What did she major in?  What will she do?  You have no idea.

And that's an important message which we have in psychology, tend to think of the environment and biology as deterministic, and we should begin to think of it rather as constraining rather than deterministic.

Because of time, let me go to some of the implications because I don't want to take much time from Professor Spelke.  Here are some implications.

Individuals with similar public profiles can differ in the origins of those profiles.  Current psychiatry, 99 percent of all you read in the papers about the epidemiology of psychiatric illness is based only on interviews.  They never assess the biology of the person.

And so two people can say that they worry.  They're worried about the war or they're worried about terrorists, but one person has an extreme emotional reaction, and once psychiatrists begin to add not necessarily these measures, biological measures to the interview, then you will see all of the prevalence figures for mental illness change because right now they're based on one source of evidence.

Second, the ancients understood a temperamental bias does not imply that will is impotent with respect to a behavior.  Remember the ancients said that temperaments control your mood.  They don't control your action. 

So I can feel anxious, but I can control my tendency to avoid.  I can feel angry easily, but I can control my impulse to strike, and so on.  And so we're in a dangerous period because biological determinism is so popular in having the public believe, well, after all, if this is genetic, then why should I be held responsible for my behavior.

The third implication will come in about 20 or 25 years from now because there will be variation in temperaments across reproductively isolated populations.  When mutations occur and they change the shape of your eyes, the color of your hair, whether you're vulnerable to spina bifida or not, nature doesn't stop there.  Obviously the genes that separate reproductively isolated populations are going to affect the neurochemistry, too, and so we're going to discover in a quarter century that there are temperamental differences among Asians, Africans, aborigines of Australia, Europeans.  No question about it.

Although the work is preliminary, it is pretty clear now that Asian and European infants differ dramatically.  There are three studies:  Daniel G. Freedman, Caudill, Michael Lewis, my own.

Asian infants tend to be very low arousal, whether they are born in America or born in Beijing, while European infants are much more active, more easily distressed, and those look like temperamental differences, and I'm sure when we are less self-conscious—unfortunately we are—about ethnic differences, right now it's focused unfortunately on school performance and IQ and that will vanish, but there will be temperamental differences.  I think that the benevolent consequence of that is that we'll recognize that every reproductively isolated group, as is true for humans, is true for animals, has a special set of advantages and a special set of disadvantages, and that's the way it goes, and that will be, I think, beneficial.

But there will be differences in risk for particular moods and psychological symptoms.  There's an Asian psychiatrist in Los Angeles who has written several papers that, for example, Asian patients in Los Angeles require half the dose of Prozac or Valium than Caucasian patients with exactly the same psychiatric diagnosis.

So we return to voles again.  This research has just begun.  I must confess to you as I now stop that I'm surprised by these results.  I wouldn't have expected them.

When I was a graduate student, I was very hostile to the role of biology in human affairs.  I was convinced that most of the variation among 20 year olds was a function of what happened within the walls of their family, but I've been dragged to this conclusion by their data, even though as I've shown you the role of the environment is powerful for temperament constrains rather than determines.

Thank you very much.

(Applause.)

CHAIRMAN KASS:  Let's agree to have just a couple of minutes for questions of clarification, although the two papers I think might be best discussed at the end.

Diana Schaub, Diana.

DR. SCHAUB:  You spoke of ethnic and racial differences.  Are there sexual differences also?  Do girls tend to be more high reactive than boys?

PROFESSOR KAGAN:  Right.  Surprisingly, there's no difference at four months.  High reactive and low reactive infants, it's equal on the sexes.

Now there's an interesting story.  Under age seven or eight more high reactive girls are timid, shy, introverted than boys.  But by adolescence, it has changed.  Now, I think this may be—here's my hypothesis.

At 15, it's just the opposite, and I think it's because girls in this culture are gentler with timid girls than boys are.  Boys are very cruel, and so at 15, which is the age we're studying now, high reactive boys who have not lost their persona, they are very shy, very frightened, very introverted.

Our girls are garrulous, have many friends, and my own belief is that that's all environmental.  It's because girls are less cruel toward a girl who is initially timid in her personality.

But there is no difference at four months.

CHAIRMAN KASS:  Jim Wilson.

PROFESSOR WILSON:  Thank you very much, Jerry.

You said toward the end of your remarks, speaking, I think, of adult populations, that psychiatrists should gather biological evidence.  What kind of biological evidence, and how do they gather it?

PROFESSOR KAGAN:  I would say I think it would be very useful if as part of the psychiatric  examination, I'm thinking of something that could be done in the office.  You could easily gather sympathetic and vagal tone, easily.  Given the fact that many are associated with the hospital, you could order an EEG and get right and left hemisphere dominance, yeah, and I think that would help the diagnosis.

CHAIRMAN KASS:  Other questions?  Michael Sandel.

PROFESSOR SANDEL:  This is a simple minded question, Jerry, but what was the question that drew you to this?  Were you trying to figure out what makes some kids shy and some kids bold?

PROFESSOR KAGAN:  No.

PROFESSOR SANDEL:  What was the animating question for you?

PROFESSOR KAGAN:  The animating question was this.  My first job was at the Fels Research Institute in Yellow Springs, Ohio, in the campus of Antioch College.  I inherited a corpus of data that has been gathered since 1929, and Howard Moss and I studied the adults, and he rated the children, and only one trait was stable from the first two years of life to adulthood, and it was these two traits, but I didn't understand it in 1957.

But I was thinking about it, but I resisted.  Then Zowazo, Richard Kiersley, and I were doing a study of the effect of day care.  Remember years ago, in 1978, the Congress was going to vote day care, and we were certain day care was bad for infants.  So we got an NIH grant, and we began to study in the South End the role of day care on young infants.

But we needed political protection.  Things were very bad then if you remember, and so the Chinese Christian Church said, "We'll protect you, but you must take Chinese American infants from Boston's Chinatown." 

So we had half Chinese American infants and there it was, and that's when I saw that these children were temperamentally so different.  Then I remembered the Fels, and of course, I had been studying children for 40 years, and I realized I was resisting the notion of temperament.  I was resisting it.

And my resistance collapsed, and that's why I did this.

CHAIRMAN KASS:  Peter Lawler.

DR. LAWLER:  You seem to have, as far as I can understand, covered some of the wisdom of Machiavelli, right?  Some people are impetuous; some people are cautious.  These are natural things.  We really can't change them very readily, and which is better sort of depends upon circumstances, and the point of education is to rein in the destructive aspects of one or the other.

But then the last page of the very fine chapter that you gave us you said what we now have to do through education we will eventually be able to do through pills.  Do you really think this is so?

PROFESSOR KAGAN:  Oh, no.  I'm sorry.  I hope you didn't misinterpret the last page.  This book says in our technological culture both types have advantages.  There's a line, I think, in the chapter which says if we ask T.S. Eliot the day after he won the Nobel prize, you know, you—if you read his biography, he was a very inhibited child—you know, would you have wanted your mother to give you medicine, he would have said no, because he wouldn't have become a playwright.

We need people who like to work alone, bench scientists, programmers, and of course, that's where our high reactives drift, and we need statesmen and surgeons and trial lawyers, and I think the account is balanced.

If I can tell an anecdote that Steve Suomi told me, on the island of Cayo Santiago, which lies off Puerto Rico, there are 1,000 Rhesus monkeys.  No one lives there, but graduate students code their behaviors.  They know which ones are timid, which bold.

And one spring, Steve—

PARTICIPANT:  (Speaking from an unmiked location.)

PROFESSOR KAGAN:  Sorry?  No, the monkeys.  Sorry.

In one year two juvenile males died of starvation.  They were the timid ones.  Because food is put out once a year, and they wait, and if you wait too long, you die of starvation.

Two bold monkeys died because they attacked two large alpha males, and so four males died, two from one temperament, two from another, and the account is balanced.

We don't tell our mothers of high reactors that, you know, this is a trait you should change.  In an earlier study, one of our most inhibited boys said to an examiner at nine or ten, to the question what do you want to be, he said, "I want to be a scientist, physicist."

"Why?"

He paused, and he said, "I like being alone."  That boy is getting a Ph.D. in physics from Berkeley this year.  He's going to be a productive member of our society.

So in a society as diverse as ours, it is not obvious that one of these temperamental types has advantages and you wish to change it.

DR. LAWLER:  So although you try to be nonjudgmental here at the end, you actually are quite judgmental on this.  That is, nature has given us a pretty good deal.  We shouldn't mess with it that much.

PROFESSOR KAGAN:  Yeah, I think in our society, which is mobile and youth leave their homes and so many jobs require dealing with strangers and risks with minimal uncertainty, at this historical moment, not in colonial times, there probably is a slight advantage to the low reactive, slight, yeah.

CHAIRMAN KASS:  Let's just take one more, and then we can hold the rest of the conversation.  Gil, do you want something short?

PROFESSOR MEILAENDER:  I think so.

You used the words "bold" and "timid" with respect to temperament.  Moralists in speaking about virtues sometimes use words like "courageous" and "cowardly."  What would be the relationship do you think between your words "bold" and "timid" and the moralists talk about "courage" and "cowardice"?

PROFESSOR KAGAN:  I'm glad you asked that.  Very different.  When I use the word "bold" and "timid," I mean what is your initial reaction to a challenge or a novel event.  Is the initial tendency to psychologically freeze, encase it, or go forward?

That has got nothing to do with defending your values, and as a matter of fact, the interviews at age 15 are revealing that it's the high reactives who are more likely to defend their beliefs.

Let me end by reminding you of that wonderful paragraph in Portrait of an Artist.  Remember Stephen Daedalus is Joyce, who is a frightened, timid boy, and remember his mother.  He's talking to a friend, and he says, "I'm not going to Easter mass.  I don't believe in it."

He says, "But your mother wants you to go."

And then he says, "No, I shall be a hypocrite."

He says, "So what?  You don't believe.  Go to please your mother."

And Stephen says, "I can't."

That's often the reaction, so that in terms of courageously defending your beliefs, I have the inkling—and I'll stop—that those are the high reactives.  They're often ideologically more courageous.

CHAIRMAN KASS:  Let's hold the rest of the discussion until we have Dr. Spelke's presentation.

PROFESSOR SPELKE:  While we're waiting for the PowerPoint to come up, can I just ask if anyone has a laser?  That would be great.  If not, I'll make do.

CHAIRMAN KASS:  Do we have one or not?

PROFESSOR SPELKE:  If not, it's okay.  I can do without.

Thank you for inviting me today,  My task is both exciting and impossible.  There's no way that in 40 minutes I'm going to really be able to convey to you what we've been able to learn about children's cognitive development, but I do want to try to talk about three aspects of the work that has been going on.

First, I want to tell you a little bit about the methods that have been developed over the last 50 years or so for addressing questions that people have asked for 2,000-plus years about the origins of our understanding of the world, the experiences of young infants, the states of knowledge of infants and how our knowledge grows and changes with development.

These questions are very old, but research strategies for addressing them have really emerged in the last 50 years, and I want to introduce you, in particular, to two research strategies that have been important and will do so in talking about space perception.

Then I want to turn to some substantive topics and talk about two core systems of knowledge that I think these strategies have given us evidence for in young infants.  One is a system for representing and reasoning about the physical world, particularly solid, manipulable objects, and the other a system for representing and reasoning about people.

And then my final substantive topic, I want to turn from the systems of knowledge that infants have to some central systems of knowledge that they appear to lack and that children appear to construct over the course of the preschool years from about age two to about five.

And although there's many such interesting systems, because of time limits I'll just give you one example and talk about the construction of natural number concepts, and then if there's time at the end and you'll permit me, I wanted to lay out just a couple of themes that I thought might suggest questions that you would want to consider in this group.

So beginning then with the origins of space perception, as I said, this is a very old question, but until relatively recently, "recently" being around the mid-1950s or so, there weren't systematic attempts to answer it because there seemed to be this insurmountable obstacle.  In order to answer these questions, we needed to understand what human infants experience about the world.

Yet human infants have extremely limited abilities to act on the world, to communicate with other people, to convey to us what their experience is.  And that seemed to place a major obstacle in the path of pursuing this research.

Well, I think the first serious progress in overcoming this obstacle came about around the end of the 1950s through the work of Eleanor J. Gibson and her collaborators, and the crucial research strategy that she employed was a comparative strategy.

She started with incidental observations on newborn goats, that if you took a goat just born and put it on a flat surface, it would start walking around, but if instead you put it on a tiny stool, it wouldn't move.  It would freeze and not move off the stool, and Gibson wondered what role visual information might be playing for the goat in controlling this behavior. 

So she designed the now-famous visual cliff.  This is a simple apparatus where there's a center board that you put an animal on, and two plexiglass surfaces immediately below the center board.  So immediately below the center board on both sides are two surfaces that will support the animal, which if the animal reaches out and touches them, they'll feel that they're rigid surfaces of support.

However, on one side, she put—if I had a pointer, I would point to the right there—she put a visual pattern directly below the plexiglass.  So the surface not only was solid.  It also looked solid.

Whereas on the other side, she put that pattern much further away.  So it looked as if there was no surface of support there, even though there was one, and what she found was that newborn goats placed on the center board would readily go scampering off on the visually shallow side and avoid the visually deep side.

Now, of course, this is useful to goats, since they live on mountains and need not to fall off them, but this observation raised the question, is this an ability that we'll only see in animals living in those kinds of environments or will we see them more generally? 

And to address that, Gibson repeated the visual cliff experiments on a wide range of different animals, including rats and kittens and human infants.

The findings are easy to summarize.  For any terrestrial animal that she studied, at the point at which the animal becomes capable of locomoting on its own, which is at birth for some animals; it's after a few weeks or months of birth for other animals; for human infants, it's about six to eight months after birth.  At whatever point an animal begins locomoting on its own, they would locomote over the visually shallow side and avoid the deep side.

The next question Gibson asked then was:  is each of these abilities in different animals due to a distinct mechanism or, rather, is there a single general mechanism for perceiving depth and using depth to guide locomotion that evolved in some distant ancestor common to all of these animals and, therefore, the same mechanism at work across animals?

To address that question, Gibson did a whole further series of studies, which I don't have time to describe, looking for each animal at the signature limits for cliff avoidance.  That is to say, the conditions under which they would succeed in avoiding a visual cliff and the conditions under which they would fail, in which she found across this range of animals was common limits across the animals, providing evidence that common mechanisms were at work in all of these animals.

Finally, a question arises.  What about for those animals that don't locomote at birth and that require some weeks or months of postnatal experience before they start engaging in visually-guided locomotion?  What role does experience play for those animals?

Well, this is a question that one can't ethically ask for human infants, but one can ask for other animals by doing controlled rearing experiments, and Gibson did a whole series of experiments where she reared rats or kittens in darkness or with nonspecific visual stimulation or with specific experience with cliffs.

And to make a long story short, what she found was that in those animals this ability developed independent of any specific learning about the effects of cliffs.  In some animals nonspecific visual stimulation was necessary for the development, probably for the reasons that Dr. Jessell talked about earlier today, but no animal needed to learn to avoid the drop-off.

So the conclusion from all of these studies is that depth perception is innate in the sense that it develops independently of specific learning in mammals, including humans, given the evidence that common mechanisms are at work across these animals.

Nevertheless, there's two general related limitations to this line of work.  It doesn't allow—when you study systematic, coordinated behaviors that only emerge late in human infancy, you don't have the possibility of studying the actual development in humans of these abilities until those behaviors emerge.

And the second limitation, this comparative method works great for studying the development of abilities that we share with other animals.  It's less clearly applicable to studying developments that are uniquely human.

So let me introduce the second research strategy that has been important for this field.  There are a number of people responsible for it, but I think one watershed set of studies were provided by the psychologist Robert Fantz, again, in the late '50s.  He focused on the fact that human infants from the moment of birth do engage in at least one highly systematic and controlled behavior.  They look around the world, and they will show systematic tendencies to look at some things more than others.

So drawing on this observation, Fantz developed the preferential looking method, which you see a picture of here.  What you have is a baby lying on its back.  It's looking at two visual displays side by side, and between the displays is a peep hole.  Back in the '50s you didn't have a video camera, I guess, to do this, and a person looking through the peep hole and just judging which of the two displays infants looked at.

And he found that down to newborns infants would show systematic visual preferences under certain conditions, and two particularly interesting ones.  First, they would tend to look longer at novel arrays.  So if you presented an infant over a whole series of trials with, say, two red circles on both sides of the peep hole, and then after they had seen those for a while you presented one red circle and one green square, the infants would tend to look longer at the new display, showing that they were showing some form of memory and visual discrimination, and I'll come back to that novelty preference later.  It's not incompatible with the novelty weariness when you present an entirely new situation that babies show under other conditions.

The second finding was that infants looked longer at three dimensional displays than at two dimensional displays, and that's actually the study that's being pictured here.  What a baby is being shown is a sphere, three dimensional sphere on one side of the peep hole and a flat disk on the other side, and the babies looked reliably longer at the sphere.

Now, this may seem to show that babies perceive depth, but actually it doesn't because there's two different accounts one could give of that visual preference, as the psychologist Richard Held pointed out some 20 years later.

One way to illustrate these two different accounts is to consider some experiments that Held did himself.  Now, these experiments were looking, testing for the development of a certain kind of depth perception, not the only kind, but the one whose neural mechanisms Professor Jessell was talking about this morning, perception of depth from stereopsis.

And for these studies, Held put stereoscopic goggles on infants such that each of the two eyes was seeing a different display, different pair of visual displays.

One of the displays that was projected to both eyes projected exactly the same array to both eyes, and for an adult with normal stereoscopic depth perception, that looks like an array of flat stripes.

The other display presented stripes that were two patterns that were slightly offset with respect to each other, to the two eyes, and when you put on stereoscopic goggles and look at that display, you will see stripes arrayed in depth.

Now, the first thing that Held found was that at about four months of age, between three and four months of age, infants start looking longer at the display that we adults see as stripes arranged in depth than at the display that we see as flat.

But Held pointed out there's two very different stories you could tell here about this preference.  On the one hand, maybe infants are also seeing depth just like we do.

On the other hand, it's possible that when infants look at the display on the right, they just see a pair of double images, whereas when they look at the display on the left, they see a pair of coincident imagines that fuse into a single imagine, and so a very different experience could be underlying their preferential looking relative to our depth perception.  So how do you get around that problem?

Well, what Held suggested, and this is the critical research strategy that I think has been followed in most of the work that has been done since this time looking at perceptual and cognitive development, what he suggested relies on 100 years of work on the type of physics of depth perception in adults, work that reveals that we adults perceive depth from stereoscopic information only under a very restricted and well defined set of conditions.

So, for example, in a display like this, we'll see depth if the edges are slightly offset from each other, but not if they're very far offset from each other.  We'll perceive depth if the edges are vertical, but not if they're horizontal.  We'll perceive depth if we look through the stereogram with the glasses on, but not if we take the glasses of.

And so Held suggested we can look across this range of conditions at when infants do and don't show the preference for the display on the right.

And what he found was that infants' preferences lined up down the line with adults' perception of depth.  Infants preferred the display on the right, starting at about four months under all and only the conditions in which adults perceived depth.  So that common set of signature limits suggests that infants aren't just responding to double images.  Rather, they've got the same mechanism that we have and it's working in the same way, giving us reason to attribute to infants the same kind of experience of a three-dimensional world at that point in development as we have as adults.

So to conclude this first section, what this work put together suggests is an answer to a 2000 plus year long debate.  The tendency to look out into the world and see a stable array of surfaces at a distance from ourselves and stable, coherent three-dimensional arrangements appears to develop largely independently of experience.  We seem to be built to perceive space.

The mechanisms by which we do so are not unique to humans.  They're shared with other animals.  And the mechanisms by which we do so as adults have a long developmental history in us.  We see the same mechanisms at work in human infants.  And these continuities, ontogenetic and phylogenetic, provide  a set of tools that we can use for shedding light on infant's perception capacities and also on some of their cognitive capacities.

So what I want to do now is use these tools and take you very briefly through some of the highlight conclusions of research looking at what infants understand about inanimate objects and what they understand about people.

I'll be particularly fast in talking about objects because this work is relatively older and some of it was in some of the supporting materials that there circulated to all of you, but basically starting as using Gibson's approach focusing on adaptive behaviors on objects and particular in these studies the adaptive behavior would be reaching out for objects and manipulating them and also studies using Fantz's approach focusing on preferential looking and in particular the tendency to look longer at novel events.  These two lines of studies have both been conducted to ask, what do infants see when you present them with an array of objects.  And they converge on the same set of conclusions.

One conclusion is that infants have capacities that we also have as adults, starting as young as about 2 months of age, maybe younger, though.  It's hard to do these studies when infants are younger.  Capacity is to take a continuous array of surfaces and break it into units.  And the boundary of those units generally coincide with the boundaries that we take to be the objects, in a scene.

So, for example, if you present a baby with two objects sitting on top of one another, one of which slides over the other but remains in contact with it throughout that motion, present it until babies are bored with it, and then reach out and lift up the top object and either it moves by itself or the two objects move together, babies look longer if the two move together, suggesting that even though the objects were in contact throughout the time the babies were becoming bored with them, they were nevertheless perceiving a boundary between them.

Other studies have asked whether babies are able to interpolate parts of objects that are hidden from view.  If you see an object whose top and bottom are visible and its center is hidden behind another object, can babies ever extrapolate that connection between the two and see a connected object?  And again  the answer is they can, if you bore them with a display like this, a rod moving together behind a block, never enough for its center to come into view.  They will be relatively bored if you then take the block away and show them a complete rod, suggesting that that's not new to them, that's what they were seeing before and relatively more interested if you show them a rod with a gap in the center.

Further studies have asked whether babies are able to represent objects as continuing to exist when they move fully out of view.  And these studies show that they can, under certain conditions, and that they keep track of objects that move in and out of view in accord with the basic principle that objects are going to move on spaciotempororally connected paths.  They're not going to jump from one place in time to another.

So, for example, the study of ours took four months old infants looked just at the—I'll just describe the case on the right.  Four-month-old infants and presented within an array where there's two screens, an object moves behind one screen.  Then there's a pause.  And an object that looks just like it moves out into view from behind the other screen.

Now, adults looking at that will infer that there's two objects in that event behind the screen because one thing couldn't move from far on the left to far on the right without traversing the space between the two.

To see if babies perceive that, we again bore them with the event I just described and then remove the screens and alternately show them arrays with one versus two objects.  They look longer when you show only one, suggesting that they like us, perceived two objects in that scene.

And one last example, studies have asked whether babies are able to make inferences about mechanical relationships between objects.  And in particular, if babies infer that objects will act on each other when and only when they come into contact.  This is one of the earliest experiments that was done by, I think, an undergraduate at the time.  It may have been an undergraduate of Jerry's, William Ball.

Here's the events that he presented to infants.  There's a screen.  There's an object that's partly hidden behind the screen and another object that moves behind the screen, and when it's fully out of view, the object that's initially half hidden and stationary starts to move, okay.  Now adults look at that and infer that the first object hit the second and set it into motion.  But actually, the event is physically consistent both with that possibility and with the second.  The screen is big enough that the first object could have stopped short of the second object, and it could have started moving on its own.

So to see whether babies made the same inference as adults, we bored with the top event, and when took the screen away and then indeed they looked longer at the event where the first object stopped short of the second, suggesting that they inferred that the two would come into contact.

Well, putting all this work and other related work together, I proposed and others have proposed that babies starting at about two to four months have a system for building representations of objects that accord with three general spaciotemporal constraints on object motion.

They build objects that are cohesive, that is, bodies that are internally connected and move relative to one another, that are spaciotemporally continuous, that is, that these are things that bodies can't do.  They move on connected paths, but they don't jump from one place to another and their paths also don't intersect, such that two things occupy the same space at the same time.  And they move when and only when they come into contact, there's no action at a distance.

But interestingly, this is not to say that infants perceive objects under all the conditions that adults do.  My colleague Susan Carey has discovered some interesting limits to infants' abilities to perceive objects.  If you present them with situations where spaciotemporal information for properties like cohesiveness and continuity do not dictate where the boundaries of objects are.  For example, you place a toy duck on top of a toy cup, presenting no relative motion between the two, no motion at all in the scene, infants' perception of the boundary of those objects is indeterminate.

Now recently there's been a lot of beautiful work, some of it on the island of Cayo Santiago that Jerry was talking about asking whether this same system of representation exists in nonhuman primates and also asking whether the same system exists in adults.  And like the strategies of Gibson and Held, the way of asking whether the same system exists is to ask do we see the same abilities and the same limits.  Well, to just simply give you the answer, since I don't have time to take you through the studies, the answer appears to be yes in both cases.  This system exists in adult rhesus monkeys.  It also exists in human adults when you test us under conditions where we're not able to use our specific knowledge about the world, our language, other strategies that infants lack to track things through time.  We show the same patterns of success and failure as infants do.

Well, let me turn to the other core system that I wanted to lay out for you.  This, I think, is a system for reasoning about persons, and there have been many signs from studies of infants over the last 20 years or so that the system exists and is at least as important for infants as the system for representing objects. 

One source of evidence for this system comes from some studies conducted by the psychologist John Morton and Mark Johnson with newborn infants.  They took brand new babies, put them on the lap of an experimenter, and presented them with simple schematic oval-shaped patterns, either a pattern representing a face or one of a number of other kinds of displays.  And when the baby was looking at the pattern, they slowly moved it to the left or right, and the measure was how far would the baby follow the pattern, how far could they move it before the baby would lose interest, turn away, no longer track it?  And what they found was that babies would track for the face pattern at birth reliably longer than for the patterns that clearly were not face-like and not reliably, but somewhat longer when they tracked a simplified face pattern as well.  And this study and others suggests initial sensitivity to the structure of the human face.

Here's another ability that comes in by about two to three months of age from studies by Bruce Hood.  In these studies, infants view the face of a person on a computer screen looking straight at them and then, I don't know if you can see it up here, but the person's eyes turn either to the left or to the right, and right after that the person disappears and an object appears either on the left or on the right.  Now no matter which side the object appears on, the babies turn to look at it.  But when Hood measured how fast babies turned to look at it, it turned out that they turned to look to the object faster if the person's eyes had—if it appeared on the same side where the person's eyes had turned than if it had appeared on the opposite side.

So from about two to three months of age, babies are sensitive to human gaze, and they're following the gaze of a person who's looking straight at them to an object that's facilitating their attention to other objects.

Well, what about people's actions?  Do babies form any sensible representations of other people's actions?  Well, this is something that psychologist Amanda Woodward has been studying for the last five years or so through some simple ingenious preferential looking experiments.  In these experiments, she shows a baby two objects and a person whose hand reaches repeatedly for one of the two objects, so for example, for a given baby it might be the ball.  After the baby has gotten bored with looking at this, she then switches the positions of the two objects and has the hand alternately reach to one versus the other. 

Here's the reason for doing the experiment.  The question is, when the baby sees the person reach for an object how do they encode what the person is doing?  Do they think the person is just like an inanimate object that would move from one position in space to another position in space or do they encode the action as goal-directed, directed to the goal, in this case reaching for the ball?  Well, if they encoded the action as simply a movement through space, then this should be the event that's most similar to it.  But if they encoded it as an action directed at a goal, then when the two objects move, it's the new action to the new position to the old goal that should be seen as more similar, and infants' looking time was consistent with that second possibility.  Okay?  Infants looked longer when the goal changed than when the physical trajectory of the action changed.

PROFESSOR SANDEL:  Could I just ask you, the test, though, is looking longer?

PROFESSOR SPELKE:  Right.

PROFESSOR SANDEL:  How do you know what that means?  How do you know whether they're looking longer because they're making sense of it or they're looking longer because it doesn't make sense?

PROFESSOR SPELKE:  Okay, in all of these studies, the pattern of data internal to the study answers that question, okay?  So for example, you can have conditions in which you don't change the positions of the objects.  Right, and so if they're looking longer to something that's familiar or sensible, they look longer to the old motion than to the new, but that's not what they do.  Does that make sense?

So I mean this is a situation that pits two kinds of novelty against each other and when we see they look longer to this, we're assuming they're going to look longer to novelty. 

PROFESSOR SANDEL:  That's my question.  Why do you assume that looking longer corresponds to novel—the perception of novelty?

PROFESSOR SPELKE:  Right, because you can also do studies where instead of pitting two kinds of novelty against each other, you can pit an event which by any description is more novel against an event which by any description is more familiar.  So suppose, for example, instead of switching the positions of these two objects, we just left them where they were, let the babies get bored with one and then alternately show reaching to the old one versus reaching to the new.  Infants will look longer at the new one, and so that's suggesting that in this situation when they're bored, they will tend to prefer the more novel event.  Did that make sense?

PROFESSOR SANDEL:  I thought the question—

PROFESSOR SPELKE:  Let me—

PROFESSOR SANDEL:  Please, so ahead.

PROFESSOR SPELKE:  Let me keep going because I think in principle that is a real concern and in practice the pattern of results across the studies addresses it.

The one last thing I want to tell you about the Woodward studies is that this effect is specific to people.  When she's repeated these experiments with inanimate objects moving towards—and the inanimate object she used was superficially in some ways similar to a human hand and arm.  It was a stick with a sponge like deformable thing on the end of it and she bores babies with the stick moving to the ball and then switches the positions of the two objects.  She does not get a preference for moving to the same goal, suggesting that this propensity to understand actions as goal-directed is applied to people in infants of this age and I should have said these are five-month old infants.  It's not applied to inanimate objects.

Finally, there are other studies, infant sensitivity to human actions, that show that babies are sensitive to relationships between what they themselves do and what other people do.  The most famous studies, also were very controversial for a long time, were conducted by Andy Meltzoff some 25 years ago and showed that when, for example, he sticks out his tongue at an infant, infants will reliably not really stick out their tongue in kind, but act in a way that a blind observer looking at it would judge to be more like sticking out your tongue than like other events that the model engaged in.

We now know after many years of controversy that this ability in newborn infants is extremely limited, but it is real and it leads to much more dramatic abilities to attend to the actions of other people and reproduce their actions on objects later in infancy.

I have just one example here to share with you.  This is also from a study that Meltzoff conducted with much older infants.  Starting at about nine months of age, if an infant views a person acting in a particular way on an object and then that object is presented to the infant, the infant will tend, if possible, to reproduce the action that they saw the person perform.  In this study, which is with infants that are somewhat older, they're about 14 months.  Meltzoff went a step further and asked what will happen if an infant sees a person attempting to do something but failing, and in this study the person is attempting to take this little barbell and pull it apart and failing to pull it apart.  What he found was that when he then gives the barbell to the infants they grab it and pull it apart.  And again, this is specific to people when they see the very same series of motions, but it's a machine that's doing the actions, they don't show that effect.

Okay, so these are all ways in which infants seem to be able to make sense of the actions of other people.  But we can ask, do infants also apply their understanding of inanimate objects to other people?  Do they expect that people will interact on contact, that people will exist and move continuously.  And some experiments have begun to ask this.  In particular, Woodward did a series of studies where she took up the old experiment by Bill Ball showing that babies infer that two inanimate objects that move in succession come into contact and asked, will they make the same inference for people?  So for this study she presented infants with videotaped events of real people or real large complicated inanimate objects, things like potted plants and high chairs, not the objects that I've diagrammed there, conducting the same experiment that I described earlier.

What she found is that as in the previous experiments, when the objects were inanimate, infants inferred that when two objects moved in succession, they came into contact, but when the objects were people, they did not.  Okay?  No inference that the first person slammed into the second to set them into motion.

Finally, very recent set of studies being conducted at Yale in the lab of Paul Bloom have asked whether infants infer that people's motion is subject to continuity.  And here they took our method for studying continuity that I already described to you, two screens and an object that moves behind one and then another object that appears behind the other and they found, like us, that when the objects are inanimate infants infer that if there's been discontinuous motion there must have been two objects.  Interestingly though, they don't infer that in the case of people, even though it's true, right?  A person can't move from the first place to the second without passing through the space in between, but infants don't infer that people's behavior is subject to that constraint.

So to summarize what I've told you about infants' understanding of inanimate object motion and human action, I think we see evidence here for two quite distinct systems of knowledge.  In the case of inanimate objects, infants reason about object motion in accord with a principle of no action at a distance, contact mechanics, if you will.  They infer that such objects are not goal-directed.  They don't show goal-directed inferences in the Woodward kinds of studies.

In the case of people, you see just the reverse.  People are predicted to act in relation to goals and not in relation to proximal mechanical forces. 

Similarly, tracing people over time may involve making inferences about their intentionality.  Certainly babies seem to be sensitive to intentionality, and it doesn't involve making inferences about continuity, whereas for inanimate objects the reverse would seem to be the case. 

So it looks like we have two distinct systems here.  Now I've raised the question that I can't, unfortunately, answer about whether these systems show continuity over phylogeny and also over ontogeny.  In the case of studies of nonhuman primates, there are a number of studies now of nonhuman primates showing that pieces of the abilities that we see in infants are shared by other animals, but there's currently a debate in the field as to whether the entire set of abilities that we see in human infants are part of our primate heritage of whether any of them are unique to us.  I think that's a question we have to leave on the table for the moment.  The decisive studies on nonhuman primates just haven't been done.

In the case of ontogeny, I want to throw out a speculation to you.  This is an interesting group, I think, in which to do this because I believe you may have already heard presentations from some neuroscientists saying there's really only one system of causal relationships that underlies all behavior.  Human beings are just complicated machines.  Our minds and brains operate in accord with the same mechanical principles as inanimate objects.  And if one takes these claims seriously, it would seem to suggest that people can come to overcome this notion that people and inanimate objects are fundamentally different from one another.

My own experience though, for what it's worth, is that colleagues who say these things to me about human action tend to agonize over personal decisions as much as anybody else does, tend to experience moral indignation.  I think that this notion that people choose their actions and could have acted otherwise is actually very deeply ingrained within us, and I think we're seeing the origins of it in these studies with infants.

Okay, I want to completely shift for the remainder of my time and talk about some capacities that we don't see in other animals for sure and that we also don't see in human infants but that we do see in most children at the time that formal education begins, a set of distinctively human concepts and abilities—one of the abilities which I didn't put up here is the capacity for language—that allow us to communicate with one another, to use symbols and to use abstract concepts that are at the basis of all science and technology and much of modern life.

Now, what I want to suggest in the case of all of these concepts is first of all that infants lack them; second of all, that these concepts aren't explicitly taught to anyone.  They develop spontaneously in children, most children between the ages of about 2 and 5; third, that their development depends, in part, on experience; and fourth, that their development is absolutely necessary for formal education, that a child who hasn't developed these fundamental concepts will be at serious disadvantage in formal educational setting.

Now if I had hours and hours I would try to tell you about all of these.  Since time is very limited, I want to try to flesh out these claims by looking just at one set of concepts, natural number concepts.  And what I will try to do in my last few minutes here is begin by telling you very quickly about two core systems for capturing numerical information that we do find in infants and nonhuman primates, as well as in us adults, one for dealing with small numbers, the other for dealing with large approximate numerocities.

Then I want to talk about the construction of the uniquely human natural number concepts over the course of the preschool years and then finally, I want to give you a bit of evidence that this construction depends, in part, on experience.  So the first core knowledge system that serves as a building block for children's number concepts I've already introduced you to in talking about objects.  This is a system for representing small numbers of objects and all I want to point out here is that it has some of the properties of our system of natural number.  So this is a system, for example, that research by Karen Wynn has shown babies are able to use to do something like compute the effects of adding an object to a scene or taking an object away from a scene.  If you place an object on the stage, this is again a preferential looking experiment, 5-month-old infants; place an object on a stage, cover it by a screen, add a second object to the scene and then ask infants, in effect, how many objects are there by lowering the screen and presenting either the right or wrong number of objects.  Infants will look longer if you present the wrong number, and they do that both in this one plus one kind of problem and also in other similar problems.

Infants can also use representations of small numbers of objects to make numerical comparisons, and these are studies that have been explored most thoroughly with older infants about 12-month-olds.  Research in Susan Carey's lab has taken 12-month-old infants and presented them with graham crackers, putting one plus one equals two graham crackers into one box.  Two minus one equals one graham cracker into the other box, pushing the boxes apart and encouraging the infants to crawl to them.  And infants will tend to crawl to the box that has the larger number of graham crackers, showing that it can both represent the numbers in each box and compare those numbers.

But as always with infant research, the limits to infants' abilities are as interesting as the abilities themselves and in particular, in these situations we see two general limits.  The first is a domain limit.  You see these abilities when you present babies with solid, manipulable objects.  You don't see them when you present them with nonsolid substances or many other kinds of perceptible entities and the second is a set size limit.  You see these abilities when you present up to three objects, but when you present more than three objects babies fall apart.

So here is the results, for example, of the box choice study, one versus two graham crackers, they go to two.  Two versus three, they go to three.  But if you then test with three versus four or even four versus eight, they're choosing at chance between the two.  They're not able to keep track of more than about three objects.

Now we see the same limits in monkeys.  This is research by Mark Hauser and the same limits in human adults when you prevent us from counting or otherwise verbally encoding the displays, suggesting this is the system that shows considerable continuity.

The second system has been revealed through experiments using an even simpler novelty preference method.  For example, a method that's been used a lot in studies of speech perception where you take an infant and present them with the sequence of sounds coming out of one of two side speakers, simply measure how interested they are in the sound sequence by seeing how long they will turn their head in the direction of the speaker.  Then you can test for their abilities to discriminate different numbers by familiarizing infants to a set of different sequences all presenting the same number and then testing them with new sequences alternately presenting the same number of a different number.  I hope this is clear.

So what's illustrated here, half the babies are bored with four sound sequences, with four sounds; half with sequences of eight and then everybody is tested with sequences of four and eight, and you see will they turn their head to the speaker longer when they hear a new number?

And very quickly, the findings, the study has been done with many different numerical discriminations.  The findings are at about six months of age, the first age at which you can use this method, babies do show abilities to discriminate on the basis of number.  They'll discriminate sequences of four from sequences of eight, for example.  Their number discriminations are imprecise.  So if you repeat the experiment to test discrimination of four from six, they fail.  And what determines whether they succeed or fail is the ratio of the two numerocities.  So a baby who succeeds with 4 versus 8 will succeed with eight versus 16.  If they fail with 4 versus 6, they'll fail with 8 versus 12.

And finally, as you test older babies, you find that the critical ratio for discrimination narrows.  A 9-month old in particular, will succeed with a two to three ratio that the 6-month-old fails with.

Now one can vary the kinds of events or displays presented to infants to see whether this is an abstract system of number representation by instead of presenting sequences of sounds you can present sequences of actions, a puppet that jumps some number of times.  You can also present visual spatial arrays, arrays of dots, of one or another numerocity.  The findings from those studies line up perfectly with the findings from the studies with sound sequences.  If babies can discriminate a given pair of numbers of sounds, they can also discriminate that pair of numbers of dots or visible actions.

Now these large number representations show two signature limits.  One that I've already described is the ratio limit on discrimination.  The other limit I also described earlier in talking about the first system.  It's a tracking limit.  Babies are able to discriminate 8 events from 16 events when the events occur in immediate succession in an object that's continuously visible.  But if they see one at a time, four objects going into a box versus eight objects going into a box one at a time, and they have to track each of these individuals as it's hidden, they are not able to use this large number system in that case.  So the same limits have been found in monkeys and also in human adults, people like us, when we're prevented from counting or otherwise use language to encode the displays, suggesting that the second system is also showing continuity.

So it looks like we have evidence for two systems capturing aspects of numerical information in infants, one focused on small numbers, the other focused on large numbers, each system showing successes and failures under a distinctive pattern of conditions.

So the question then is what happens to these two systems, as children learn verbal counting, as they interact with other people, and as they develop the kinds of number systems that they're going to need to use in school? 

Now clearly, when children go to school, the assumption is made that they've got one system of number concepts, not two; that the system shows neither a set size limit nor a ratio limit.  Natural number concepts allow you to represent whole numbers precisely with no clear upper bound.  And that each number concept refers to a set of numerically distinct individuals.  And the question is where did these representations come from?

Well, I think some very interesting work that began again with Karen Wynn and has been pursued by a number of different investigators since then suggests that these number concepts actually emerge well after children first learn the verbal counting routine.

So in most American households, somewhere around age 2 or two and a half, children start engaging in counting.  I'm sorry this is so distorted.  There are supposed to be about nine fish on this table, and if you take an average two year old and say how many fish are here, the child will very likely go through the routine of pointing at each of the fish one at a time and going one, two, three, four, five, etcetera, engaging in verbal counting.

What Wynn showed, though, is that at this early point when children are engaging in this activity, they don't have the faintest idea what these words mean or what the activity is about.  And one way to show that is to ask them a simple question.  After this child has counted all nine fish—here's a pair of questions that shows this.  After the child has counted nine fish, you ask the child would you put one fish in the pond?  And the child succeeds.  That shows the child understood the question, is motivated to answer correctly.

So now you ask would you put two fish in the pond?  And I can tell you the reaction of my son, aged two years or so at the time that Karen conducted this experiment on—she was conducting it at the time, and she came to visit us and did it on him.  He looked at her as if she had suddenly switched to a foreign language.  He didn't have the faintest idea what she wanted, and he then grabbed a handful of fish and put them in the pond.  What her data showed was that at this point there was no relation between the number asked for and the number given, except that a child always gave one when asked for one and always gave more than one when asked for another number.

Now this state persists for about nine months.  For about nine months children are using all of these number words in the verbal counting routine without understanding what any of them mean.  And then somewhere around age three and a quarter or so, children learn the meaning of the word two and at that point when you ask for two, you get two.  When you ask for three, you'll get a handful, but not one and not two.  And about another three months later, they learn what the word three means, and then something magical happens, and they figure out what the whole counting routine is about.

Now what could be going on here?  I think in light of the work on infants, we can make the following suggestion, that in the initial step of learning verbal counting, children figure out that the word one applies when you've got a single object, a single individual to represent, and the system for representing small numbers of individuals may support that induction.

They also know that the other number words apply when you've got a set, a bunch of things, some nonspecific number of things.  When they learn the meaning of two, what they have to learn is the word two applies just in case your system for representing small numbers picks out an individual and another individual, and your system for representing large numbers picks out a set of things, a small set of things.  And then three can be learned in the same way, and then the child can't go any further because the small number system, remember the core system, has a limit of three.

But what the child can do at this point is discover that the progression from two to three and the counting routine involves two things, adding an individual to the set and increasing the cardinal value of the set.  And once they've got that and can generalize that to the other number words, they've worked out the meaning of the counting routine.

Now I've gone through all this because there's no evidence for any of these developments in any nonhuman animal.  This is, I believe, a distinctively human achievement.  And what it consists of, what the child is doing with support from parents but without any explicit instruction by anyone is putting together representations from two core systems with a system of number words and quantification that's emerged through communication with other people through their natural language and their culturally specific counting routine.  And I certainly don't have time to give you this evidence, but there's a wealth of evidence now suggesting that the same three systems are at work in us as adults when we use and reason about natural number concepts.

So the last question I want to ask does experience play a role in this construction?  In one trivial sense it must.  The number words of English are different from the number words other languages, and they have to be learned, but I mean to be asking a deeper question.  Do the concepts that those words pick out emerge, does experience play any role in the emergence of those concepts?

Now I think there's evidence from the research of two educational psychologists, Robbie Case and Sharon Griffin, that indeed experience does play a role.  What they showed first is that in the United States and Canada, although most children from middle class families have developed these number concepts by the time schooling begins, many children from disadvantaged families have not.  In particular, Case and Griffin did a set of studies where first they would take children and have them count and show that all of the children, these are in kindergarten classes, all of the children could count to a nice satisfyingly high number, and then they would take numbers that were in the list that the child had produced, him or herself, and simply ask questions like if I have five apples and you have four apples, who has more applies, testing their understanding that the word "five" picks out a larger numerosity, a larger number than the word "four." 

Now when they asked these questions to children from high or middle income families, almost everybody can answer them.  When they ask them to children from economically disadvantaged families, they got a much lower rate of success in kindergarten.

The next question was why would the kindergarten children from the disadvantaged families be succeeding less?  And one possibility that they pursued was that these children may just not be having the interactions in their homes that middle class children are having and that lead children to make this construction spontaneously on their own.  He found, for example, they found that in middle class families there was lots of talk about number, lots of play with board games, rolling dice and counting up moves and things like that, much less of that in the disadvantaged homes. 

So Case and Griffin designed a series of intervention studies where they simply took kindergartners from disadvantaged backgrounds who tested badly on these number concepts initially and played a set of games with them, a set of board games, no explicit teaching, but played games involving talking about number, rolling dice, counting out moves and so forth and reported dramatic improvements in the children's understanding of number which were followed up in one year and three year follow-ups with dramatic advantages in their formal mathematics education.

So to summarize this, it looks like preschool children construct natural number concepts spontaneously without formal instruction, as long as they're given supportive environments.  Without environmental support, it's not clear that these concepts will develop on their own.  Children who don't develop them then would be at a disadvantage when formal schooling starts, because that schooling presupposes that when a teacher uses the word "three" and the child uses the word "three", they're talking about the same thing.  This failure, though fortunately, the work of Case and Griffin suggests, can be remedied.

Well, I think this general picture applies to many of our most interesting uniquely human concepts, so I could have given a different talk about mental state concepts, concepts like beliefs and desires, propositional attitude concepts.  There's good evidence that infants don't understand these concepts, but that most 4-year-olds do and that children aren't explicitly taught what beliefs and desires are, they figure it out on their own in supportive environments. 

Similarly, for understanding symbols, young children may look like they understand symbols when they point to a picture of a cow and say "cow", but do they really understand that that set of marks on paper is a representation of a cow, a symbol that stands for a cow, not a cow itself.  There's evidence that that understanding is not present in infants, that it develops over the years from two to three or so.  The research of Judy DeLoache; again, distinctively human ability constructed by children without formal instruction, but only in supportive environments, same for concepts of works of art and tools.  So in each case, I think these concepts are developing in the ways that natural number concepts did.  And I think this suggests that this time from age two to five is really a critical time in human development, for the development of a whole host of uniquely human cognitive abilities, abilities that mark us from other animals and also abilities that make us capable of formal instruction.

So what I want to do, I'm probably over time, but I'm just about done, is just end with three general themes and suggestions that I think this work may support, at least that I wish to offer to you to consider whether you think this work might support them.  The first theme goes back to the thing you questioned me about, this preference for novelty.  I think it's the case that as early as we look in infancy, we see that infants are motivated to learn.  Now they're motivated, in part, to learn on their own seeking out situations that give them new information.  But they're especially motivated to learn from other people, and we see this in everything from the following a person's gaze to the objects that they're looking at, to reproducing their actions, to reading through their actions to the intentions behind them.

But I think a possible implication of this work is that while infants are built to learn, they're not built to learn alone.  They're built to learn in interaction with other people who already are immersed in the culture into which they will be growing.  They need social partners to do this, and I think arguably the best social partners to do this would be one or both of the infant's parents.

In that context, I think you might consider whether our society is well advised to give so many parents the cruel choice between having to decide between the economic welfare of their families, on the one hand, and their opportunity to be there as a participating parent during the first year of a child's life, on the other.  Should we be requiring single mothers on welfare to work when their children are infants?  Should we be requiring families that require two incomes to support their children to be choosing between giving their children that economic support and giving the children the presence of a full-time parent in the first year?  I think that's one issue worth considering.

The second theme, which I just ended the substantive presentation with, is that we should pay more attention to the years from two to five, that this is a critical time for children's cognitive development.  This isn't a time when I think we need to be putting children in schools or starting formal education.  It's a time when children are learning great things on their own.  But they're only learning those things in supportive environments.  And I think that suggests a further duty that we may have to children that you may want to consider in this panel, the duty, first of all, of understanding what are these capacities that are developing in the years from two to five, and what kinds of environmental support are necessary for the development of them.  The kinds of studies that Case and Griffin have done for number need to be done, I think, in other domains as well.

      And second, to assure that children throughout our country are able to grow in environments that provide the resources that they need for that development.

The final theme is maybe the most speculative one, but for me, I think it may go the deepest and it takes me back to the first part of my talk in talking about systems of core knowledge in infants.  Now I think that a general conclusion that's emerged over the last 50 years is that to a surprising extent young infants, not always newborns, but 3-month-olds, 5-month-old infants share ways of conceiving the world with us adults, that they experience the world in distinctive ways that are much like the ways that we, as adults, experience the world.  And that's true, I think, in the case of space and objects and other people, the three cases that I talked about.

But there's a way in which infants are radically different from us.  When we experience negative situations, we're capable of acting to change those situations.  When we find our own resources for acting are limited, we can communicate our needs to other people and seek help from them.  But infants, though they share many of our experiences and capacities, radically lack the capacities to act that we have to ensure that their environments are safe and healthy, that they're cared for and that their needs are met.  And I think that gives us the most fundamental ethical responsibility of all, vis-a-vis infants, and that is to care for these creatures who are so like us in our experiences, but so unlike us in their capacities to provide their own care.

Thank you.

(Applause.)

CHAIRMAN KASS:  Thank you very much, Dr. Spelke, Professor Kagan.  The floor is open for discussion. 

Michael Sandel.

PROFESSOR SANDEL:  Thank you very much for that great presentation which really covered an enormous amount.  I would like, if I could, to go back to the question about the looking longer test of novelty, the preferential looking test and what we can infer from it. 

Thinking back to that two by two diagram that summarized the study of children's perceptions of what makes inanimate objects and people move, contact in the case of inanimate objects, goals in the case of people, it's a lovely result, so lovely that it's also a suspicious result because what it discovers is that the way children perceive the world and the laws of movement recapitulates the 17th century split between explanation in the physical sciences and in the human sciences where we concluded in the last 300 years that mechanism governs the movement of inanimate objects, not teleology.  But the teleology or goal-directed explanations govern the human sciences, the way people behave, and it just turns out, lo and behold, that children naturally, so to speak, perceive that relatively recent discovery, the way that the modern science has bequeathed this split between the modes of understanding in the physical and human sciences.  So this is really to explore that suspicion. 

What's the warrant for inferring from the looking longer test one thing rather than another?  And here's another experiment, and I wonder what you would read from these results.  You can imagine you could time, never mind children, even adults, how long some adults might gaze at the sunset or the rising of the sun as those events naturally occur, familiar though they are, not novel.  People gaze sometimes for long periods of time out of appreciation or contemplation or who knows what.  And then suppose you, as the counter example, you did an experiment of the kind that occurs in the movie, The Truman Show.  You remember in The Truman Show, unbeknownst to Truman, he was the character, the Jim Carrey character.  He's living within an elaborately constructed television set where everything, including the seasons and the weather and the rising and the setting of the sun is governed by a producer who's in a control room.  And at a certain point this fiction is maintained, but at a certain point the producer, they're desperately looking for Truman who has escaped, but it's the middle of the night.  And they can't find him, and so the producer decides he has to spoil the fiction in order to bring up the lights.  And he says "cue the sun," and the sun rises in the middle of the night.  That would be novelty.

Now suppose you timed, you applied the looking longer test to the sun that arose at that unnatural moment, unfamiliar moment, would people, infants or would we—would you expect that we would look longer at that unnatural, unfamiliar rising of the sun, than we do when we sit in contemplation of a natural sunrise?  And how would you know if we looked longer at the one rather than the other that one was novel and the other familiar?

PROFESSOR SPELKE:  Right.  Actually, in that case, I think we probably would.  If the sun suddenly rose in the middle of the night, I think we'd all run outside and look at it.  However, I completely grant your general point.  And in fact, the reason I went through the whole discussion of the Held experiments is that for any given behavior that an infant chose, looking longer at one thing than at another, we could tell multiple stories about the causes of that behavior.  That's absolutely true.

So one thing that I had to do in making this presentation because I wanted to cover a lot of ground was give you the results of single experiments, but it's when you look across experiments that I think the following things emerge.  First of all, it is not the case that infants will absolutely and under all circumstances prefer novelty.  That's not true any more than we as adults will always prefer novelty.  Actually, one case I think in which it's least likely to be true is cases involving human action where if other people do things that are bizarre, we may avert our eyes from it rather than look at it.  So it's not at all the case that one can take as a given whenever an infant looks longer at something, that must be more novel to them.

However, within a series of experiments what you do in these studies is the following.  You start with an analysis of an ability.  Under what conditions would we, as adults, see something as goal-directed or not.  Then you make a set of focused predictions about what you would see in an infant if they had the same system for representing things as we have.  And then you test down the line whether those predictions hold.  Now if you get a coherent pattern across them, all involving when you change something in a way that would lead an adult to say that's funny, the goal just changed, the baby looks longer. 

Across that series of studies, there isn't a coherent explanation to give if the baby were preferring the familiar one and there is a coherent explanation to give if they're preferring the novel one.  So that's one answer to your question.

The other answer to your question, though, is that both in the case of research on infants' reactions to people and in the case of research on infants' reactions to inanimate objects, the examples I gave were all preferential looking experiments.  But in fact—actually, they weren't all.  In both cases, multiple methods have been used to converge in on the same abilities.  So for understanding infants' representations of other people's actions, you can use imitation tasks where they repeat people's actions and ask is their repetition true to the goal or is it true to superficial properties of the actions?  And the answers you get from those studies converge with the looking time studies. 

Similarly, in the studies of object representations, you can ask what do babies see as the bounded objects in a scene, either using preferential looking with the assumption of a novelty preference or by using reaching, and you see a convergence across them.  So I think in both cases it's the converging findings of series of studies within each method in relation to adult abilities and also series of studies across methods that lead to these conclusions.  And you're quite right, that if you single out any single experiment, then you're in the situation that Richard Held was in when he only had the first experiment on the 4-month-old infants looking longer at the side with double image stripes than single image, and you don't know what the basis of the response is.

CHAIRMAN KASS:  Bill Hurlbut.

DR. HURLBUT:  If our question here, fundamentally, is nativism versus empiricism, I want to ask you about the sort of fullest form, that being the development of the moral mind, because building on what Michael was just talking about, I believe there are studies that indicate that infants will look at things, certain things, longer than others based on what you might call intrinsic value.  So, for example, you mentioned faces.  There are studies that indicate that certain faces rated as attractive faces by adults and across cultures command the longer attention of infants.  Now that's really amazing.  That means somehow—and this is quite early infants, I believe.  Some sort of pattern, and it's not just symmetry, some pattern has an intrinsic value.  It's built in, it would sound like.  And that's the first thing.  I'd like you to elaborate on that.

The second thing is not just intrinsic value, but the roots of our relationship between awareness and action.  You cited Meltzoff's work of imitating faces.  When you stop and you ponder that capacity, that again requires that the infant somehow has a pattern that it knows sensorially how to apprehend, but also how to reproduce.

Now I know there are some findings that suggest there are cells, Rizzolatti's so-called mirror cells that could mediate this.  But it would imply that quite high order constructions that somehow there was already a connection between sensory input and motor action.  And of course, the concomitant of that is that if there is motor action, even with a sensory input, that the subjective states that accompany those muscle actions would already be communicated in a kind of inter-subjectivity.  All this seems to add up to a foundation for the moral mind.

Can you just comment on all of that?

PROFESSOR SPELKE:  Sure.  On your last point first, I think there's actually quite rich evidence that babies are sensitive really early to the correspondences between their own actions and other people's actions.  One thing I didn't talk about from the Woodward studies is that if you look at the kinds of actions that babies can attribute goals to, they develop hand in hand with the child's own capacities to act.  So it's at the point at which a child, him or herself, will start pointing to objects, that they will interpret a pointing action that they see another person perform as goal directed by the Woodward test.  So I think that goes along with your line of thinking.

And you're also quite right that we don't know whether this is unique to humans or not.  There's clearly pieces of it in monkeys as shown by the Rizzolatti work and other work like that.

I'm going to have to punt on the morality question, not because I don't think it's important, but because I really think that the jury is out.  There are hints of pieces of what will become a system of moral reasoning that I think we can discern in infants, but whether we have a full blown system that's showing itself in a glimmer here and a glimmer there, or whether a full blown system of moral sense is going to require the kinds of constructions that a system of numerical reasoning requires, constructions that children will put together, perhaps without explicit teaching, perhaps learning by example and by observing other people.  I think we just don't have the evidence at this point to say.

There's, of course, a long tradition of studying moral development in children.  I think unfortunately much of that tradition has focused not on children's moral intuitions, but on their justifications, and then what you find, not surprisingly, is that young children who are pretty terrible at giving coherent justifications for anything they believe, don't give very sophisticated looking moral justifications either.

But the question of whether they have underlying intuitions, like our intuitions as adults and whether there's a core to morality is, I think, going to be a very interesting and important question to pursue, and we don't have the answer yet.

DR. HURLBUT:  Can you say at least a little bit about intrinsic value, like beauty in faces?

PROFESSOR SPELKE:  Here I want to voice some of the skepticism I think related to what Dr. Sandel was saying before.  We can say that a baby will look longer at one thing than another, but do we know that that means that they're esteeming it, that they're endowing it with value?  I'm not sure that we do.  But maybe Jerry—I think this goes out of my domain of sort of cold cognition and into emotion, and maybe Jerry wants to speak to that?

PROFESSOR KAGAN:  Babies prefer symmetry.  I thought Liz was going to say that actually, and that's why, they prefer vertical symmetry so I agree with Liz.  They don't understand beauty or that that face is pretty, but they will look at vertically symmetrical designs, and pretty faces are vertically symmetrical.

Incidentally, that doesn't mean that I don't believe that biologically human children don't inherit a foundation for moral sense.  They do somewhere in the second year, but I don't believe they have it in the first six or eight months of life.  They get it later.

CHAIRMAN KASS:  I have Janet, Ben Carson, Mike Gazzaniga and then myself.

DR. ROWLEY:  I actually have three questions, if I may, two probably for Liz and one for Jerry.

So neither one of you actually talked about the change in the complexity of the brain connections that develop over time and focus really, you focus on early cognition which is certainly important, but all of the evidence, of course, which I know you would agree with, that the brain certainly matures over a long period of time and so there are certain kinds of skills that children should be exposed to and experiences they should get relatively early, but then there are other things that are going to evolve later, and trying to force a child to learn some things at three or four is futile or frustrating.

Would you say a little bit more just in general about conductivity, and then I've got two more parts.

PROFESSOR SPELKE:  I agree completely, and I think one of the values of the work on cognitive development is there's a huge gap between what we understand about learning and cognition on a functional level and what we understand about neural growth and conductivity on a structural level.  So I think that the beautiful work on neural development tells us to expect that children will be optimally ready to learn different things at different ages, but it doesn't in itself yet tell us what things they're ready to learn at what ages, and we need the behavioral work to do that.  And I quite agree with you.  For example, based on the work that I presented on number, I think it would be futile at best and possibly harmful to be pushing infants or very young children to be developing mathematical concepts before they even have a system in place for representing them, and I think there's many cases of that where we can use work on basic cognitive development to make more informed decisions about what children are ready to learn at different ages.

DR. ROWLEY:  Now the other—one of your final concerns or practical consequences of what you've described was that it's very important for parents to be able to be with their children for the first couple of years of life and you weren't really in favor of child care at that point.  But the concern is that there are, unfortunately, a fair proportion of families in the United States where the parents themselves are not really in a position to give the children these kind of early stimuli.  And so I wonder if there isn't really a place for child care and nursery schools at a very, very early age for—at least some availability for these, some portion of the population.

PROFESSOR SPELKE:  Thank you for that clarifying question.  I did not mean to be arguing against child care.  I mean to be arguing that every infant needs to be growing up with adults who are responsive to them, who have the time to take to be interacting with them, to be attending to them, that infant development doesn't happen in a vacuum.  And in many cases, it's the parents who would want to be playing that role if it were economically possible for them.  But that is not to say that a biological parent is the only person who can play that role.

DR. ROWLEY:  And finally, the question for Professor Kagan, when does a sense of right and wrong or moral judgment really develop in children?  It's partly a question that Bill asked, but we didn't get into—when can you really hold a child responsible and what kind of actions can you hold them responsible for?

PROFESSOR KAGAN:  Three stages in moral development which I believe are universal.  In the middle of the second year, if you're late by, I don't know, 30 months, but most kids by 2, understand the concepts right and wrong, good and bad, in their language.  They have a concept of prohibited actions.  That's not morality, but that's the beginning.

Between five and seven, and that's why the Church and English Common Law and Freud and Piaget, I mean everyone knows that a profound change in brain occurs between five and seven.  We don't know what it is.  Now children have a more abstract concept of good and bad and understand that going to school is good and watching the cow from 9 until dinner is something I should do.  Now we hold them responsible.  And the last phase is at adolescence, again, I think a maturational change occurs, of course, all supported by the environment.

Now one has, one looks for consistency and one looks for consistency in your beliefs which 7-year-olds don't.  So the child of seven can hold these beliefs.  My father is a wonderful man.  My father is much too harsh with my mother.  One of those has to go.  That's the change in adolescence.  Now the adolescent seeks consistency among their moral premises, and that's the last phase maturationally.  Of course, experience and culture—morality is like language.  You're given the capacity, and now you're culture teaches you whether you're going to learn Swahili, French or Germany, and your culture teaches you, with the exception, I think, of unprovoked aggression.  I have the intuition that that is universal.  But with that exception it teaches you what is moral and what is immoral. 

CHAIRMAN KASS:  Ben Carson.

DR. CARSON:  Thank you both for those illuminating discussions.  This morning we talked a little bit about the neurophysiological and anatomical aspects of the developing human brain and this afternoon more about some of the cognitive social developmental issues.  In both cases, there's an implication that the nurturing environment plays a very significant role, it provides very significant advantages.  I was particularly struck by the slide that indicated the numerical reasoning at a 95 percent versus an 18 percent range in children in nurturing environments versus those in lower socio-economic classes.

The question is is there a point at which it is too late to close the gap?  If so, what is that, and secondly, how do you explain late bloomers?

PROFESSOR SPELKE:  Both really good questions.  The work of Case and Griffin is actually, I think, very encouraging here because although the middle class children tend to develop these concepts in the years from two and a half to four, their intervention was aimed at 5-year-olds starting kindergarten and it was not too late.  The 5-year-olds in their program did extremely well.  That doesn't tell us is there a point later on that is too late.  There will be a cumulative problem though if you wait too long which is that when kids start elementary school, they're getting exposed to a whole curriculum that presupposes that those concepts are in place.  So if the concepts aren't in place, even if the child is biologically still capable of gaining them, they're going to get further and further behind because what the teacher is saying is just not going to be making any sense to them.  So I think just on those grounds one would want, these kinds of building block concepts, one would want interventions that put them in place at the time that formal education begins.

On the issues of late bloomers, I think there's lots of reason to think that nature is flexible and there are many paths to success and many different rates and patterns that children will follow to get there, and I don't think it follows from any of the work that Jerry or I talked about today.  In fact, certainly not what Jerry talked about, but not the work that I talked about either, that there is one royal road that one must progress down and one specific time table to get there.

PROFESSOR KAGAN:  There's a difference between the ability to reason and where you are in the rank order.  And this is where you are in the rank order.  A great moment for me when I had a sabbatical leave 30 years ago was to sit on the edge of Lake Atitlan in northwest Guatemala with illiterate Mayan Indians who had no schooling and asking 12-year-olds what would happen if the lake dried up and getting perfect syllogistic reasoning.

I agree with the thrust of Liz's talk.  I mean, look at the conditions under humans grow up.  We have to have a basic set of cognitive abilities, but in our societies, technological societies, it doesn't make any difference how good your reason, that's irrelevant.  It's where you are in the rank order because we can have just so many chiefs, and that's the problem.  We don't want to confuse that.  We don't want to confuse the class differences in rank with the ability to reason.  That would be very dangerous.

CHAIRMAN KASS:  Mike Gazzaniga.

DR. GAZZANIGA:  Are you sure we have the time?

CHAIRMAN KASS:  No, go ahead.  Let's take just a few more minutes because we don't want to lose again the benefit of having some questions.

DR. GAZZANIGA:  First of all, I hope everybody appreciates how Jerry and Liz asked these fundamental questions of biology in the most low tech imaginable way with looking longer at a stimulus.  You didn't get into the peek-a-boo experiments, but they're as captivating.  And sometimes I think we should throw our brain scanners out and just give the field to these two and have them answer questions for us.  But once you get past the critical period issue here and where you might have said constructionist ideas were needed to bring the kids along to get them up to the sort of the level of conceptual development that you might just call baseline normal level, but then you've introduced this idea of the social context, so you really don't know what it is that's going on.  Something is going on that's needed in a group of kids.

Now let's imagine that we've got our group of kids up to the baseline level.  And now you're trying to introduce other concepts where people start to differentiate in their understanding of the world.  So you want to teach Newtonian physics versus our natural naive physics.  What then?  What are the tricks you have up your sleeve?  Are there tricks up your sleeve that can bring along the next level of conceptual thinking, and is there a level, a definable level where you start seeing separations that are very hard to overcome on any social group?

PROFESSOR SPELKE:  Yes.  One of the things that I was sorry to have to leave out of my already too long talk was the evidence that when adults reason about number or physics or other things, we bring together the same core systems that we see children using when they assemble these concepts in the first place.  I think the general answer to your question is that at any point in the educational system the way education works is that it builds new concepts out of old concepts and that the way to get a child, a high school student, to understand Newtonian mechanics is not to ignore their intuitive notions of mechanics which are profoundly not Newtonian, right, there's no action at a distance and so forth, not to ignore them but to work with them, to work with them and to build on them and then by connecting them to their intuitive number concepts, to see that there's a problem with them.  And that there's another way of thinking about how objects move, building on what you know about number, that does a better job than your intuitive notions of how objects move, building on this kind of Medieval or Aristotelian notion of things in motion and giving forces to each other.

So I think at every step of the educational system, good teachers intuitively figure out what people's pre-existing concepts are and work with them.  And because in many cases, especially early on in the educational system, it can be extremely difficult to intuit what the concepts are of a child when they're different from yours.  The research can be helpful in helping teachers to understand and that can be helpful for designing curricula that takes those concepts and build on them.

CHAIRMAN KASS:  I'm next in line.  I want to make a comment and then a question.

The comment is partly inspired by Mike's question and your answer.  I understand that the core knowledge is somehow the foundation and one builds upon that, but there really might be certain kinds of real discontinuities and in the area of number you'd have the primary case because the modern concept of number bows the difference between a multitude and a magnitude so that you have a number line to which—a Greek would find it unintelligible. 

A number is a discrete multiple and to have a line in which each point is somehow a number and that you blow the difference between the discrete and the continuous is strange.  And you've got to somehow overturn your fundamental idea of multitude in order to acquire the modern idea of number, but that raises some kind of question about the difference between the things which are somehow naturally ours and the things which are somehow acquired as a result of new conceptual schemes, and some people have a hell of a time learning algebra which is based really upon our Cartesian coordinate system. 

The question and you can comment on that if you'd like, but the question really has to do with the division of labor in this discussion between the cognitive capacities, and let me give to Jerry Kagan not just questions of temperament, but also emotion, motivation and interest.  And I wonder whether this perfectly respectable division of labor doesn't introduce—isn't based on a kind of distortion in which the question is whether crucial to cognition are not just the native capacities for discrimination and awareness, but interest, desire, motivation and concern. 

One could talk about the game playing way of remedying, a board game way of remedying the difficulties in numerosity either as the acquisition of cognitive ability or as actually caring about the matter because there's winning and losing involved and somehow certain kinds of things now come to the fore.  So I'm wondering whether this sort of bifurcation of cognition and motivation or cognition, temperament, emotion and drive, whether that's an accurate representation of how we should be thinking about how children learn. 

Aristotle's remark "all children by nature desire understanding," that's somehow put all human beings, but begins really in childhood.  And I just wondered whether you would comment on how the two sides of the street meet in your own understanding of what we're talking about here.

PROFESSOR KAGAN:  Yes, I'll be brief, and then Liz might want to add.  I don't think temperament has anything to do with it, but emotion does.  As Liz intimated earlier, all humans as a species enjoy mastery.  That's not a new idea.  They enjoy understanding and enjoy using their talents at the next level of challenge.  But we can't run a society that way.  That is, each society has a set of requirements, and we know the requirements for technological societies.  They require reading, mathematics, writing essays.  Those aren't the tasks that come naturally.  So we are forced, we must say to children, I'm sorry, these are the tasks that you have to master.  They are less natural to the human species. 

Now we need motivation, special motivation, acquired motivation.  This is what Liz was driving at, why we need parents.  And because no human being, child or adult, will invest energy at a task they do not believe they would be successful in.  An animal won't do it, and a human won't do it.  So once you have a child in grades one, two, three and four who comes to the decision every child able to do this except those with a damaged brain, that there's no way I'm going to be in the top third of my class.  There's no way that I'm—because there's no idea of absolute skill.  It's always relative, right?  The adults and the peers determine what is called mastery.  And so by grades four or five you lose motivation.  That is the boat we're in and so the task is not to say yes, we won't teach you any reading, what do you wish to do?

The task is to devote more effort to the children who are behind.  And now my last point, not just in America or Europe, in every country, every country where this study has been done, the lower the educational level of the parents, the poorer the academic record, period.   Class is everything. 

There are studies.  NIH spent $50 million on the effect of various forms of day care, home care, home alone.  This is a very famous study.  And when you look at the data, the best predictor of cognitive performance in the second grade is the class, and after that everything else has trivial variance.  This is the issue that we have to deal with.  It's profound.  It's not just—it's our problem in America, seriously, but it's a problem around the world, and we have to get—we have to communicate, we have to do more for those who are less well educated in our society to get them to understand the importance of the task requirements we set for children in our culture.  They don't understand it.  Many of them are fatalistic.  That is a very difficult job. 

Now speaking for myself, I can imagine no more important task this nation might undertake, no more important task.

PROFESSOR SPELKE:  Let me just add that I think—I agree with what Jerry said, but I think that in addition to children having an intrinsic desire for mastery, there's an intrinsic desire for connecting to other people for becoming able to do the things that other people are doing and that this is driving much of the observational learning and of coming to gain the skills that mark the people in their community and in their culture and that, on that basis I completely agree with you. 

Certainly in the preschool years, the division between cognition and motivation or emotion which is useful for figuring out how to organize talks is quite artificial, and any program aimed at children to enhance their cognitive development is going to need to be building on these needs intrinsic to children to be connecting.

If I can just say one thing quickly, though, about the point you made about number, one of the reasons that number is so fascinating is that both in the history of mathematics and in the education that children and high school students and college students go through in studying mathematics now, we see a progression of revolutions in the concept of number.  I think the first revolution is the one I talked about between age two and a half and age four, where children go from having two quite different notions of number, neither of which has the power of the natural number system to constructing the natural number system.  And although this is partly an expression of faith and only partly based on data, I also think that if we turn to the later constructions, understanding of number lines, constructing notions of rational numbers, real numbers and so forth, the general story that one advances to a new level of understanding by taking one's pre-existing understanding, in this case we'd have to look at understanding of points and lines and spatial intuitions, which I didn't talk about at all, but which young children have.  One takes these, one connects them in new ways and often with the help of teachers who can point out what connections are useful, what properties of points and lines are useful in thinking about number?  You then get to a new level of development.

CHAIRMAN KASS:  Briefly, Robbie and then Peter and then we'll break.

PROFESSOR GEORGE:  Thank you.  Anyone who has been a parent or even an older sibling knows what a pleasure it is to observe the reactions that children have to various things.  It must be wonderful to be able to do that in a professional capacity as well and be paid for it.  And, of course, it was very interesting material that you presented to us from so many sources.

My impression is that—I want to ask you about something that hasn't been raised yet, which is research ethics.  My impression is that while anyone who works with human subjects is working under fairly strict ethics rules, that when it comes to working with children there are an even richer set of ethics rules, and I wondered if you could say a little bit about them, and I'm particularly interested to know whether the ethical norms that apply in working with children are truly salient or whether they're mostly or merely symbolic.  In other words, do we sacrifice some knowledge?  Do we sacrifice some advances for the sake of respecting those norms that are meant to protect children?

PROFESSOR SPELKE:  Yes, we do, and I think it's an excellent thing that we do, and one can't subject children and one shouldn't subject children to any of the controlled rearing studies that one can do on other animals.  One would be very wary of subjecting children to any kind of stressful situation.  I mean, our own rule of thumb for our experiments is the parents are always present during the studies.  They should be completely happy at every second for what's going on, with what's going on in the study.  It should be the kind of events that go on in children's lives or that the parents would want to see going on in children's lives outside the lab.  So I think the standards are very high, particularly for research like mine where there is no immediate benefit to that child.  We're asking basic questions about the development of human knowledge.  We hope that the answers to those questions will be a benefit to society, in general, but we have no illusion that the particular child who comes in for our study is going to benefit.  So they better have a very good time and experience no negative consequences from being in the research.

PROFESSOR GEORGE:  Now in foregoing some knowledge for the sake of respecting ethical norms, the norms themselves, I take it, cannot be supplied by science or by scientific reasoning?  Is that right?

PROFESSOR SPELKE:  I don't know about the history, how the ethical norms developed actually.

PROFESSOR GEORGE:  In other words, are they themselves the fruit of scientific inquiry or are they—do they come from another source?

PROFESSOR KAGAN:  No, they come from the consensus of a society that one does not cause distress.

PROFESSOR GEORGE:  And that itself is not a scientific—is it a rational concern?

PROFESSOR KAGAN:  Moral choice.

PROFESSOR GEORGE:  It's a moral choice, but one that comes to science from the outside.  Okay.  thank you.

CHAIRMAN KASS:  Peter's last comment.

DR. LAWLER:  On the basis of what you said, couldn't you argue that they could come from what we know about the distinctive nature of children?  They could come from science, right?

PROFESSOR KAGAN:  I'm sorry, I didn't hear the question.

DR. LAWLER:  The moral norms, the ethical norms, why couldn't they come from—what you two do in such a great way is restore the idea of a distinctively human nature.  We're distinctive in many respects, but we're also natural beings.  We have these potentials which are actualized, right?  So given all that we know about the nature of children in some ways as distinct beings, social beings who take a joy in learning and everything you've said, why couldn't the norms come from what we know through science?

PROFESSOR KAGAN:  I hope you meant that to provoke me.  I hope I speak for Liz.  Science is a wonderful thing.  It's one of the great, great human missions, and those of us in science feel privileged. 

Do not look to science for moral norms.  Science tells us that male primates are promiscuous, therefore we should change the norms of adultery?  No?  No.  Science tells us that most boys are much better at spatial problems like geometry than girls.  Therefore, we probably should have sex segregated classes for teaching geometry.  A referendum next November would be defeated by Americans who are wise.  Wittgenstein understood this.  The ancients understood this.  Jim's written about this in his book The Moral Sense. 

Morality is very special.   Very special.  It has to do with the sentiment of community, and that lies outside science.  We want to say to the scientists the following.  Thank you.  Those are very interesting facts, very interesting, but in this instance I don't choose to implement them, and that's neither silly nor dumb.

CHAIRMAN KASS:  We're going to stop.  Thank you both, very, very much for a wonderful afternoon and also for the work that you're doing.  This is really eye opening and very important foundational work that will, I'm sure, benefit all of us.

To the Council Members, we're behind as we so often are.  We had left the last hour, it will now be closer to half an hour for stock taking and discussion of development here.  I see there are motions to adjourn.  We can't partly because this Ethics Council is required by law to be instructed about ethics.  We had an ethics lesson the very first time we met.  I think we escaped by somebody's inattention.  I think we require these annually, do we?  And someone forgot to give us lessons in ethics last year, but someone will be arriving at 5:15, so you can't leave.  We'll take 15 minutes.  We'll talk amongst ourselves.  Thank you to our guests.

(Applause.)

(Off the record.)