Perception and Action Projects for Classrooms

These projects are designed to demonstrate perceptual illusions and behavioral adaptation in the class room setting.

The Effects of Inversion on Pattern Recognition

Due to Earth's gravity, we learn to recognize faces and facial expressions in an environment in which we are normally upright. However, in space where there is no gravity, astronauts can pass by one another in many different orientations.

These examples illustrate the effects of inversion on our perception of signs, objects, and human faces.

One of the astronauts is holding a sign.
What does it say?

Are you sure? Click here and find out...

Face Illusion

On Earth, we learn to use facial expressions effectively during the communication process. When faces are not upright, mistakes in communication may occur because it is much more difficult to recognize subtle distinctions among faces and facial expressions.

Are you sure? Click here and find out..

Was it more difficult for you to decide which face was happy when the faces were inverted? It usually takes longer to process the information because we are accustomed to seeing upright faces.

You have just been a victim of the orientation effect...ready for more?

Margret Thatcher Illusion

Are you sure? Click HERE and find out..

Surprised? You probably couldn't tell that something was wrong with the distorted face until you rotated the images 180 degrees (upright). Actually the distorted face begins to look hideous when rotated 90 degrees from the upright position. This is known as the Margaret Thatcher Illusion.

Pitch Room Illusion

The terms vertical and horizontal are orientations with respect to gravity. Walls are usually vertical and floors are usually horizontal. When walls and floors are not vertical or horizontal, they can dramatically affect our perception. When a room is pitched upward, a person who is standing against the far wall of the room seems shorter. When the room is pitched downward, the same person seems taller. The pictures below show this effect.

Are you sure? Click here and find out.

If you measure the height of the man in each of the pictures above you will know that it is the same. When the background is tilted left or right, backwards or forewards, people do not seem to be standing upright. NASA is interested in the effects of altered visual environments as they relate to the perception of size, orientation, and location.

The Muller-Lyer Illusion

To perform this task you must make a moving Muller-Lyer tool. If you would like to make your own Muller-Lyer tool, go to this link, and print out the images. Cut out figures 1 and 2, then insert Tab A into Slot B. When you are done with that follow the instructions below.

Step 1: Make the horizontal lines appear to be the same length in figure 1 by sliding the right hand side either in or out of the left hand side.

Step 2: Use a ruler to see if you made the horizontal lines the same length. If you did, move onto step 3. If not, try again.

Step 3: Make the horizontal lines appear to be the same length in figure 2 by sliding the right hand side either in or out of the left hand side.

Step 4: Use a ruler to see if you made the horizontal lines the same length. If they are the same length you are immune to the Muller-Lyer illusion. If they are different lengths then you fell victim to the Muller-Lyer illusion. Please read below.

Your eyes were tricked by the Muller-Lyer illusion. The arrows on each end of the lines make you perceive the line to be either longer or shorter than it really is.

Although we are not explicitly interested in the Muller-Lyer illusion, it does serve as a good demonstration of how the senses can deceive a person. The way a person perceives the world may not always be an accurate portrayal of how the world really is. It is particularly important in the space program to ensure that astronauts correctly perceive the world around them so that they can act appropriately to a given environment or situation.

Visual Adaptation Task

To perform this task you must have a prism, and a target. The target can be any stationary thing, if you wish you may use the NASA meatball.

Read the full instructions before proceeding.

Step 1: Stand at arms length from the target. Let your hand hang at your side and step back an inch or two. Next, reach very rapidly and point at the vertical line with your right index finger. Let your right hand come to your side. Were you able to point at the target?

Step 2: Put on the prism goggles. Let your right hand hang at your side, and again reach out as quickly as you can and try to point at the target with your right index finger. IT IS VERY IMPORTANT TO POINT AS FAST AS YOU CAN. Put your right hand back at your side.

What happened?

Step 3: As quickly as you can, reach out 20 times and try to point at the target as you did in Step 2. Remember to put your right hand back down at your side each time after you have pointed at the target.

Did you get better with practice?

Step 4: Now, take off the prisms and quickly point at the target with your right index finger. What happened now?

The task that you just performed illustrates how quickly humans can adapt and readapt to altered environments. When you first put the prisms on, your visual and motor systems needed to adapt to the new altered environment. You probably noticed that after a few attempts of pointing at the target, you had little difficulty. However, once you removed the prisms, your ability to correctly locate the target was impaired because you became adapted to the altered environment. Now reach again for the target. Can you correctly locate it? Your visual system has recalibrated itself again. You have just experienced an adaptation similar to one that astronauts experience when they go into space and when they return to Earth.