| How to Obtain
Documents |
| |
| NCJ Number:
|
NCJ 202093
|
| Title:
|
Objective Assessment of Comparison Question Polygraphy
|
| Journal:
|
Polygraph Volume:32 Issue:2 Dated:2003 Pages:107 to 126
|
| Author(s):
|
Vance V. MacLaren ; Donald J. Krapohl
|
| Publication Date:
|
2003 |
| Pages:
|
20 |
| Type:
|
Studies/research reports |
| Origin:
|
United States |
| Language:
|
English |
| Annotation:
|
This article reports on a system for quantifying
psychophysiological information obtained in comparison question
polygraph tests (CQT's) that was developed on a sample of 181
confirmed deceptive and 150 nondeceptive field cases. |
| Abstract:
|
The CQT uses a dynamic interview procedure in which stress
responses to questions are observed. At least two classes of
questions are present in a CQT exam. Relevant questions
(questions related to the event at issue) may be answered with
either deceptive or nondeceptive "yes" or "no" answers, and they
are compared with a baseline of physiological responses
established by presenting "comparison questions." The comparison
questions are phrased in such a way that subjects feel they must
be deceptive to complete the exam successfully. Comparison
questions are intended to thereby elicit emotional arousal in
both deceptive and nondeceptive suspects. The system proposed in
this article uses permutation tests to obtain separate estimates
of the likelihood of deception and nondeception for individual
cases. These probabilities are then combined with base rate
information to calculate an overall probability of guilt for each
case. Assuming a 50-percent base rate of deception and
conservative cutoff points for assigning deceptive (p=.90) and
nondeceptive (p=.10) outcomes, 91 percent of deceptive cases
(N=152) and 98 percent of nondeceptive cases (n=128) with
conclusive outcomes were correct. The system was cross-validated
on four groups of field cases. Conclusive outcomes were correct
in 90 percent of deceptive cases verified by confession (n=97),
in 92 percent of deceptive cases verified by urinalysis tests for
drug infractions (n=49), and in 64 percent of deceptive cases
independently verified by physical evidence or subsequent
confession not associated with the polygraph test (n=11).
Conclusive outcomes were correct in 88 percent of independently
verified nondeceptive cases (n=16). The system was also
cross-validated on a sample of laboratory cases drawn from three
separate experiments. In the lab samples, 88 percent of
conclusive outcomes were correct for both deceptive (n=33) and
nondeceptive (n=25) groups. The proposed scoring system
circumvents several logical problems with traditional approaches
to quantification in CQT polygraphy. It also provides an
effective means of obtaining accurate classification in
approximately 90 percent of cases. 11 tables, 1 figure, and 33
references |
| Main Term(s):
|
Technology |
| Index Term(s):
|
Polygraphs ; Polygraph techniques ; Investigative techniques ; Polygraph reliability |
| |
To cite this abstract, use the following link:
http://www.ncjrs.gov/App/Publications/abstract.aspx?ID=202093
|
* A link to the full-text document is provided whenever possible. For documents
not available online, a link to the publisher's web site is provided.
|
|
Help | Contact Us | Home
