第121章
(See Kleinmutz, B., & Szucko, J. J. (1984). Lie detection in ancient and modern
times: A call for contemporary scientific study. American Psychologist, 39, 766776.)
The results of this study (and others mentioned in the article) might be contrasted with the conclusion
promoted on the TV program “Lie Detector,” hosted by lawyer F. Lee Bailey (1983-84 season). The promo for
the show said it “gets to the truth . . . The path of justice can make a bizarre turn, a path that perhaps can be
411
straightened out on . . .”
FREUD AND FREE ASSOCIATION: REACTION TIME AND BODY TALK
Long before the polygraph was put into practice, psychologists utilized other techniques for uncovering
what a person was trying to conceal. Freud used the technique of free association as a means of discovering
ideas that the patient had distorted through transformations of affect or attachment to other ideas or had
put out of awareness.
Reaction time has long been used as a measure of decision processes. An assumption of this technique is
that the more complex the decision, the longer cognitive processing takes. If the cognitive processing of
negation of a truth (lying about one’s known guilty acts) takes longer than affirmation, reaction time should
be useful in this detecting guilt task.
Finally, we express much about ourselves through our “body language”, the nonverbal, physical reactions
of our movements, gestures, and facial expressions. (See Mehrabian, A. (1972). Nonverbal Communication.
Chicago: Aldine-Atherton.)
A wonderful resource that should definitely be read before this demonstration is a theoretical and empirical
study by Bella De Paulo, Julie Stone, and G. Daniel Lassiter (1985), “Deceiving and detecting guilt.” In B. R.
Schlenker (Ed.), The Self in Social Life. New York: McGraw-Hill. The article deals with the informativeness of
verbal and nonverbal cues in the communication of deception, the role of motivation, gender, and actual
deception versus perceived deception, and many more fascinating issues for discussion. There is also an
ample bibliography of more than 100 references relevant to various aspect of this phenomenon.
In this demonstration, three measures of emotional disturbance will be used: word associations, reaction
times, and expressive behavior.
Procedure
Two male students will engage in a role-playing task designed to make one of them feel guilty about having
murdered a woman who was blackmailing him. The guilty student destroys the evidence, including her
photo, by burning it, and then tries to conceal his guilt from everyone. (Students often feel guilty about the
act of burning the letter and photo; some keep the photo, especially if you previously have had it
autographed with the name of the person you selected—then they really feel guilty.) The innocent student
receives instructions to get a drink of water to relieve the thirst he is supposed to be experiencing.
The class is cast in the role of “psychodetectives” trying to uncover the truth. They might be psychologists
hired by the court, experimenters, or jury members. The final decision centers on determining which of the
two students is guilty and on what evidence that inference rests. It is interesting to look at “false
negatives”—believing the guilty subject to be innocent, and “false positives”—believing the innocent one to
be guilty.
Materials
You need to provide a stopwatch, two envelopes, three matches, and a metal pan. You are given two letters,
a woman’s photo, a word list, data sheet, Expressive Behavior Encoding Guide and Tally Table, work
association norms, reaction time table, and verdict slips.
Having several stopwatches and calculators would be helpful.
Subjects
Three (or four) for pretesting, two to participate; rest of class to be given research tasks.
Time required for Research
25-30 minutes for data collection; 10-20 minutes for analysis and verdict.
Time Required for Discussion
10 minutes before demonstration; 10-30 minutes after. (This section could be extended over two class periods.)
Method
1. Before class, prepare two envelopes. One should contain the instructions designed to introduce
413
guilt; the other contains innocuous instructions (see letters at the end of this section). The envelopes
should be identical. In the guilty letter, you must indicate a safe place where the subject must go in
order to perform the guilty act; you must also make the necessary preparations of having at that
place: (a) Three matches, (b) a “blood-stained” (red inked) envelope containing the victim’s photo
(any photo of a woman will do), (c) a metal pan in which the envelope can be burned. (Find a
relatively secluded spot for the guilty suspect to burn the note and picture. One of our section
leaders found to his dismay that a janitor had thrown the envelope away shortly before the section
meeting; another suspect was interrupted by the sound of the fire alarm, set off by a very sensitive
smoke detector. These problems can be avoided by careful planning.)
3. Bring a stopwatch to class.
4. Select two male subjects at the beginning of the class (it is possible to use two women as suspects;
you might then want to make some changes in the content of the letter the guilty one gets).
Premeasure the RTs of three early-arriving students on each of five premeasured words (see Word
List). Select the two with most similar Reaction Times (RTs) in order to minimize individual
differences in speed of reaction to neutral words. If all three vary considerably, test a fourth and use
the two who are most comparable. It is crucial that the suspect try to conceal his guilt; pick students
you believe will play the part well and remind them to carefully follow all the directions they will
receive. Give one unmarked envelope to each of them and send them out of the room in opposite
directions. Do not inform the “suspects” about what will happen when they return to the class; this
would give the guilty person time to prepare himself, nor should they talk to each other at any time.
They are to knock on the door when ready to return.
5. While the suspects are out of the room, tell the class the circumstances of the crime. Explain their
task and the scoring procedure they will use. You will need to assign to students three roles:
. One or more students to note the suspect’s verbal response.
. One or more students to note the suspect’s reaction time.
. Two or more students to note significant signs of expressive behavior accompanying each
verbal response (see Expressive Behavior Encoding Guide and tally table). Does the suspect
stutter, answer in an especially low or loud voice, clear throat, cough, sigh, etc.?