BAKER, L., GOLDSTEIN, R., and STERN, J. A. Saccadic eye movements in deception. December 1992, Report No. DoDPI92-R-0003. Department of Defense Polygraph Institute, Fort McClellan, AL 36205.
Informal observations suggest that saccadic eye movements which occur during the period beginning when a subject indicates readiness for the next trial and ending at the outset of the following trial may be indicative of subject veracity. The validity of this informal observation was tested by calculating analyses of variance using previously collected data from 10 subjects. Among the measures analyzed were: mean saccade amplitude per trial; total saccade amplitude per trial; and total number of saccades per trial as well as visual fixation frequency; mediation fixation durations in a trial around the mean duration for that trial; and variance of fixation durations in a trial calculated around the mean duration of the entire session. Variables examined included the direction of saccadic movement and subject veracity. While there were sporadic significant differences, it is concluded that there is little support for the hypothesis that post-response saccadic or fixation activity can be used to determine subject veracity. It is emphasized that significant effects indicative of subject veracity were found when subjects were responding to a question, but that this response pattern ceases after the response to the question of interest occurs.
Key-words: eye movements, saccadic, detection of deception, subject veracity, eye dynamics
The relationship between eye movement and deception is a sparsely investigated but potentially fruitful area for Forensic Psychophysiology. This study represents a preliminary investigation into the area. It was designed to examine the predictive value of eye movements occurring between a subject's response to a question and the beginning of the next question during a psychophysiological detection of deception (PDD) examination. The report is a reanalysis of previously collected data, details of which are reported elsewhere. The authors interpret the results of this analysis to indicate that eye movements occurring during the specified period are not indicative of subject veracity. Results of the original report, by the same authors, suggest that eye movements measured in response to a question can be indicative of subject veracity.
This preliminary investigation represents an important step in determining the usefulness of eye movement and a measure of deception. It is important because it has provided direction concerning which eye movement features and sample times are not worthy of further investigation.