NCJ Number
112833
Journal
Polygraph Volume: 17 Issue: 1 Dated: (March 1988) Pages: 16-20
Date Published
1988
Length
5 pages
Annotation
This study assessed the impact of various subject muscular movements to counter polygraph accuracy in measuring deception and tested the effectiveness of an activity sensor in detecting such movements.
Abstract
Three subjects, a male and two females, each performed 23 physical movements at the instruction of the researcher in the course of a polygraph examination. A Lafayette four-pen amplified polygraph instrument with an activity sensor was used. The activity sensor consists of a 28-inch metal strip placed beneath the front two legs of the subject's chair while plugged into the auxiliary input of the multifunction amplifier of the polygraph. The weight of the subject slightly bends the sensor, and any change in the subject's weight distribution alters the bend in the sensor to produce a continuous tracing that can be compared with the other polygraph tracings to inform the polygrapher if and when a movement has occurred. The subjects' every movement resulted in a change in the tracings in at least one of the three measures being used. Findings indicate that a sophisticated subject could create reactions on the control questions that would be greater than responses to the relevant items. The activity sensor detected 92 percent of the movements, suggesting that it can be effectively used to detect subjects' muscular movements designed to undermine polygraph accuracy. 1 table and 11 references.