The present
study describes and evaluates a new method for detecting lies. The method
assesses Autonomic Nervous System (ANS) activation based on changes in Peripheral
Arterial Tone (PAT) at the fingertip. In two experimental studies participants had
the opportunity to win monetary prizes if they succeeded in lying in target questions
presented by a computer without being detected. In Experiment 1 participants
were asked to indicate the names of their relatives and friends as well as
their own name, and in Experiment 2 they were asked questions about past
behaviors. Significant enhanced arterial vasoconstriction, indicating autonomic
arousal, was evident post lie in comparison to truth responses. The results
showed that for 83% of the participants in Experiment 1 and for 81% in
Experiment 2, the differences between lies and truthful responses were detected
using the current technique. In both studies the PAT was found to be more
sensitive than an index of arousal measured through the same device (Heart
Rate).
The findings of
the study imply that the PAT should be considered as a member in the
"family" of measures employed in modern polygraphs. It may also serve
to complement the current polygraphic techniques in more limited settings where
there are time constraints, such as in mass screening facilities.
