Polygraph examiner awareness of crime-relevant information and the guilty knowledge test

A mock-theft experiment was designed to examine the efficiency of the Guilty Knowledge Test when (a) the examiner was aware of some of the crime- relevant items; (b) target items (i.e., items that are significant to participants for reasons other than crime-relevance) were incorporated into the test; (c) the motivation of guilty participants to appear innocent was manipulated. Results indicated that (a) participants yielded weaker responses to relevant items when the examiner was aware of them than when he did not have the knowledge; (b) the inclusion of target items had no overall effect on the responses to the relevant items: (c) within the guilty condition, highly motivated participants were more responsive to the relevant items than less motivated participants, and the inclusion of target items significantly decreased detection accuracy of low motivated participants.