Deception and nondeception in guilty knowledge and guilty actions polygraph tests

Two polygraph tests, the Guilty Knowledge Test (GKT) and the Guilty Actions Test (GAT), were compared in a laboratory setting. Men (N = 120) who committed or witnessed a mock crime were required to answer ''no,'' to repeat items, or to remain silent in response to items on the GKT or the GAT. A monetary reward was promised for appearing innocent on the test. An interaction with scores based on skin resistance responses showed that innocent witnesses tested on the GKT and guilty participants tested with either the GKT or the GAT scored more in the guilt direction than did innocent witnesses tested on the GAT. Furthermore, participants who were required to say ''no'' were more reactive to key items than were participants in the silent group.