The effects of pre-viewing of mock crime scene on detection of deception using P300.

点击翻译按钮获取中文摘要

Japanese field polygraphy is unique in relying on the Guilty Knowledge Test (GKT) for determining guilt. A feature of field GKTs is that the interval between the commission of the crime and the testing is much longer (usually at least a month vs.a few minutes) than in laboratory GKTs. This fading of memory through time suggests that field accuracy is reduced relative to lab accuracy. The present study, with event-related potential(P300) as the dependent variable, was designed to test whether refreshing the memory of laboratory mock crime details just before the administration of the GKT would enhance GKT accuracy. The mock crime involved entering a room, and stealing an item (ring) from one of five desk drawers. The GKT was administered about a month after the mock crime. Just before the GKT, the refresh-memory group (RM) of 10 subjects viewed a video which depicted the room in which they had committed the mock crime about a month ago, while the remaining 10 subjects in the no-RM (NRM) control group viewed a video of the same length that depicted scenes from other parts of the college. GKT accuracy in both groups was high, with the critical-item pictures eliciting greater P300s than the non-critical pictures (p<.001), and the P300 measure identifying 17 of the 20 subjects correctly as guilty. However, GKT accuracy did not differ between the two groups. Future studies will test the hypothesis that to enhance GKT accuracy in the lab, one must not only cognitively refresh subjects' memories, but also motivate them to pay more attention the details of their mock crime.