Abstract: 50 students as volunteers were examined with visual event-relatedpotentials (ERP) to detect whether the subjects knew the team-leader. Theteam-leader's photographs were projected as targets with the probability of0.25 randomly with many photographs of strangers as nontargets with theprobability of 0.75 by a slide projector. The probability of the control nontar-gets were the same as the targets the. The subjects were asked to watch thescreen and press either one of the two buttons (YES or NO) while he sawthe familier or the stranger's photograph. The functions of these two buttonswere the same as thoser to trigger the projector for the next slide and theevoked potential equipment for averaging of the electricity from the scalp. Theamplitude and area of P3 wave from Cz and Pz with targets and nontargetswere calculated and analized by a microcomputer. It was considered as posi-tive if three of the four parameters which included the amplitude and area ofP3 from Cz and Pz with targets larger than those with nontargets. The positive rate was 98% and the false negative was 2%. It was indi-cated that the P3 of ERP could be utilized to find out whether the subjectconfessed truly that he was familier with his team-leader.

Key words: ERP, Photograph, Lie detection