Background

Two studies were conducted employing both innocent and guilty Ss. the guilty condition was established by having Ss play the role of an enemy espionage agent (courier). Innocent and guilty Ss were separately tested in groups of six or seven Ss. Both relevant-irrelevant (RI) and peak of tension (PT) methods were employed. GSR response to each question was separately recorded for each S. In addition, a composite GSR was also derived from all the Ss in each group. In the first study, separate subgroups were given differential feedback of information regarding the polygraph’s effectiveness during a preliminary phase of the interrogation. Results indicated that those Ss receiving information that the polygraph was effective in detecting their lies were detected more readily during the subsequent actual interrogation than were those Ss receiving information that the polygraph was ineffective. In the second study, no differential treatment of innocent and guilty Ss was included in the design in order to provide a clearer interpretation of the effectiveness of the courier paradigm itself. The design was also modified to allow a more adequate comparison of RI and PT methods of interrogation. In addition, information was sought relative to the question of whether a S can be detected when he is informed that his responses are not being evaluated. Results of the second study confirmed the findings of the previous experiment relative to the effectiveness of both the courier paradigm and the group GSR.