Abstract

This study is an experimental study comparing the psycho-physiological response differences of subjects according to the rapport building in polygraph tests. We randomly assigned 84 adults into a 2(veracity: Truth vs. Lie) x 2(rapport; Rapport building vs. Non-rapport building) between-subject design and measured ESS total scores as psycho-physiological responses. In order to manipulate the veracity conditions, participants in the truthful condition were told to tell their actual scores on several simple tasks but those in the lie condition were asked to tell higher scores than their actual scores. Afterwards all participants were polygraph tested in the order of pre-interview and main examination. The rapport conditions were manipulated by structured pre-interview scripts. As a result, there were significant differences in the examinee's total ESS scores depending on the veracity and rapport conditions. For truth-tellers, the ESS total scores were greater in the positive(+) direction in the rapport building condition than in the non-rapport building condition, indicating a prominent true response in the former condition. For liars, however, the ESS total scores were not significantly greater in the negative(-) direction in the rapport building condition than in the non-rapport building condition. Based on this study's results, we discussed the importance of rapport building in the pre-interview phase of a polygraph test and the need to operationalize verbal and non-verbal rapport building techniques.