High Emotional Arousal Enables Subliminal Detection of Concealed Information

Abstract

The Concealed Information Test (CIT) is an information-detecting technique for criminal investigations. Although it has been shown that emotional arousal plays a specific role in the CIT, the mechanisms by which emotional arousal affects the CIT are unclear. The main purpose of this study was to elucidate the processing pathway for stimuli encoded with emotional arousal in a mock crime before the CIT. In this study, participants viewed emotionally arousing pictures before the mock crime. Participants were assigned randomly to either a high or low emotional arousal group, viewing pictures expected to arouse emotion at a high or low level, respectively. Subsequently, all participants enacted the same mock crime, in which they were instructed to stab a pillow with a sharp-edged tool (e.g., kitchen knife or ice pick) as if to harass a woman lying on a bed. After the antecedent emotional experience, a P300-based CIT was conducted using subliminal and supraliminal presentation methods. The results revealed a significantly greater CIT effect on the P300 event-related potential (ERP) component in the High Arousal group compared with the Low Arousal group, under both subliminal and supraliminal conditions. The detection of concealed information was successful only in the High Arousal group under subliminal conditions, whereas detection was successful regardless of the emotional arousal group under supraliminal conditions. These results provide strong evidence that emotional arousal can increase P300 amplitude during responses to concealed information in the CIT. This suggests that concealed information may be automatically processed via the bottom-up route in the CIT, but only when it is encoded with high emotional arousal.