隠匿情報検査における認識由来の生理反応と質問時の音声変化による生理反応の比較

抄録

 The concealed information test (CIT) is an information detection technique measuring differential responses of the autonomic nervous system caused by the knowledge of crime-related information. The purpose of this study is to compare physiological responses caused by crime-related knowledge with those caused by a questioning voice with a deviant pitch in the CIT and to research whether there is any difference between these responses. Participants were assigned to one of three groups: a “knowledgeable” group, an “unknowledgeable” group, and a “deviant-sound” group in which the unknowledgeable participants received a deviant-sound question of a crime relevant item. Each participant chose one of the two envelopes that manipulate to assign the participant to the predetermined group. The envelopes for the knowledgeable group contained instructions with the role of the thief and the item related to the theft, and the envelopes for the unknowledgeable group and a deviant-sound group contained instructions with the role of the innocent. Participants are asked to hide their roles and undergo the CIT. The knowledgeable group and deviant-sound group showed increased electrodermal activity, low heart rate (HR) and low normalized pulse volume (NPV) for relevant items. In the deviant-sound group, there was no suppression of respiration, and low HR appeared earlier compared to the knowledgeable group. The differential responses on thoracic respiratory speed and HR were consistently observed across question repetitions in the knowledgeable group, while the differential responses on skin conductance response, HR and NPV decreased along with question repetitions in the deviant-sound group. The different patterns of differential physiological responses found in the knowledgeable group and the deviant sound group suggested the possibility of distinguishing these two groups. In particular, the suppression of respiration caused by the crime-relevant item may be characteristic of knowledgeable persons. The practical implications are discussed.