Article ID: 792
Within-series variations in physiological activities during the concealed information test (CIT) systematically differ depending on knowledgeable and unknowledgeable conditions. This study focused on the quantification of such variations by using first-order difference of items in pre- and post-stimulus physiological measures. For a laboratory CIT data (n=21) including both knowledgeable and unknowledgeable conditions, first-order differences were calculated for skin conductance response (SCR) and pre- and post- stimulus phases of skin conductance level (SCL) and normalized pulse volume (NPV). Two types of effect size were calculated for each question item as a summary statistics: The first type based on a difference between a given item and other items and the other based on a difference between items presented before a given item and those presented afterward. Detection efficiencies of these measures were estimated using areas under the receiver operating characteristic curves (AUC) contrasting recognized item and non-recognized items. AUC indicated that first order differences produced significant recognized versus non-recognized differentiation, but their efficiencies were generally somewhat lower than a more conventional approach using raw values. Similar tendencies were replicated in another dataset. These results suggest that within series variations of pre- and post-stimulus physiological activities provide additional information for examining the physiological differences in the CIT.
