The effect of cognitive load on nonverbal behavior in the cognitive interview for suspects

Abstract

We investigated whether cognitive load results in changes to nonverbal behavior in the context of interrogation, and whether psychopathic traits affected this relationship. Cognitive load was implemented by using the cognitive interview for suspects (CIS). Onehundred- and-fifty undergraduate students were assigned to one of two conditions: 1) a true event, where they played a game with a confederate, and money went missing from a wallet in the room, or 2) a false-alibi condition, where they read a scenario similar to the true event (in order to create a feasible alibi), and were instructed to steal $10 from the wallet. Blinking, hand gestures, trunk movements, and direct eye gaze were coded at each point in the CIS. Regardless of condition, the increase in cognitive load had the effect of increasing blinking and decreasing hand gestures and direct eye gaze. There were significant interactions between CIS stage and experimental condition for blinks and hand gestures, where people in the false alibi condition had a sharper increase in blinking, and decrease in hand gestures when cognitive load was introduced. Psychopathic traits did not affect the utility of above cues, but change in trunk movements was positively correlated with psychopathy in the false alibi condition.