Pupil response as a measure of preparatory control of attention in anticipation of deception

Abstract

Deception is generally considered to be more cognitively demanding than telling the truth, driving research interest in the relationship between deception and cognitive ability. Few studies have explored the preparatory attentional state occurring after the decision to be dishonest is made, but before the content of the question is known to the deceiver. Participants in the current study were given "Truth" or "Lie" prompts several seconds before being asked questions about autobiographical information that they answered according to the prompt. Cue-evoked pupillary responses, or the changes in participants' pupils during the fixation period between the prompt and question presentation, served as an objective physiological measure of this preparatory state of attention. To assess cognitive ability, several tasks assessing working memory capacity and attentional control were also administered to determine their relationship with pupil response. Aligned with results from a former study, it was hypothesized that pupil diameter would be greatest in anticipation of "Lie" trials, that working memory capacity and attentional control would be negatively correlated with the proportion of errors committed and positively correlated with pupil size in the final few seconds of the fixation interval, and that pupil diameter variability across the fixation interval would be positively correlated with the proportion of errors committed. Results showed a general pattern of constriction in pupil diameter in the fixation interval, which opposed results from previous studies, and did not provide support for the main hypotheses. Lie trials where participants committed an error displayed a significant decrease in pupil diameter across the fixation interval relative to accurate lie trials. Possible reasons for general pattern of pupil constriction are given, prompting a retesting of the hypotheses under better experimental conditions. It is still possible that there is a general pattern of pupil dilation in this preparatory period.