The deception literature has predominantly focused on detection of guilty individuals using electrodermal measures. Little research has examined other psychophysiological measures or the mechanisms underlying deception. Therefore, the present study examined pupillary responses in a differentiation-of-deception paradigm. Twenty-four undergraduate participants answered the same questions twice, once truthfully and once deceptively, while pupillary responses were recorded. Questions were based on recently learned (episodic) information from scenarios or on general (semantic) knowledge from long-term memory. Task-evoked pupil dilation was significantly greater when participants confabulated responses than when they told the truth for both episodic and semantic memory questions. Previous research has demonstrated that pupil size increases with increased cognitive processing load. The present study suggested that generating deceptive recall was associated with increased pupil size and required greater cognitive processing than truthful recall.

Task-evoked pupillary responses were recorded during a visual backward masking task as an index of resource allocation. Increased pupillary dilation indicates increased allocation of processing resources to the task. Consistent with numerous studies, detection accuracy increased with longer interstimulus intervals and approximated no-mask accuracy in the 300-ms condition. Pupillary dilation responses were significantly greater during task performance (cognitive load) than during a passive stimulus viewing condition (no-load) and were significantly greater in the 300-ms condition than the no-mask condition. Consistent with models of early visual information processing, the results suggest that the mask demanded extra processing resources when it followed the target by more than 100 ms. Pupillography methods may be useful in evaluating the contribution and timing of resource-demanding processes during early visual information processing.