Does Lying Require More or Less Working Memory and What Does it Mean for the Legal System?

Abstract

This study uses subjects’ electroencephalogram (EEG) and behavior to test an assumption underlying the Federal Rules of Evidence (FRE), the rules that determine what evidence juries hear, and an assumption in most cognitive models of lie generation. Although the FRE are intended to promote accuracy, they are premised on untested psychological assumptions. One example of such an untested assumption is an exception to the ban against hearsay, the requirement that the person who actually observed the event must testify under oath. The Present Sense Impression admits hearsay testimony about substantially contemporaneously viewed events based on the assumption that people cannot lie about something they are currently viewing. Here we used two behavioral paradigms and EEG recordings to assess the validity of the legal assumption that lying about something you are viewing is more difficult and the assumption of a majority of lie generation theories that lying requires the generation and maintenance of multiple representations of a to-be-lied-about stimulus. Our measurements of brain activity suggest that for simple stimuli individuals hold less information in visual working memory when lying compared to truth telling, possibly by dropping the truthful representation from visual working memory. With more complex stimuli, however, individuals did not appear to switch cognitive strategies suggesting that either this switch isn’t possible or requires additional time in more complex settings. Our results suggest that the generation and maintenance of multiple representations of a to-be-lied about stimulus is not an absolute prerequisite to lie generation, but likely occurs in all but the simplest of settings. Similarly, our results suggest that the assumptions of the PSI are accurate in simple situations and for extremely short delays, but that the rule should be limited to situations involving only true contemporaneity. Thus, scientifically testing the assumptions that our legal system is based on can benefit both the law and the application of vision science to our lives.