台大心理系

Psychologists have long explored the physiological responses associated with the processes of lying. These included increased sweating, breathing, and heart rate, which together gave us the polygraph that is notorious for its high false alarm rate. Since the 1990’s, there has been a shift of paradigm in the studies of deception towards the use of memory-based tasks using dependent measures such as reaction time and the P300 component in event-related potentials. In this talk, I will briefly go through the history of lie detection studies, from polygraph to the guilty knowledge task (a.k.a. concealed information task), from the perspective of cognitive psychology. I will then discuss some preliminary data from my lab that probes the role of working memory in a lying-naming task, in which participants have to lie with truthful words. In short, we found that when participants have to gather information from working memory to lie, lying is associated with longer RT and is negatively correlated with each participant’s working memory capacity. In EEG, during the preparation stage, we observed a greater negative deflection in the 500-900 ms window near frontal-central sites, coupled with decreased high-beta power (25-30 Hz). The high-beta power drop switched to a low-beta power drop (15-20 Hz) in the same sites right before the execution phase, possibly indicating alerting and anticipation. During the execution stage, there was a more positive deflection during the 200-500 ms time window for old, recognized words (FN400), and during the 300-700 ms window for lies. Together, I argue that although lie detection is practically difficult, there are many indirect ways such as memory-based paradigms that cognitive psychologists and neuroscientists have at their disposal.