LAUSR

As one of the commonly used folk psychological concepts, self‐deception has been intensively discussed yet is short of solid ground from cognitive neuroscience. Self‐deception is a biased cognitive process of information to obtain or maintain a false belief that could be both self‐enhancing or self‐diminishing. Study 1 (N = 152) captured self‐deception by adopting a modified numerical discrimination task that provided cheating opportunities, quantifying errors in predicting future performance (via item‐response theory model), and measuring the belief of how good they are at solving the task (i.e., self‐efficacy belief). By examining whether self‐efficacy belief is based upon actual ability (true belief) or prediction errors (false belief), Study 1 showed that self‐deception occurred in the effortless (easier access to answer cues) rather than effortful (harder access to answer cues) cheating opportunity conditions, suggesting high ambiguity in attributions facilitates self‐deception. Studies 2 and 3 probed the neural source of self‐deception, linking self‐deception with the metacognitive process. Both studies replicated behavioral results from Study 1. Study 2 (ERP study; N = 55) found that the amplitude of frontal slow wave significantly differed between participants with positive/self‐enhancing and negative/self‐diminishing self‐deceiving tendencies in incorrect predictions while remaining similar in correct predictions. Study 3 (functional magnetic resonance imaging study; N = 33) identified self‐deceiving associated activity in the anterior medial prefrontal cortex and showed that effortless cheating context increased cheating behaviors that further facilitated self‐deception. Our findings suggest self‐deception is a false belief associated with a distorted metacognitive mental process that requires ambiguity in attributions of behaviors.