Neurophysiological Correlates of the Dunning-Kruger Effect Reveal Contributions of Episodic Memory to Metacognitive Judgments of Illusory Superiority

The Dunning-Kruger Effect is a metacognitive phenomenon of illusory superiority in which individuals who perform poorly on a task believe they performed well, yet individuals who performed very well believe they under-performed. This phenomenon has yet to be directly explored in episodic memory, nor explored for reaction times and physiological correlates. We designed a novel method to elicit the Dunning-Kruger Effect (DKE) via a test of item and source recognition while electroencephalography (EEG) was recorded; throughout the task, participants were asked to estimate the percentile in which they performed compared to others. Results revealed participants in the bottom 25th percentile overestimated their percentile the most, while participants in the top 75th percentile underestimated their percentile, exhibiting the classic DKE. Reaction time measures revealed a condition x group interaction whereby over-estimators responded faster than under-estimators when estimating being in the top percentile and responded slower when estimating being in the bottom percentile. Between-group EEG differences were evident between over-estimators and under-estimators when collapsing across all Dunning-Kruger responses, which revealed FN400-like effects of familiarity supporting differences for over-estimators from 400-600ms, whereas old-new memory ERP effects revealed a late parietal component (LPC) associated with recollection-based processing for under-estimators that was not evident for over-estimators. Findings suggest over- and under-estimators use differing cognitive processes when assessing their performance, such that under-estimators rely on recollection during memory and over-estimators draw upon excess familiarity when over-estimating their performance. Episodic memory thus appears to play a contributory role in metacognitive judgments of illusory superiority in the DKE.