Abstract
AbstractBackgroundNeuroimaging and lesion studies suggest that the dorsolateral prefrontal and posterior parietal cortices mediate visual metacognitive awareness. The causal evidence provided by non-invasive brain stimulation, however, is inconsistent.Objective/HypothesisHere we revisit major experiments with an improved methodology and a new Kanizsa figure task trying to determine whether bilateral continuous theta-burst transcranial magnetic stimulation (cTBS) over these regions affects perceptual metacognition. Specifically, we tested whether subjective visibility ratings and/or metacognitive efficiency are lower when cTBS is applied to these two regions in comparison to an active control region.MethodsA within-subjects design including three sessions, at one-week intervals, was implemented. In each session, every participant was administered bilateral cTBS to either prefrontal, control or parietal cortices. Two concurrent tasks were performed: real and illusory figure, using a staircase procedure to stabilize objective performance.ResultsWe found strong null findings for the replicated task, suggesting that cTBS affected neither visibility ratings nor visual metacognition. Nevertheless, we also observed that the implementation of illusory Kanizsa figures disrupted metacognitive ability, specifically when cTBS was applied to prefrontal but not parietal areas.Conclusion(s)This study adds new evidence to the debate regarding the role of the PPN in metacognition: specifically, using rigorous criteria, evidence is adduced to show that the DLPFC cTBS selectively interferes with metacognitive awareness. What is more, a novel method for investigating the role of the PPN in metacognition is presented.
Publisher
Cold Spring Harbor Laboratory