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Poster Session A: Tuesday, August 12, 1:30 – 4:30 pm, de Brug & E‑Hall

Perceptual Choices and Confidence Judgements can be Modelled as a Single Accumulation Process

John Grogan, Luc Vermeylen, Sarah-Luoise Mannion, Cameron McCabe, Daria Monakhovych, Kobe Desender¹; , ¹KU Leuven

Presenter: Kobe Desender

Evidence accumulation can continue after a choice is made to incorporate new evidence and inform subjective confidence ratings, but we do not know how this post-choice evidence accumulation process differs from the one that informed the initial choice. Existing models disagree regarding whether the post-decision process is a continuation of the initial choice process or reflects a distinct one. In addition, current models disagree on the question of whether post-choice accumulation processes are subject to time-based or boundary-based stopping rules. We implemented these alternative mechanisms across four classes of models and fit them to human data from a task with a speed/accuracy trade-off applied only to the post-decision confidence rating stage, via a deadline. Speed-pressure decreased confidence-RT, certainty, metacognitive accuracy, and changes-of-mind (CoM). The four classes of models were able to fit the data well, but Boundary-Based Stopping Rules fit the data better than the Time-Based Stopping Rules, as the latter were unable to replicate the pattern of decreasing certainty for slower confidence-RTs. However, the behavioural modelling did not conclusively favour one Boundary model over the other. We therefore compared the evolving Decision Variable with a neural marker of evidence accumulation, the Centro-Parietal Positivity (CPP), to further distinguish these two similar models. The Shared-process Boundary-based model was able to replicate qualitative effects of Certainty and CoM on the CPP, while the Distinct-Boundary model could not. We suggest that post-decision evidence accumulation is boundary-based rather than time-based, and shares information with the initial-decision process rather than being a distinct accumulation mechanism.

Topic Area: Reward, Value & Social Decision Making

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