Abstract

In this journal club, we will discuss two recent studies that aim to clarify how the brain computes decision confidence alongside decision content. We will first discuss recent work from Boundy-Singer et al. (2025) that suggests that confidence judgements reflect a subject’s estimate of decision reliability. They corroborate this proposal with neural recording data from two monkeys performing a simple orientation discrimination task, which demonstrated that both decision content and decision confidence judgements are decodable from V1 but decision confidence requires additional nonlinearities to be decoded successfully from V1 activity, as is expected from a two-stage process model of decision confidence.

In a related study, Vivar-Lazo and Fetsch (2025) examined the temporal aspects of choice and confidence computations. They trained two monkeys in a very similar task to report both their perceptual decision and their confidence with a single eye movement, while neural activity was recorded in lateral intraparietal cortex (LIP), a region involved in attention and planning of saccades. Using two evidence accumulation models, they investigated whether confidence is determined only after choice commitment (the serial model) or during decision formation (the parallel model). While quantitative behavioural model comparison was inconclusive, with both models describing choices and reaction times well, only the parallel model was able to account for the observed increase of confidence with stimulus strength in error trials. The activity of LIP neurons was also more consistent with the parallel evidence accumulation model.

Taken together, these studies show promising evidence that decision confidence is represented concurrently with decision content, even in early sensory areas, and suggest that such representations could be transformed for direct access in downstream areas.

References:

Boundy-Singer, Z. M., Ziemba, C. M., & Goris, R. L. (2025). Sensory population activity reveals downstream confidence computations in the primate visual system. Proceedings of the National Academy of Sciences, 122(26), e2426441122. https://doi.org/10.1073/pnas.2426441122

Vivar-Lazo, M., & Fetsch, C. R. (2025). Neural basis of concurrent deliberation toward a choice and confidence judgment. Nature neuroscience, 1-12. https://doi.org/10.1038/s41593-025-02116-9