THE HUMAN BRAIN REPRESENTS CHOICES ABSTRACTLY INDEPENDENT OF TASK AND MOTOR CONTEXTS

Perceptual decisions are often framed in terms of the actions used to report a choice. Accordingly, most studies rely on tasks with fixed choice–response mappings, in which choice and motor response are tightly coupled. Here, we dissociate choice from response using flexible mappings operating on multiple timescales. Participants performed one of two motion-discrimination tasks in which the choice–response mapping was either provided before (pre-) or after (post-) stimulus presentation and switched on a trial-by-trial basis (Experiment 1, N = 33), or was held constant across blocks of trials (Experiment 2, N = 16). Neural activity was recorded with magnetoencephalography (MEG), and multivariate analyses were used to decode task-relevant variables. Across both tasks, we identified neural signals representing the perceptual choice independently of stimulus features and motor responses. The temporal dynamics of these signals were consistent with evidence accumulation, and their magnitude scaled with both accuracy and subjective confidence, consistent with a neural decision variable. Moreover, choice representations were similar across pre- and post-stimulus mapping conditions and were spatially distinct from motor response representations. Together, these results suggest that an abstract choice stage is a general property of human perceptual decision-making, and highlight the importance of disentangling decision and action processes in models of perceptual choice.