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

Decision Commitment with Incomplete Evidence

Juan R. Castiñeiras de Saa¹, Mafalda Valente¹, Ulysses Tsai¹, Alfonso Renart¹; ¹Champalimaud Foundation

Presenter: Juan R. Castiñeiras de Saa

How is commitment achieved in perceptual decisions under incomplete evidence? Standard models relying on bounded accumulation of evidence assume a readout based on the sign of the accumulator at stimulus termination, but this has not been properly validated. We aimed to resolve this by adapting an established rat auditory lateralization task, imposing varied maximum sound durations (SDmax). When SDmax was shorter than typical reaction times, accuracy decreased, but remained surprisingly high even for very brief stimuli (e.g. 15ms). Computational modeling, using an adapted DDM framework incorporating both stimulus-dependent and stimulus-independent decision processes, explored how choices are determined post-offset. Models assuming the aforementioned standard readout failed to capture the data. Instead, behavior was best explained by assuming evidence integration continues after offset (approximated by exponential decay of the neural activity providing the sensory input), but crucially, if the decision bound is not reached during this period, the subsequent choice is random. Overall, this work quantifies decision-making under temporal constraints, indicating that bound-crossing is a fundamental requirement to reliably convert integrated sensory evidence into a specific behavioral choice.

Topic Area: Reward, Value & Social Decision Making

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