Selective attention and stimulus integration have distinct influences on the temporal dynamics of perceptual decision-making

Responding appropriately to incoming sensory information is crucial for adaptive behaviour. In most real-world contexts, multiple sources of information are simultaneously available, and must be prioritised or combined in the service of adaptive decisions. Here we implemented a decision-making paradigm with the goal of characterizing the computational dynamics of perceptual decisions requiring either selection or integration of distinct sensory information. In late 2019, participants viewed displays in which a single patch of moving dots was presented in isolation (baseline), or where two patches overlapped at the same spatial location. In the overlapping displays, participants were cued to judge the direction of just one of the two dot-patches (selection) or the average direction of both patches (integration). In all tasks participants made speeded judgements indicating whether the task-relevant motion was toward the left or right of vertical, and the angular offset of the task-relevant motion was varied across trials. Relative to the baseline task, non-decision times were longer in the selection and integration tasks, suggesting they may require prolonged or supplementary processing stages. Drift rates were lower, suggesting a reduced signal-to-noise ratio, in tasks involving selection and integration. Our findings highlight the temporal dynamics of perceptual decision-making with multiple concurrent stimuli.