Computational underpinnings of cognitive effortful performance in short timescales

Despite recent advancements, the mechanisms underlying the decline in cognitive effort during task performance remain unclear. In four experiments (total N ≈ 200), participants engaged in a sustained attention task comprising four blocks of 50 or 200 trials presented in a randomized order. We found that performance declined over both extremely brief and longer bouts of performance, as evidenced by a reduction in correct responses per second. Computational modeling revealed that this decline is driven by a decreasing allocation of cognitive resources to the task. These findings align with theoretical accounts positing that reduced cognitive performance in the short term reflects adjustments in resource allocation, rather than change in response policy, or fatigue - the reduced capacity to perform a task.