Marieke van Vugt - Following perceptual decision making in the brain

Many perceptual decision making models posit that participants accumulate noisy evidence over time to improve the accuracy of their decisions, and that in free response tasks, participants respond when the accumulated evidence reaches a decision threshold. Research on the neural correlates of these models' components focuses primarily on evidence accumulation. Far less attention has been paid to the neural correlates of decision thresholds, reflecting the final commitment to a decision. We describe a model of bistable neural activity that implements a decision threshold, and we argue that human lateralized readiness potentials (LRPs) reflect its dynamics. These dynamics are predicted to depend strongly on strategic response biasing, but also to preserve signatures of a drift-diffusion process of evidence accumulation. We show that as the model predicts, LRP amplitudes and growth rates correlate with individual differences in behaviorally-estimated prior beliefs, decision thresholds and and evidence accumulation rates.