Structure in the noise: understanding temporal variability in perceptual decision-making

Studies of perceptual decision-making typically present the same stimulus repeatedly over the course of an experimental session but ignore the order of these observations, assuming unrealistic stability of decision strategies over trials. However, even so-called ‘stable’, ‘steady-state’ or ‘expert’ decision-making behavior features significant trial-to-trial variability that is richly structured in time. Structured trial-to-trial variability of different forms can be uncovered using latent variable models such as hidden Markov models and autoregressive models, revealing how unobservable internal states change over time. Capturing such temporal structure can avoid confounds in cognitive models, provide insights into inter- and intra-individual variability, and bridge the gap between neural and cognitive mechanisms of variability in perceptual decision-making.