Figure 2: Expanded perceptual judgment tasks enable quantification of deliberative reasoning behavior.

(A) The components of an expanded perceptual judgment task. Subjects make inferences about the latent state of the world using multiple pieces of unreliable sensory information (i.e., “are these stimuli drawn from category A or B?”). Stimulus strength influences the internal sensory response, which must be converted into a representation of evidence that bears on the specific inference problem. Stimulus-dependent noise can be introduced at either stage of processing. Normative inference can be achieved by integrating information from multiple stimuli, but this process may be limited by time-dependent factors such as leak or noise in memory.

(B) A rate discrimination task using auditory “clicks”. Behavioral quantification shows that the source of internal noise is dependent on the appearance of stimuli rather than on the passage of time. From Brunton et al. (2013).

(C) An orientation judgment task with high-contrast gratings. Separately quantifying sensory and inferential contributions to choice variability suggests that stimulus-dependent noise arises primarily from cognitive systems. From Drugowitsch et al. (2016).

(D) A contrast judgment task where long (1–8 s) gaps separated each appearance of a hyperplaid stimulus. Minimal influence of time-dependent limitations reveals that evidence integration can make use of a robust memory system. From Waskom and Kiani (2018).