Modeling Accuracy, Response Time, and Bias in Continuous Orientation Judgments

Abstract

Despite the prevalence of real-world and laboratory tasks where people select among many options, cognitive models have traditionally focused on choices among small sets of alternatives. This has resulted in theoretical and empirical gaps in understanding the decision processes that go into selections among many alternatives or responses that fall along a continuum. This paper addresses these issues by modeling decisions in a perceptual study where participants produce continuous orientation judgments. The experiments showed that manipulations of stimulus difficulty and time pressure have parallel effects to binary choice, with greater stimulus difficulty yielding slower and less accurate responses and time pressure resulting in faster responses at the expense of accuracy. These effects were well accounted for by the circular diffusion model developed by Smith (2016), with drift magnitude parameters shifting with difficulty and threshold parameters shifting with time pressure. However, a manipulation of bias using a predecision cue resulted in bimodal distributions of responses that cannot be explained by the model in its original formulation. To account for this result, I developed a theory of bias based on split attention and racing 2D diffusion processes. This model suggests that responses are determined by both cue-driven and stimulus-driven evidence accumulation processes, such that the winning process determines responses and response times (RTs). As a result, it predicts critical features of responses and response times in the conditions with predecision cues, including bimodal distributions of responses and the longer RTs observed when there was a discrepancy between cue and stimulus orientations.