Time and making perceptual decisions J Fiser1, M Popovic2, R M Haefner3, M Lengyel4 |
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1Department of Cognitive Science, Central European University, Hungary |
| In models of perceptual decision making within the classical signal processing framework (e.g. integration-to-bound), time is used to accumulate evidence. In probabilistic, sampling-based frameworks, time is necessary to collect samples from subjective posterior distributions for the decision. Which role is dominant during perceptual decisions? We have analytically derived the progression of the error and subjective uncertainty in time for these two models of decision making, and found that they show a very differently evolving pattern of the correlation between subjects’ error and their subjective uncertainty. Under sampling, after a brief initial period, the correlation always increases monotonically to an asymptote with this increase continuing long after the error itself has reached its asymptote. In contrast, integration-to-bound shows increasing or decreasing changes in correlation depending on the posterior’s kurtosis, and with additive behavioral noise, the correlation decreases. We conducted a decision making study where subjects had to perform time-limited orientation matching and report their uncertainty about their decisions, and found that the results confirmed both predictions of the sampling-based model. Thus, under typical conditions, time in decision making is mostly used for assessing what we really know and not for gathering more information. |
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