Proceedings of the Annual Meeting of the Cognitive Science Society

A hallmark of optimal decision making is that cues are weighted by their reliability. Previous studies have reportedevidence for reliability weighting in several human perceptual decision-making tasks in which sensory noise was the onlypossible source of errors. Here we use a target detection task to test whether optimality generalizes to situations where stimulusambiguity is an additional source of uncertainty. Target and distractor orientations were drawn from distributions with differentmeans and the level of ambiguity was varied through the amount of overlap between the two distributions. In line with previousstudies, we found clear evidence for sensory reliability-weighting, regardless of the level of ambiguity. However, using a richerset of models than before, we also found that the estimated weights deviated from the optimal ones. Finally, we found no effectof ambiguity level on task efficiency, which suggests that subjects optimally accounted for this source of uncertainty.