In real life, individuals are faced with more than one perceptual event on which they have to make distinct decisions. In a series of papers with Dov Sagi we have shown that for a range of such multistimulus environments, decision behavior departs from optimality in the sense that subjects do not set their decision criteria in accordance with the requirements of each individual event (Figure 1). This behavior is explained in terms of a unified internal representation of the multistimulus environment, presumably resulting from the relaxation of attention to the critical dimension associated with each stimulus. Exceptions are observed for cross-modal (audiovisual) stimulations and for stimuli showing sensory interference. We proposed that decision behavior and the selection process required to segment sensory objects are intimately related. Response criterion interaction may account for phenomena such as extinction and may be the substrate of a number of contextual effects.


Figure 1. (a) Standard Signal Detection Theory framework for detection of one (left) and two unequally salient events yielding equal (top) or unequal internal noises. (b) The equivalent representation for the detection of two events under the unique internal representation (uir) for equal (top) and unequal related internal noises. (c) Predicted criteria and criteria ratio as a function of dí and dí ratio under SDT and uir, respectively.

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