Cite as:
Gorea A, Sagi D, 2003, "Selective attention as the substrate of optimal decision behaviour in environments
with multiple stimuli" Perception 32 ECVP Abstract Supplement

Selective attention as the substrate of optimal decision behaviour in environments
with multiple stimuli

A Gorea, D Sagi

Making a decision is by essence an attentional state. We present a series of experiments originally intended to assess decisional behaviour in environments with multiple stimuli, and that eventually pointed to an intimate link between decision and attention. The experiments show that when subjects have to decide on the occurrence of one out of two concurrent (partial report) or sequential events, their decisional behaviour may depart from optimality (in the signal detection theory sense) in that it reveals the use of a 'common denominator' decision criterion. This 'unique criterion' (UC) is not observed when the two events are (a) within different modalities (an auditory intensity and a visual contrast increment) and (b) within the same modality (both visual or both auditory) but interfere. In the latter case, the occurrence of either of the two events can be more accurately detected by tagging it with the responses in the two interacting mechanisms, thus preserving the two-dimensionality of the stimulating condition. Stimuli invoking responses from independent mechanisms (within the same modality) require only one-dimensional tagging. On this view, the dimensionality of the tagging process matches that of the decision process. An equivalent way to phrase this is to say that the UC observed with non-interfering intramodal stimuli is the consequence of merging the decision axes associated with each of them. Classifying (physically distinct) events by means of keeping track of their characterising dimensions is a basic attentional process. Hence attention is, among others, a process by means of which decision axes (and thus response criteria) associated with each of the two (or more) concurrent or sequential events are kept apart. The merging of the decision axes may be conceptualised as the consequence of the 'relaxation' of attention. In short, the selective aspect of attention appears to apply to the dimensionality of decisions. The present audio - visual data suggest that sound pressure and luminance contrast cannot be merged within a unique dimension, even when these two dimensions do not interfere with each other.

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