Spatial constraints on the voluntary control of attention across visual space.

Abstract

Two experiments employing a modified version of the Posner, Snyder and Davidson (1980, Exp. 5) luminance detection paradigm investigated the extent to which attention can be voluntarily allocated across the visual field during a single fixation. Results from Experiment 1 indicated that subjects were constrained to voluntarily attending to a single primary locus (as opposed to two noncontiguous loci) in space. These findings were replicated in Experiment 2 in which eye movements were monitored. These results replicate those found by Posner et al. and conflict with similar studies using letter localization (Egly and Homa, 1984, Exp. 3) and letter identification (Shaw and Shaw, 1977) tasks. Possible reasons for this apparent discrepancy in the literature are suggested.