Abstract
Precious studies revealed that visual attention affected detection and discrimination sensitivities of most visual functions. It has not been fully investigated, however, whether depth discrimination is affected by visual attention. In the present study we measured reduction in sensitivity of depth discrimination for the stimuli presented in the peripheral visual field while the observer was engaged in a central attention task. The stimulus consisted of double rings with four possible gaps each, presented in the central visual field for 1000ms, and two pairs of squares, presented in the right and the left visual field, respectively, at eccentricity of 5, 10, 20 or 30 deg in the periphery for 500ms. One of two pairs was the target with binocular disparity between two component squares and the other was the reference with no binocular disparity. The observer detected the gaps of the rings and, at the same time, responded which pair was the target in the double-task condition (DC). The observer simply detected the target with no central attention task in the single-task condition (SC). The results showed that depth discrimination threshold was significantly higher in the DC than those in the SC, which indicated that the visual attention strongly affects depth discrimination sensitivity. Moreover, it was shown that distance from the observer to the stimulus plane had no effect on the threshold, which means that the central attention area is determined by the visual angle.