Abstract
Visual functions vary with retinal eccentricity. Spatial resolution declines with eccentricity, while motion discrimination is often better in the periphery than in the center. Visual attention usually involves the central field, but this might result from demands for spatial resolution. The present study investigated discriminations of both static and moving patterns under varied attentional demands, with multiple patterns in both central and peripheral fields.
Vision was evaluated simultaneously in central and peripheral fields, using three adjacent monitors, each perpendicular to the visual direction - one central and two peripheral displays, at ±30 deg eccentricity. Stimuli were Gabor patches. Static form perception was measured by orientation discrimination thresholds; and motion perception was measured by temporal thresholds for direction discrimination. Attentional demands were manipulated by varying the number and spacing of simultaneous Gabor patches; and visual performance was studied with three different tasks - using spatial cuing, discrimination of a target among distracters, and odd-ball detection. Thresholds in multi-stimulus conditions were compared with those in single-stimulus baseline conditions.
Multiple static forms were visually competitive - in both central and peripheral fields, and especially in the periphery. Moreover, the central and peripheral fields were competitive, with peripheral form discriminations hindered by central attention. With moving patterns, however, competitive visual interactions were reduced or eliminated, both within and between central and peripheral fields. In the central field, interactions among moving patterns were sometimes even cooperative, mutually facilitative. In general, the visual field is organized by qualitatively different spatial mechanisms for perceiving static forms and motion in the central and peripheral regions.
Supported by: NIH grants R03-EY015558 and P30-EY08126