Abstract
Redundancy gain refers to more efficient target processing when two targets are present than when one target is present. This efficiency often manifests as shorter response times (RT). Previous work has sometimes indicated a redundancy gain in target categorization tasks, and sometimes indicated no redundancy gain for such tasks. The purpose of the current study was to determine under what conditions categorical processing can benefit from redundant targets, and under what conditions it will not benefit. Participants performed a go/no-go task in which they responded only to digits rotated 45° to the left, but not to digits rotated to the right or to letters at either orientation. Each trial contained either a single stimulus or 2 redundant stimuli subtending 1° visual angle and separated by 6° visual angle. In separate blocks, stimuli were arranged unilaterally 3° to the left or right of center, along the vertical meridian, or bilaterally 3° above or below center. Accuracy was near ceiling and did not significantly differ between single and redundant targets. When stimuli were presented for 1500 ms (Experiment 1), the only significant difference between single and redundant target conditions occurred when stimuli were presented along the vertical meridian. This difference indicated a redundancy loss (single RT = 504 ms, redundant RT = 564 ms, p = .001). By contrast, when stimuli were presented for 100 ms (Experiment 2), the redundancy loss for vertical meridian displays remained (single RT = 444 ms, redundant RT = 485 ms, p < .001), but a significant redundancy gain also occurred for bilateral displays in the upper visual field (single RT = 465 ms, redundant RT = 431 ms, p = .002). The results indicate that interhemispheric processing may be necessary to create redundancy gain in categorization tasks, and that longer display durations may mask redundancy gain.
Meeting abstract presented at VSS 2017