Abstract
Introduction: Prior work suggests that global image statistics influence perception of a degraded figure in an image. But how much of the image is actually processed? Method: Each stimulus contained a black figure against white ground. Each figure was composed of 4 rectangles. White square distractors were used to degrade a figure, while black square distractors served as noise. There were 3 conditions — figure presented with: all small square distractors, with all large square distractors, and a third ‘mixed’ condition. In the mixed condition, the figure was presented within an imaginary window (somewhat larger than the figure yet smaller than the image). The inside of this window contained all small square distractors, while the outside contained all large squares. Total distractor area was held constant across conditions. On each trial, a subject's task was to respond whether the figure was displayed in its upright or upside-down orientation. Earlier results showed that performance in the all-small distractor case is much better than in the all-large distractor case because the length of the contours of small distractors is short in comparison to that of the contours of the larger figure. In the new mixed distractor condition, if a subject processes only the part of the image inside the imaginary window, performance should be comparable to that in the all-small distractor condition. Otherwise, performance should be comparable to that in the all-large distractor condition. Results: In the mixed distractor condition, performance of some subjects was comparable to that in the all-small distractor condition, while performance of other subjects was comparable to that in the all-large distractor condition. Conclusion: There appear to be individual differences in perception of degraded figures: some process the entire image, while others process only the portion containing the figure and its immediate ground.