Abstract
In preliminary observations, we found that perceived size of elementary dots, which form a circular arrangement, decreases with the increment of the size of the global circular arrangement. We conducted an experiment to understand how the size of the global circular arrangement and actual size of the dots affect this size illusion. In the experiment, six black dots with an equivalent size (0.4, 0.6, or 0.8 arc degree) formed a circular arrangement on a white background. The diameter of the global circular arrangement was about 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, or 6.0 arc degree. Participants observed those 27 stimuli with 57 cm viewing distance. Each of the 27 stimuli was presented four times in random orders. In each of the trial, a fixation point (+) was presented for 200ms on the center of the white display. Then, one of the 27 stimuli was presented for 1000ms at the center of the display. After each stimulus observation, a horizontal row of black dots with different sizes (0.64, 0.68, 0.72, 0.76, 0.8, 0.84, 0.88, 0.92, and 0.96 arc degree) was presented on the display. Participants selected one of the dots from the row whose size was perceptually equivalent to the size of the elementary dots in the stimulus. Our results showed that the perceived size for the elementary dots linearly increased with the decrement of the diameter of the global circular arrangement. In addition, this illusory effect for the size of elementary dots was exaggerated for the small element size in large circular arrangements. These results suggest that the perceived size of the local elements (dots) is affected by the contrast with the size of the global configuration (circular arrangement).
Meeting abstract presented at VSS 2016