Dependence of the filled-space illusion on the location of a distractor
Author | Affiliation | |
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Lietuvos sveikatos mokslų universitetas | ||
Date |
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2020-07-11 |
no. 956
The aim of present study was the further development of a quantitative model of the filled-space illusion and the study of its ability to account for the effects caused by stimuli containing various contextual fillers. Materials and methods In the three series of experiments of the present study, we investigated the illusory effect as a function of distance between the distracting dot and lateral terminator of the reference spatial interval of the three-dot stimulus. The stimuli used in the experiments consisted of three horizontally arranged dots (diameter, 1 min of arc; luminance, 75 cd/m2), which were considered as terminators (tR, tC, and tT, Fig. 1) specifying the ends of the reference and test stimulus intervals; the length of the reference interval, R was fixed at 60 min of arc. Subjects adjusted the length of the empty test interval to that of the reference, and the matching errors were considered as the illusion magnitude. It was demonstrated that the model calculations properly predict all the illusion magnitude changes for stimuli with a single distracting dot placed both within and outside the interval as well as for stimulus with two distractors arranged symmetrically relative to the lateral terminator. Fig. 1: Examples of stimuli used in experiments. The three‑dot stimuli are comprised of short vertical ticks tR, tC, and tT. These vertical ticks serve as distracting line‑segments that are placed either outside (A) or inside (B and C) of the reference interval. R and T, the length of the reference and test interval, respectively; d, the length of the distractor; γ, the coefficient determining the position of gaze fixation X. Dotted lines, the dimensions were not part of the actual display. In experiments, white stimuli (luminance of all the ticks and lines, 20 cd/m2) were presented against ...[...].