this result has important implications for the evolutionary history of the neural substrate involved in the perception of the ebbinghaus illusion.”“This research comparatively assessed grouping mechanisms of humans (n = 8) and baboons (n = 8) in an illusory task that employs configurations of target and surrounding circles arranged to induce the ebbinghaus (titchener) illusion. Exact matches only
In the Ebbinghaus illusion, a circle surrounded by smaller circles is perceived as larger than an identical one surrounded by larger circles. All authors approved the final version of the manuscript for submission.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.Eymond, C., Seidel Malkinson, T. & Naccache, L. Learning to see the Ebbinghaus illusion in the periphery reveals a top-down stabilization of size perception across the visual field. we reanalysed data from an earlier experiment on grasping in the ebbinghaus illusion in which we showed that maximum grip aperture was unaffected by this size-contrast illusion. Notably, the inducers had a reversed effect in the periphery and increased the perceived size of the black disk. The … these circles were then embedded in three different illusory displays; a classical display of the ebbinghaus-titchener illusion; an illusory contour version of the ebbinghaus-titchener illusion; and the classical display of the delboeuf illusion.
Notably, in Experiment 1 we evaluated peripheral and foveal perception independently (see “Experiment 2, main group, with peripheral-foveal contingencies. You are using a browser version with limited support for CSS. Here, we revealed a pure top-down contribution to the perceptual size difference between periphery and fovea. The PSE was determined by fitting a cumulative Gaussian to the data, as in Experiment 1. we compared the magnitude of a size contrast illusion (ebbinghaus illusion or titchener circles) in children and adults. nevertheless, some have argued that the small effect on grasp implies that there is a single representation of size for both perception and action [5]. our results confirm that grasping is affected by the ebbinghaus illusion and demonstrate that this effect cannot be explained by obstacle avoidance.”“A target circle surrounded by larger ‘inducer’ circles looks smaller, and one surrounded by smaller circles looks larger than they really are.
however, this finding is controversial and led to studies with seemingly contradictory results. A multi-lab replication studyPigeons perceive the Ebbinghaus-Titchener circles as an assimilation illusion.Journal of Experimental Psychology. we attempted to replicate this finding and to test different hypotheses based on a direct influence of the context elements on the trajectories of the fingers which could explain this reversal of the illusion effects. This first result showed therefore for our Ebbinghaus disk an unusual deviation from the peripheral-foveal perceptual size difference, while the isolated disk size perception matched the classic decrease with eccentricity.We then tested the updating of this unusual peripheral percept through successive peripheral-foveal presentations of the Ebbinghaus disk. Pelli, D. G. The VideoToolbox software for visual psychophysics: Transforming numbers into movies. Apparent size was defined as the physical size of the Test disk that should be displayed to be perceived as large as the Standard disk, and was evaluated as a ratio of the Standard size. in Bedell, H. E. & Johnson, C. A. A total of 36 new participants took part in Experiment2: 24 participants (aged 21–50 years, 6 men) in the main group (isolated and Ebbinghaus disks conditions with peripheral-foveal contingencies, see “The experiments were programmed in MATLAB, using the Psychophysics and Eyelink Toolbox extensionsThe stimuli were black disks presented in isolation or as Ebbinghaus disks on a gray background (24.8 cd/mIn Experiment 1, we evaluated the apparent size of a Standard black disk, tested in three possible sizes computed by multiplying a reference surface of a 1.6°-diameter disk by a sizing factor (0.9, or 1, or 1.1; Table In Experiment 1, we used a comparison task to evaluate the apparent size of the Standard disk in two disk type conditions (isolated or Ebbinghaus disk) and at two retinal locations (peripheral or foveal) (Fig. analyses of response behaviors and points of subjective equality demonstrated that only humans misjudged the central target size under the influence of the ebbinghaus illusion, whereas baboons expressed a more veridical perception of target sizes. therefore, size contrast as shown by the ebbinghaus illusion is not a built-in property of the ventral pathway subserving vision for perception but a late development of it, and low sensitivity to the ebbinghaus illusion in autism is not primary to the pathology.
the illusion was experienced less strongly by himba compared with english participants, leading to more accurate size contrast judgments in the himba. instead, studies consistently show similar effects of the illusion on grasping.
to find evidence for these implicit comparisons, a variation of the ebbinghaus illusion was used. cognitive contrast explanations take support from the way the illusion varies with the degree of shape similarity between the test and inducing elements; we show, however, that contour interaction explanations may account for this result too. The Ebbinghaus illusion is a classic example of the influence of a contextual surround on the perceived size of an object. Newsome, L. R. Visual angle and apparent size of objects in peripheral vision. If you have the appropriate software installed, you can download article citation data to the citation manager of your choice.