Dynamic presentation boosts the Ebbinghaus illusion but eliminates simultaneous contrast and Muller-lyer

1. One case (Professor J. J. Thomson) sees only three colours in the bright spectrum—red, green, and violet. He can distinguish nothing of the nature of pure yellow, like the sensation given him by the sodium flame in the spectrum. There is no definite colour to him at the portion of the spectrum where the normal sighted see pure blue. Reddish-green would describe the orange and yellow regions and greenish-violet the blue. λ 5950 (orange-yellow) is the point which differs most from red and green. There was no shortening of either end of the spectrum. The point of junction of the red and green differed somewhat in repeating the observations because of his great sensitiveness to simultaneous contrast. It was, however, always in the orange or orange-yellow, never in the yellow of the normal sighted. Difference of Hue Perception .—I then tested him with my apparatus for ascertaining the size of different parts of the spectrum which appear monochromatic, and found that he was defective in distinguishing differences of hue. A portion of the spectrum corresponding to the D lines, and isolated by two shutters in the eye-piece of the spectroscope, was first shown. The shutter on the red side was gradually opened until a difference of hue was seen. The monochromatic patch extended from λ 5889 to λ 6052, being exactly half as large again as that of the normal sighted, which occupies the space from λ 5889 to λ 5998. The monochromatic patch the called greenish-yellow. His monochromatic patch in the centre of the green bore exactly the same proportion to mine as in the case of the orange-yellow, being just half as large again.

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Figural and Semantic Factors in Change in the Ebbinghaus Illusion across Four Age Groups of Children

Perceptual and Motor Skills ◽

10.2466/pms.1996.82.1.15 ◽

1996 ◽

Vol 82 (1) ◽

pp. 15-18 ◽

Cited By ~ 17

Author(s):

Lucia Zanuttini

Keyword(s):

Age Groups ◽

Older Children ◽

Ebbinghaus Illusion ◽

Taxonomic Organization

Changes in the Ebbinghaus illusion across age groups have been studied with 80 children ( ns = 20) from 4 to 8 yr. old. The distortion, whose magnitude increases across age groups, depends on active cognitive comparative processes. In fact, if some cues make the geometrically identical inducing elements semantically different from the central one, the illusion decreases as older children develop conceptual categories. Across ages 4 to 8 years not only the magnitude of the illusion changes but also the interfering role of the taxonomic organization.

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Visual Illusions Affect Motor Performance, But not Learning in Highly Skilled Shooters

Journal of Motor Learning and Development ◽

10.1123/jmld.2017-0011 ◽

2018 ◽

Vol 6 (2) ◽

pp. 220-233 ◽

Cited By ~ 3

Author(s):

Moslem Bahmani ◽

Jed A. Diekfuss ◽

Robabeh Rostami ◽

Nasim Ataee ◽

Farhad Ghadiri

Keyword(s):

Self Efficacy ◽

Retention Test ◽

Motor Performance ◽

Visual Illusions ◽

Limited Information ◽

Ebbinghaus Illusion ◽

Optimal Theory ◽

Highly Skilled ◽

Stages Of Learning

Enhanced expectancies are an important component of OPTIMAL theory and are thought to contribute to motor performance and learning. There is limited information, however, on the generalizability of OPTIMAL theory to highly skilled individuals. The purpose of this study was to examine the effects of visual illusions, specifically an Ebbinghaus illusion, on the performance and learning of an aiming task using highly skilled 10-m rifle and pistol shooters. Two groups of shooters with international experience were recruited and practiced with perceived larger and smaller targets. Our results indicated that participants who perceived the target larger reported higher self-efficacy immediately after practice. In addition, these participants had higher shooting performance during practice. Our retention test (24 hours later), however, did not produce differences in self-efficacy or shooting performance. Our data suggests that visual illusions are beneficial for motor performance in highly skilled shooters, but may not affect learning in those who are in the latter stages of learning. Further studies should continue examining the role of visual illusions for enhancing expectancies in highly skilled and experienced performers.

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Why some size illusions affect grip aperture

10.1101/866640 ◽

2019 ◽

Author(s):

Jeroen B.J. Smeets ◽

Erik Kleijn ◽

Marlijn van der Meijden ◽

Eli Brenner

Keyword(s):

Extensive Literature ◽

Object Size ◽

Ebbinghaus Illusion ◽

Grip Aperture ◽

Size Information

AbstractThere is an extensive literature debating whether perceived size is used to guide grasping. A possible reason for not using judged size is that using judged positions might lead to more precise movements. As this argument does not hold for small objects, and all studies showing an effect of the Ebbinghaus illusion on grasping used small objects, we hypothesized that size information is used for small objects but not for large ones. Using a modified diagonal illusion, we obtained an effect of about 10% on perceptual judgements, without an effect on grasping, irrespective of object size. We therefore reject our precision hypothesis. We discuss the results in the framework of grasping as moving digits to positions on an object. We conclude that the reported disagreement on the effect of illusions is because the Ebbinghaus illusion not only affects size, but –unlike most size illusions– also affects perceived positions.

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