Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Optical Illusions”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1977

Feature analysers, optical illusions, and figural aftereffects.

Simple displacement models cannot explain some aspects of optical illusions and figural aftereffects. The orientation-detector interaction model proposed by Blakemore and others is more suitable to explain many aspects of the Zöllner illusion, positive and negative illusions, the effect of gap between the inducing and test lines, and the anisotropy of illusions. If we hypothesize size detectors whose tuning width and distribution steps are proportional to logarithmic size, interactions between them explain well the fact that the Delboeuf illusion and figural aftereffects of circles are determined by the size of the inducing to test circle, not by the absolute distance between the contours of these circles.

Figural Aftereffect↗
PubMed1992

Optical illusions in clinical dermatology: the Mach band phenomenon and afterimages.

A survey of dermatologists was conducted to determine whether the perceptions of afterimages and Mach bands impacted on clinical dermatology practice. 26.5% (13/49) of respondents indicated that they perceived one or both of these optical illusions. No false-positive potassium hydroxide interpretations of skin scrapings for hyphae were reported due to perceived afterimages, and no skin biopsies were reportedly performed as a result of Mach bands.

Adult↗
PubMed1979

[Certain patterns in the formation of optical illusions].

A structural dynamic analysis of productive disorders in visual perception was attempted on the basis of psychological study of 344 patients. These disorders were studied according to the increasing degree of inadequacy (anisomorphia) of pathological images in respect to real stimula. Considering the differences of such phenomena according to the degree of discrepancy of their perceptive characteristics with the traits of real objects, some successively complicated pathological images were examined, including traditional false recognition, illusions and hallucinations, as well as interlapping intermediate structures. Some pathogenetical mechanisms in the formations of visual illusions are suggested. Clinico-psychopathological parallels are made between disorders of visual perception and disease entities.

Dementia↗
PubMed1976

Optical illusion.

Explore the source record for details and available documents.

Adolescent↗
PubMed1978

Another optical-geometrical illusion.

A new optical-geometrical illusion is described. The parallelism of short rows of dots is affected by some unknown factor, so that the rows appear as pivoting on their middle point. Some explanations of the illusion are considered, but with no success.

Humans↗
PubMed1992

Orbital prosthesis following temporal muscle or forehead flap reconstruction: use of optics and illusions.

Temporalis myocutaneous flap reconstruction of orbital defects may cause difficulty with fabrication of esthetic orbital prostheses because of limited space. Two patient treatments are presented to show the wide variation in defect size that may be encountered after surgical reconstruction. Methods for using optics and illusions to enhance the esthetic result are also presented.

Adult↗
PubMed1992

Geometrical haptic illusions revisited: haptic illusions compared with visual illusions.

Révész (1934) reported that haptic illusions were observed in almost all of the geometrical optical illusion figures. The present study reexamined seven geometrical illusions in both haptic and visual modes. In the Müller-Lyer, Ponzo, and vertical-horizontal figures, haptic illusions equivalent to the visual illusions were observed. In the Oppel-Kundt figure, a haptic illusion similar to the visual one was obtained. In the haptic Delboeuf stimuli, the size illusion of the outer circle occurred, whereas that of the inner circle did not. No haptic illusion was obtained in the Poggendorff figure. In the Zöllner figure, a haptic illusion directionally opposite to the visual one was obtained. These results show that haptic illusions do not occur in all of the geometrical illusion figures. They also suggest that haptic illusions are not necessarily mediated by visualization and that haptic processing of the figures often occurs in a manner different from vision.

Adult↗
PubMed1977

Pseudofracture of the dens: Mach bands.

Mach bands are an optical phenomenon in which dark and light lines appear at the borders of structures of different radiodensity on radiographs. In most instances they do not cause a diagnostic dilemma. However, in a patient who has sustained trauma to the cervical spine, the commonly occuring negative Mach band across the base of the dens may be mistaken for a fracture. Failure to recognize this optical illusion may result in unnecessary treatment by skeletal traction. The production of Mach bands, methods of proving their illusory nature, and several illustrative cases are presented.

Adult↗
PubMed1979

Apparent movements induced by stroboscopic illumination of stabilized images.

Stroboscopic illumination of stabilized images causes habituation effects and illusory phenomena which, at low stimulation frequencies, show up as brighter patches. When a line is used as a stimulus, these patches are observed as brighter spots in the line surrounded by dimmer patches in the background. These locally brighter parts function as sources from which brightness spreads in the direction of the line at light-on and as sinks to which the brightness retracts again after light-off. This spread and retraction of the brightness induces the perception of movements. Higher stimulation frequencies or a diminished stimulus-background contrast enables the brightness to spread also in the direction perpendicular to the line contour, i.e., into the background. Again a perception of movement is induced, local displacements of a part of the field are observed as a result of the brightness spread. Tiny pinpoints of light, the smallest foveal perceptive elements, visible in lines narrower than 10 min arc (Gerrits, 1978), are also observed when these lines are illuminated with stroboscopic light. These tiny elements do not spread their brightnesses and so also no movement is induced. The results are discussed in relation to the properties of the perceptive elements and the cells activating them (habituation, barriers, filling-in).

Afterimage↗