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.
[Nystagmus versus sensation as cause of optic rotatory illusion].
Explore the source record for details and available documents.
[The coloration of optical delusions, illusions].
Explore the source record for details and available documents.
Geometrical factors in illusions of direction.
Explore the source record for details and available documents.
The effect of hue and brightness on the size-illusion of concentric circles.
Explore the source record for details and available documents.
[Phase phenomena in analyzers. II. Analysis of the optical rotatory illusion].
Explore the source record for details and available documents.
The Leaning Tower of Pisa effect: an illusion mediated by colour, brightness, and motion.
We report a novel, easily observed, and extraordinarily striking optical illusion mediated by interactions of colour, brightness, form, and motion perception--the Leaning Tower of Pisa (LTOP) illusion. Under some circumstances, the perception of orientation of coloured forms is radically altered by rotary movement. We demonstrate that this kinetic effect--easily reproduced with a common record turntable--is optimised by particular colour and brightness differences between foreground and background with an illusory tilt of 8 degrees and more. The described illusions can be easily studied at home by downloading the colour figures from www.perceptionweb.com/perc1000/ditzinger, printing them on a common colour printer and placing them on a rotating record turntable.
Sex differences in susceptibility to the Poggendorff illusion.
This study presents experimental results indicating that there are sex differences in the susceptibility to a geometric optical illusion. Participants (57 male and 39 female undergraduate students) performed 3 trials on a test involving the Poggendorff illusion. Analysis indicated that the magnitude of the illusion diminished significantly with each trial and that the percent perceived error was significantly larger for women than for men. This finding is consistent with the numerous studies which have indicated better visuospatial abilities for men than for women.
Examining the crossmodal consequences of viewing the Müller-Lyer illusion.
For many years, the Müller-Lyer illusion was studied as a purely "visual" illusion, but like many other optical illusions, the evidence now shows that it also occurs when stimuli are presented tactually. In the present study, we investigated whether the visual perception of the illusion would have any crossmodal consequences for haptic perception. The wings-in and wings-out parts of the Müller-Lyer illusion were placed end-to-end, sharing a central fin. This Brentano version of the illusion was presented visually on a screen in front of the participants, who had to compare the "felt" length of two sticks placed on the back of the screen, one behind either part of the illusion. Our results show that the presentation of the visual illusion modified the felt lengths of the sticks presented directly behind the illusion. In particular, the stick presented on the side of space perceived visually as being shorter (behind the wings-in part of the display) was perceived as longer, and vice versa for the stick mounted behind the space perceived visually as longer (behind the wings-out part of the display). These results highlight the crossmodal consequences of the visual perception of the Müller-Lyer illusion for the haptic perception of line length.
Effect of esthetic illusions on rhinoplasty assessment.
OBJECTIVE: Esthetic assessment in rhinoplasty represents a balance between art and science. The result of surgical maneuvres in creating esthetic illusions has been alluded to, but has never been scientifically reported. This project analyzed the effect of optical illusions in esthetic assessment. METHOD: Eight rhinoplasty case studies were designed using computer imaging. Two hundred and ten judges analyzed the apparent differences in one parameter, such as tip projection, tip rotation, dorsal hump, and nasal size, when a different parameter was altered. RESULTS: This study confirms the validity of nasal esthetic illusions. These results indicate how surgical maneuvres that vary one parameter can create the illusion of a variation in tip projection or tip rotation. CONCLUSIONS: The surgeon can exploit esthetic illusions to provide greater control over rhinoplasty dynamics.
Cognitive controls of attention deployment as determinants of visual illusions.
Explore the source record for details and available documents.
The presence or absence of visual coriolis illusions at various combined angular velocities.
Explore the source record for details and available documents.
Psychophysical determination of visual processing time by comparing depth seen in Pulfrich and Mach-Dvorak illusions.
A practical course for preclinical medical students was developed to illustrate aspects of binocular vision and mechanisms of primary visual transduction. It is based on a graphic analysis of two optical illusions, the Pulfrich and the Mach-Dvorak phenomena. A pendulum swinging in a plane perpendicular to the direction of observation appears to follow an elliptical path when viewed binocularly with a filter in front of one eye (Pulfrich illusion) or with alternating occlusion of the right and left eye above a critical frequency (Mach-Dvorak illusion). The Pulfrich phenomenon permits us to determine the relationship between perceived illusory depth and filter density. Analyzing the Mach-Dvorak phenomenon allows us to determine the dependence of illusory depth on interocular delay. Comparison of both determinations (depth against transmission and depth against time) permits us to establish, without complex calculations, the effect of luminescence on visual processing time. In addition, this course illustrates a general methodological concept mentioned by Popper: students make an unexpected observation, put forward a testable hypothesis, and try to falsify it.
Supplementary report: effect of practice on an illusion.
Explore the source record for details and available documents.
The cause and practical importance of oculogravic illusions.
Explore the source record for details and available documents.
Visual illusions in the interpretation of the radiographic image.
The human body is a complex of tissues of different radiographic densities. Overlapping shadows, differences in background density, subjective contour formation, and the parallax effect often produce a variety of optical illusions that exist only in the "mind's eye" and may be mistaken for significant pathology. Most of these phenomena are produced by the Mach effect, a consequence of the physiological process of lateral inhibition. Subjective contour formation is a "psychophysiological" phenomenon in which complete "structures" appear from minimal outlines. A parallax effect occurs if real structures contribute to the radiographic image. This review discusses the basic physiology involved in image reception and the formation of false images. Clinical consequences of the presence of Mach bands, background density effect, subjective contours, and real or physical phenomena are illustrated.
An investigation of the response mechanism of the size-weight illusions.
Explore the source record for details and available documents.