Illusory contours.html



"Kanizsa Triangle". These spatially separate fragments give the impression of illusory contours (also known as modal completion) of a triangle

Illusory contours or subjective contours are a form of visual illusion where contours are perceived without a luminance or color change across the contour. Friedrich Schumann discovered illusory contours (Schumann 1900).

The Ehrenstein illusion is of a bright disk.

A classic example of illusory contours is the Kanizsa triangle (Kanizsa 1955). This figure comprises three black pac men approaching each other and three black angles on a white background. But many observers see a white triangle on top of three black disks and an outline triangle. The white triangle appears brighter than the white background and shows a contour even in regions where there is no luminance change in the image.

The Ehrenstein illusion is another common form of illusory contours.

It is thought that early visual cortical regions such as V2 are responsible for forming illusory contours (von der Heydt 1984).

See also

• Amodal perception
• Gestalt psychology
• Reification

References

• Kanizsa, G (1955), "Margini quasi-percettivi in campi con stimolazione omogenea.", Rivista di Psicologia 49 (1): 7–30 
• Schumann, F (1900), "Beitrage zur analyse der gesichtswhrnehmungen. Erste abhandlung. Einige beobachtungen über die zusammenfassung von gesichtseindruken zu einheiten.", Zeitschrift für Psychologie und Physiologie der Sinnesorgane 23: 1-32 
• von der Heydt, R; Peterhans, E; Baumgartner, G (1984), "Illusory contours and cortical neuron responses.", Science 244 (4654): 1260-2, http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=6539501&itool=iconabstr&query_hl=11&itool=pubmed_docsum 

• Yoon Mo Jung and Jackie (Jianhong) Shen (2008), J. Visual Comm. Image Representation, 19(1):42-55, First-order modeling and stability analysis of illusory contours.

External links

• Illusory contours figures Many unpublished drawings (fr)