page_title: Illusory contours
section_title: Related visual phenomena
hierarchical_section_title: Illusory contours / Related visual phenomena
caption_attribution_description: English: An example of neon color spreading.
context_page_description: Illusory contours or subjective contours are visual illusions that evoke the perception of an edge without a luminance or color change across that edge. Illusory brightness and depth ordering frequently accompany illusory contours. Friedrich Schumann is often credited with the discovery of illusory contours around the beginning of the twentieth century, however illusory contours are present in art dating to the Middle Ages. Gaetano Kanizsa’s 1976 Scientific American paper marks the resurgence of interest in illusory contours for vision scientists.
context_section_description: Visual illusions are useful stimuli for studying the neural basis of perception because they hijack the visual system's innate mechanisms for interpreting the visual world under normal conditions. For example, objects in the natural world are often only partially visible. Illusory contours provide clues for how the visual system constructs surfaces when portions of the surface's edge are not visible.
  The encoding of surfaces is thought to be an indispensable part of visual perception, forming a critical intermediate stage of visual processing between the initial analysis of visual features and the ability to recognize complex stimuli like faces and scenes.
  Amodal perception
  Autostereogram
  Filling-in
  Gestalt psychology
  Negative space
  Reification
caption: Neon color spreading: the cyan circle's contours are illusory