Light-from-above assumption

from Wikipedia, the free encyclopedia
According to the "light from above" assumption, the left circular area is perceived as convex, while the right area rotated by 180 ° is perceived as concave.

As a "light-from-above" presumption (also: "light-from-above" heuristics , English: light-from-above prior ) is referred to in psychology, the finding that the human being based on experience in dealing with the Environment usually assumes that light comes from above. The consequence of this is that light and shadow patterns are interpreted under the assumption that a single light source shines down from above.

description

When interpreting visual stimuli, the visual system assumes a single light source shining down from above. This assumption corresponds to the human experience with the environment, since the sun and artificial light sources are usually positioned above the human being. A circular, shaded two-dimensional surface, which is brightest in the upper area and darker towards the lower end, is consequently perceived as a convex cusp. If the shading pattern is reversed, however, the surface is interpreted as a concave dent. This perception experience is also evident in more complex patterns such as footprints in the sand.

The “light from above” assumption shows a small tendency to the left. This means that an object is more likely to be perceived as convex when it is brightest in the upper left area and darker towards the lower right area. This tendency to the left seems to be influenced by cultural influences. English speakers read texts from left to right and have a stronger tendency to the left than Hebrew speakers who read from right to left. The handedness of a person does not have a significant impact on the "light-von-up" -Vorannahme.

The assumption is not rigid. It is adapted through experience with the environment. This can happen, for example, when lighter at the top and darker at the bottom of surfaces haptic not as usual convex, but now are concave experience.

Retinal image and gravity

The visual system seems to rely largely on retinal information and only to a small extent on gravity in order to determine what can be identified as "above" or "below" in relation to humans. As a result, when the head is tilted to one side, when an object is perceived as convex or concave, it shifts largely due to the shift in head position and the accompanying altered retinal image.

Web links

Commons : "light-from-above" assumption  - collection of images, videos and audio files
  • Stimuli to demonstrate the "light-from-above" assumption

Individual evidence

  1. ↑ a b Vilayanur S. Ramachandran: Perceiving Shape from Shading . In: Scientific American . tape 259 , no. 2 , 1988, p. 76-83 .
  2. ↑ VS Ramachandran: Perception of shape from shading . In: Nature . tape 331 , no. 6152 , January 1988, ISSN  0028-0836 , p. 163–166 , doi : 10.1038 / 331163a0 ( nature.com [accessed May 10, 2020]).
  3. ↑ a b Wendy J Adams, Erich W Graf, Marc O Ernst: Experience can change the 'light-from-above' prior . In: Nature Neuroscience . tape 7 , no. October 10 , 2004, ISSN  1097-6256 , p. 1057-1058 , doi : 10.1038 / nn1312 ( nature.com [accessed May 10, 2020]).
  4. ^ Marc O. Ernst, Massimiliano Di Luca: Multisensory Perception: From Integration to Remapping . In: Sensory Cue Integration . Oxford University Press, 2011, ISBN 978-0-19-538724-7 , pp. 224–250 , doi : 10.1093 / acprof: oso / 9780195387247.003.0012 ( oxfordscholarship.com [accessed May 10, 2020]).
  5. ↑ Lorin J. Elias, Brent M. Robinson: Lateral biases in assumptions of lighting position . In: Brain and Cognition . tape 59 , no. 3 , December 2005, p. 303-305 , doi : 10.1016 / j.bandc.2004.08.021 ( elsevier.com [accessed May 10, 2020]).
  6. ↑ Pascal Mamassian, Ross Goutcher: Prior knowledge on the illumination position . In: Cognition . tape 81 , no. 1 , August 2001, p. B1 – B9 , doi : 10.1016 / S0010-0277 (01) 00116-0 ( elsevier.com [accessed on May 10, 2020]).
  7. ↑ B. Andrews, D. Aisenberg, G. d'Avossa, A. Sapir: Cross-cultural effects on the Assumed light source direction: Evidence from English and Hebrew readers . In: Journal of Vision . tape 13 , no. 13 , November 1, 2013, ISSN  1534-7362 , p. 2–2 , doi : 10.1167 / 13.13.2 ( arvojournals.org [accessed May 10, 2020]).
  8. ^ Johan Wagemans, Andrea J Van Doorn, Jan J Koenderink: The Shading Cue in Context . In: i-Perception . tape I , no. 3 , December 2010, p. 159–177 , doi : 10.1068 / i0401 ( sagepub.com [accessed May 10, 2020]).
  9. ↑ Wendy J Adams: Frames of reference for the light-from-above prior in visual search and shape judgments . In: Cognition . tape 107 , no. 1 , April 2008, p. 137–150 , doi : 10.1016 / j.cognition.2007.08.006 ( elsevier.com [accessed May 10, 2020]).
  10. ↑ Michael Barnett-Cowan, Marc O. Ernst, Heinrich H. Bülthoff: Gravity-dependent change in the 'light-from-above' prior . In: Scientific Reports . tape 8 , no. 1 , December 2018, ISSN  2045-2322 , p. 15131 , doi : 10.1038 / s41598-018-33625-2 ( nature.com [accessed May 10, 2020]).