Gregory's perspective theory of illusions

Get Revising

Created by: Ellsbells98
Created on: 31-05-15 11:12

View mindmap

Gregory's perspective theory of illusions
- To understand this theory, you need to remember size constancy (we perceive an object as the same size even when its distance from us changes).
- Distortion illusions often include angled lines, such as the 'fins' of the Muller-Lyer illusion and the radiating lines of the Hering illusion. According to Gregory, we interpret these patterns as if they were depth cues. We then apply constancy scaling and distort our perception.
- Gregory's theory is a good explanation for distortions. If angled lines are used as depth cues, this explains many illusions.
  - However, Gregory's theory cannot explain the version of the Muller-Lyer illusion with circles instead of fins as they do not provide cues to depth, so this version of the illusion shouldn't work, but it does.
- Gregory's theory can explain some ambiguous figures when the two alternative figures are perceived using depth cues.
  - E,g, on the Leepers Lady illusion, the nose of the young woman looks further away than the wart on the old woman's nose,
    - The Necker Cube illusion can be perceived as two different solids. This is ambiguous because the perspective cues can be interpreted in different ways. If this is prevented by adding more information about depth, the illusion goes away.
- Depth cues can also explain some fictions, e.g. the Kanizsa Triangle, as the 'brighter than white' triangle appears to jump out. The background of illusion seems further away. So the 'brighter than white' triangle is perceived as separate.