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Biases and sensitivities in geometrical illusions
journal contribution
posted on 2023-06-07, 18:31 authored by M J Morgan, Graham Hole, A GlennersterPsychometric functions were collected to measure biases and sensitivities in certain classical illusory configurations, such as the Muller-Lyer. We found that sensitivities (thresholds or just noticeable differences) were generally not affected by the introduction of illusory biases, and the implications of this for theories of the illusions are discussed. Experiments on the Muller-Lyer figure showed that the effect depends upon mis-location of the ends of the figure, rather than upon a global expansion as demanded by the size-constancy theory. A new illusion is described in which the perceived position of a dot is displaced towards the centre of a surrounding cluster of dots, even though it is clearly discriminable from other members of the cluster by their colour. We argue that illusions illustrate powerful constraints upon visual processing: they arise when subjects are instructed to carry out a taks to which the visual system is not adapted.
History
Publication status
- Published
Journal
Vision ResearchISSN
00426989External DOI
Issue
11Volume
30Page range
1793-1810Department affiliated with
- Psychology Publications
Full text available
- No
Peer reviewed?
- Yes