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Updated: Feb 7, 2026
06:49
Phase Contrast and Differential Interference Contrast DIC Microscopy
Published on: August 6, 2008
54.1K
When the weaker conquer: A contrast-dependent illusion of visual numerosity.
Quan Lei1,2, Adam Reeves1
1Department of Psychology, Northeastern University, Boston, MA, USA.
Journal of Vision
|July 21, 2018
Summary
Low-contrast visual elements appear more numerous than high-contrast ones in a new illusion. This "weak conquer the strong" effect occurs when elements are mixed, but not when separated.
Area of Science:
- Cognitive psychology
- Visual perception
- Psychophysics
Background:
- Humans and other species can estimate large set sizes (numerosity).
- Visual numerosity perception is influenced by factors like luminance contrast.
Purpose of the Study:
- Investigate the effect of luminance contrast on perceived numerosity.
- Report a novel numerosity illusion termed 'the weak conquer the strong'.
Main Methods:
- Presented intermixed displays of low- and high-contrast disks.
- Assessed perceived numerosity by matching to isolated element sets.
- Varied contrast sign (positive/negative) and spatial segregation.
Main Results:
- Low-contrast elements were perceived as more numerous than high-contrast ones when intermixed.
- The illusion occurred for same-sign contrasts but not opposite-sign contrasts.
- Spatial segregation eliminated the illusion, with both contrast types appearing equally numerous.
Conclusions:
- The illusion arises from the loss of high-contrast elements during perception.
- Failure in visual segregation and contrast normalization may explain the effect.
- Perceived numerosity is sensitive to subtle changes in element contrast.
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