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Inversion produces opposite size illusions for faces and bodies
Eamonn Walsh1, Alexandra Vormberg2, Josie Hannaford3
1Department of Psychological Sciences, Birkbeck, University of London, UK; Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK.
Acta Psychologica
|September 9, 2018
Summary
The face size illusion, where inverted faces appear larger, is category-specific. This study found upright bodies were perceived as larger than inverted ones, unlike faces, hands, or objects.
Area of Science:
- Visual perception
- Cognitive psychology
- Neuroscience
Background:
- Faces are complex visual stimuli.
- An established illusion shows inverted faces appear larger than upright faces.
- The specificity of this face size illusion is not well understood.
Purpose of the Study:
- To investigate the category specificity of the face size illusion.
- To determine if similar illusions occur for bodies, hands, and objects.
- To explore the role of featural information versus contrast polarity in the face illusion.
Main Methods:
- Replication of the face size illusion with upright and inverted faces.
- Testing size perception for upright and inverted bodies, hands, and objects.
- Manipulating contrast polarity of face stimuli to assess reliance on featural information.
Main Results:
- The face size illusion was replicated.
- No size illusion was observed for hands or everyday objects.
- A reverse size illusion for bodies (upright perceived as larger) was observed but not statistically significant.
- The face illusion persisted regardless of contrast polarity, suggesting reliance on geometric features.
Conclusions:
- Size illusions due to inversion are highly category-specific.
- Faces and bodies exhibit opposite, category-dependent size illusions.
- Visual processing of faces and bodies differs in response to inversion.
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