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Length illusions in conventional and single-wing Müller-Lyer stimuli
1Department of Psychology, University of Sydney, NSW, Australia. johnp@psych.usyd.edu.au
Perception & Psychophysics
|September 21, 2000
Summary
Removing one wing from Müller-Lyer figures equally reduced both contraction and expansion illusions. Illusory effects were concentrated near the angles for both acute and obtuse figures, challenging prior findings.
Area of Science:
- Visual perception
- Psychophysics
- Cognitive psychology
Background:
- The Müller-Lyer illusion involves two-wing figures creating length distortions.
- Previous research indicated asymmetrical effects of wing removal on acute vs. obtuse angles.
Purpose of the Study:
- To re-evaluate Warren and Bashford's (1977) findings on the Müller-Lyer illusion.
- To investigate the impact of removing one wing component on illusion magnitude and distribution.
Main Methods:
- Four experiments were conducted, including length matching and line bisection tasks.
- Participants adjusted lines to match Müller-Lyer figures or vice versa.
- Bisection tasks assessed error distribution along the figure's shaft.
Main Results:
- Removing one wing component reduced both acute-angle (contraction) and obtuse-angle (expansion) illusions similarly.
- Bisection errors were concentrated near the angles for both illusion types.
- Prior findings of differential effects were not replicated.
Conclusions:
- The study's results align with traditional theories of the Müller-Lyer illusion.
- Illusionary effects are primarily localized to the shaft regions adjacent to the angle components.
- Asymmetrical effects reported by Warren and Bashford were not supported.