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Updated: Jun 17, 2026
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Methods to Explore the Influence of Top-down Visual Processes on Motor Behavior
Published on: April 16, 2014
Paradoxical form of filled/empty optical illusion.
Jiri Wackermann1, Kristina Kastner
1Department of Empirical and Analytical Psychophysics, Institute for Frontier Areas of Psychology and Mental Health, Freiburg i.Br., Germany. jw@igpp.de.
Acta Neurobiologiae Experimentalis
|January 6, 2010
Summary
The Oppel-Kundt illusion, a geometric optical illusion, is influenced by the height of subdividing lines. Taller lines paradoxically reduce the illusion
Area of Science:
- Visual perception
- Geometric optical illusions
Background:
- The filled/empty illusion, also known as the Oppel-Kundt illusion, is a long-standing phenomenon in geometric optical illusions.
- The precise factors influencing the magnitude of this illusion are not fully understood.
Purpose of the Study:
- To investigate how the height of vertical subdividing strokes affects the magnitude of the filled/empty illusion.
- To determine if the spatial patterning, rather than just the number, of elements influences the illusion's strength.
Main Methods:
- Utilized the standard-variable matching psychophysical paradigm.
- Systematically varied the height of vertical strokes within a fixed spatial extension.
- Compared the illusory effect with different stroke heights relative to delimiting strokes.
Main Results:
- Consistent with prior research, shorter or equally tall strokes led to length over-reproduction.
- A paradoxical decrease in the illusory effect was observed when vertical strokes were three times taller than delimiting strokes.
- Negative illusory effects were recorded in some participants with taller strokes, indicating length under-reproduction.
Conclusions:
- The magnitude of the filled/empty illusion is dependent on the spatial patterning created by subdividing elements, not solely their quantity.
- Stroke height is a critical determinant, with taller elements potentially altering the perceived spatial division.
- Further research is needed to fully elucidate the complex mechanisms underlying the Oppel-Kundt illusion.
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