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Spatial distortions and processing latencies in the onset repulsion and Fröhlich effects
Dirk Kerzel1, Karl R Gegenfurtner
1Justus-Liebig-Universität Giessen, FB 06 Psychologie und Sportwissenschaft, Otto-Behaghel-Strasse 10F, 35394 Giessen, Germany. dirk.kerzel@psychol.uni-giessen.de
Vision Research
|December 25, 2003
Summary
The Fröhlich illusion causes mis-localization of moving targets. Our study reconciles conflicting error patterns using natural pointing, revealing two independent factors influencing perceived target position.
Area of Science:
- Visual perception
- Human motor control
- Psychophysics
Background:
- The Fröhlich illusion demonstrates forward mis-localization of moving targets.
- The onset repulsion effect shows backward mis-localization.
- Previous methods struggled to reconcile these opposing effects.
Purpose of the Study:
- To reconcile conflicting error patterns in visual target localization.
- To investigate the influence of target velocity on perceived position.
- To differentiate between visual perception and motor response biases.
Main Methods:
- Utilized natural pointing movements for target localization.
- Employed a wide range of target velocities.
- Collected both motor judgments (pointing) and probe judgments.
Main Results:
- Target displacement increased in the direction of motion with velocity.
- A linear relationship between velocity and displacement was observed.
- This relationship was shifted opposite to the direction of target motion in motor judgments.
Conclusions:
- Onset localization is influenced by an attentional delay, explaining the Fröhlich illusion.
- Motor judgments exhibit an additional offset bias, potentially due to attentional repulsion.
- Two independent factors likely govern visual onset localization and motor response.