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The induced Roelofs effect: two visual systems or the shift of a single reference frame?
Paul Dassonville1, Bruce Bridgeman, Jagdeep Kaur Bala
1Department of Psychology and Institute of Neuroscience, 1227 University of Oregon, Eugene, OR 97403-1227, USA. prd@darkwing.uoregon.edu
Vision Research
|December 25, 2003
Summary
Cognitive location judgments are distorted by visual frame offsets, but sensorimotor responses are not. This study supports a biased-midline hypothesis, suggesting a single, shifted frame of reference influences perception and action.
Area of Science:
- Cognitive psychology
- Neuroscience
- Visual perception
Background:
- Cognitive judgments of object location are susceptible to visual illusions, like the Roelofs illusion, where a frame offset distorts perceived position.
- Sensorimotor responses, such as pointing, appear unaffected by these illusions, traditionally suggesting separate visual processing pathways.
Purpose of the Study:
- To investigate the underlying mechanisms of the dissociation between cognitive and sensorimotor spatial judgments under visual frame offsets.
- To test the alternative biased-midline hypothesis against the traditional dissociation theory.
Main Methods:
- Two laboratories employed a paradigm where participants indicated the direction symmetrically opposite a target's position.
- Behavioral data from cognitive judgments and sensorimotor responses were collected and analyzed.
Main Results:
- The observed behavioral dissociation between cognitive and sensorimotor responses is consistent with a single frame of reference whose origin (apparent midline) is biased.
- Qualitatively distinct predictions of the biased-midline hypothesis were supported by the experimental findings.
Conclusions:
- The findings challenge the traditional view of separate visual processing for cognitive and sensorimotor tasks.
- Evidence strongly supports the biased-midline hypothesis, proposing a unified spatial reference frame influenced by contextual cues.