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Independent hemispheric attentional systems mediate visual search in split-brain patients
S J Luck1, S A Hillyard, G R Mangun
1Department of Neurosciences, University of California, San Diego, La Jolla 92093.
Nature
|November 30, 1989
Summary
Split-brain patients demonstrate that each cerebral hemisphere can independently deploy spatial attention. This finding suggests distinct neural systems for visual search and voluntary attention orienting.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Visual Perception
Background:
- The primate visual system effectively identifies objects amidst distractions.
- Spatial selective attention, like a spotlight, is theorized to focus processing resources.
- Prior research indicated a unified attentional focus even in split-brain patients.
Purpose of the Study:
- To investigate the nature of spatial attention in split-brain patients during visual search.
- To determine if attention is unified or can be independently deployed by each hemisphere.
- To differentiate the attentional systems involved in visual search and voluntary attention.
Main Methods:
- Utilized a visual search task with bilateral stimulus arrays.
- Compared search rates in split-brain subjects versus normal control subjects.
- Assessed the deployment of attention in surgically separated cerebral hemispheres.
Main Results:
- Split-brain subjects scanned bilateral arrays at a faster rate than controls.
- Each surgically separated hemisphere deployed an independent focus of attention.
- Evidence suggests a dissociation between visual search and voluntary attention mechanisms.
Conclusions:
- The attentional system for visual search operates independently in each hemisphere of split-brain patients.
- This finding challenges the notion of a single, unified spotlight of attention for all tasks.
- The study highlights functionally and anatomically distinct attentional systems for visual search and voluntary orienting.