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Split brain: divided perception but undivided consciousness| old_uid | 12988 |
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| title | Split brain: divided perception but undivided consciousness |
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| start_date | 2017/02/27 |
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| schedule | 16h |
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| online | no |
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| details | Host: Patrick Haggard |
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| summary | In extensive studies with two split-brain patients, we replicate the standard finding that stimuli cannot be compared across visual half-fields, indicating that each hemisphere processes information independently of the other. Yet, crucially, we show that the canonical textbook findings that a split-brain patient can only respond to stimuli in the left visual half-field with the left hand, and to stimuli in the right visual half-field with the right hand and verbally, are not universally true. Across a wide variety of tasks, split-brain patients with a complete and radiologically confirmed transection of the corpus callosum showed full awareness of presence, and well above chance-level recognition of location, orientation and identity of stimuli throughout the entire visual field, irrespective of response type (left hand, right hand, or verbally). Crucially, we used confidence ratings to assess conscious awareness. This revealed that also on high confidence trials response type did not affect performance. These findings suggest that severing the cortical connections between hemispheres splits visual perception, but does not create two independent conscious perceivers within one brain. These findings have clear theoretical repercussions. Both the Information Integration Theory and the Global Workspace Theory imply that severing the corpus callosum should lead to a split in consciousness. The proposed model of the split-brain phenomenon is, therefore, a challenge to both these theories. |
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| responsibles | Lawrence |
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