18 may 2023

There was these famous experiments on split brain patients - people who’d had their corpus callosum (the connection between the two halves of their brain) severed as a last-ditch treatment for life-threatening epilepsy - performed by Roger Sperry and Michael Gazzaniga.

Because of how our eyes are wired to our brains, you can show a split-brain person an image such that only one half (hemisphere) of their brain can see it.

But language is highly lateralized. That means it mostly - almost exclusively - takes place on one half of the brain. In most people, it’s in the left hemisphere.

So you can show a split-brain person an image their left hemisphere can see, and if you ask them about it, they can describe it fine. If you show their right hemisphere the picture, they’ll tell you they see nothing - but if you ask them to point to matching picture, *their arm controled by the same half will point correctly.*

Then things get *really* weird.

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