Split Brain Research: A Cautionary Tale of Sloppy Science

A response to CGP Grey's video You are Two, as well as a larger exploration of the literature on split brain patients. Grey's Video: https://www.youtube.com/watch?v=wfYbgdo8e-8&t=184s Patreon: https://www.patreon.com/TheArtofDeduction References: (My reference list exceeded the youtube description character limit, so I've put them in a Google doc which you can view at the link below) https://docs.google.com/document/d/1I3YGszjRlPHgTPSAwSwicPhdRfK7o2T5geQnlG01NVQ/edit?usp=sharing The video is quite long so here's an overview: Split brain surgery (callosotomy) was developed in the 1940's as a surgical treatment option for intractable epilepsy. After this procedure was conducted on a number of individuals, researchers named Roger Sperry, Michael Gazzaniga, and Joseph Bogen began conducting tests on these patients to see if there were any changes to their psychology, behavior, or overall functioning. While these patients were shown to have no change to their overall intelligence or their personalities, they were shown to no longer be able to verbally describe sensory information presented to their left side (Right hemisphere), but their left hand (controlled by the right hemisphere) could interact with such stimuli. This led to speculation in the psychological literature that a callosotomy created two conscious agents, one of which was verbal and the other mute. However, more recent research has shown that while a split brain patient cannot verbally describe visual information presented to their right hemisphere, they are able to verbally demonstrate conscious awareness of it, demonstrating that the original theory of Gazzaniga and Sperry that the split brain is composed of two conscious agents is likely untrue, and that this merely boils down to an inability to integrate lateralized cognitive functions with the sensory experiences of the other hemisphere and that the person is fully aware of everything both halves of their brain processes. We then take a deeper dive into the relationship between consciousness and identity, and how one's sense of identity might be a left-lateralized cognitive function which could explain why split brain patients show no change in personality because this cognitive function remains fully intact after a callosotomy. Chapters: 00:00:00 Introduction 00:08:50 Patreon Ad Break 00:11:38 A Brief History 00:23:46 Do You Have Two Brains? 00:33:20 The Research: Then vs Now 00:57:26 Language Lateralization: How does it work? 01:09:17 The Self and Consciousness 01:16:11 Operationalizing the Self 01:33:29 You Are Not Two 01:39:07 Conclusion 01:47:22 Credits