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Comment by ianhanschen | Hacker News Reader

I'm upvoting your comment but can you clarify on left brain/right brain? I thought split-brain/callosal syndrome showed us that a lot of our ideas about left brain right brain functional divide were true.

Edit for clarification: I was not expecting folks to respond to this by linking split-brain experiments; I am specifically referring to split-brain experiments showing us that our ideas about left brain/right brain were correct. This was in reply to "I'd agree with this author that they are oversimplified and generally incorrect - I'd add the left brain right brain divide to the list" -- I want to know what this person thinks, thanks.

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See Ian McGilchrist’s 2009 book The Master and His Emissary:

> McGilchrist digests study after study, replacing the popular and superficial notion of the hemispheres as respectively logical and creative in nature with the idea that they pay attention in fundamentally different ways, the left being detail-oriented, the right being whole-oriented.

[1] https://en.wikipedia.org/wiki/The_Master_and_His_Emissary

Without listing the actual misconceptions some people have, it's hard to say 'the left brain/right brain divide' is a misconception since I was already aware of this understanding that they just observe in different ways, not that "left brain is creative and right is logical". I grew up with the internet, though, so my understanding didn't solely originate from grade school science books that might be simplifying this phenomenon.

I get minor strokes every couple of months.

Each time I lose feeling in right side of body, and lose the ability to write. Not 100%, but close enough. Typing is fine however, if slow. Critical thinking goes to crap. Talking is fine. I can still draw, though my motivation goes to crap.

Is weird what stays and what goes.

Last time I looked writing is a left brain activity. Which controls right side.

Usually the right hemisphere is linked with comprehending speech/writing, rather than producing it, so it's interesting that you lose the ability to write. Is your speech affected at all? It could be because writing involves a bunch of other more domain-general brain functions too I guess.

I think he's talking about motor control - how the left hemisphere is responsible for controlling the right side of the body and vice versa.

Correct. Right side body is numb, cold and weak. So I assume issue is left side of brain.

I can read and speak well enough. Thinking is harder, so I tend to stay quiet.

My best understanding (which, it's been a while since I took classes about it) is that there are some functions that tend to be more lateralized to one hemisphere or another -- with language being the prime example. However, some people do show more balanced functioning, and in some cases (more frequently among left-handed people) the lateralized functions can even be flipped from "normal".

However, there's left-brain/right-brain in terms of "some functions of the brain tend to be more on one side or another", and then there's left-brain/right-brain in terms of a pseudoscientific personality test about whether you're more of a "logical" thinker or "artistic" thinker, blah blah blah. There's no evidence for that. It's just mumbo-jumbo Buzzfeed-style quizzes to make you feel good about yourself.

More accurately, in right-handed populations subjects there is good correlation between localized brain insults and specific functional deficits. The association between brain insult locations and specific functional deficits is less strongly correlated in left-handed people and certain other subpopulations. These are also very much tendencies and not predictors for individuals.

aha, thanks!

My son has total agenesis of corpus callosum and he is 100% asymptomatic. We discovered accidentally in the last ultrasound the doctor did and confirmed with magnetic resonance.

The brain is complex.

Edit: https://en.wikipedia.org/wiki/Agenesis_of_the_corpus_callosu...

Look into corpus callosum separation (split-brain) and some of the experiments that have been performed after this procedure. Fascinating displays of two separate consciousnesses. Sam Harris' Making Sense Podcast #234 had Iain McGilchrist to discuss this in some detail.

That is what I am referring to :)

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