How researchers discovered we have “two brains” [video]

Memory is a weird beast with many variables. A few things I know:

1. It's state dependent.

Example: I had a tortured first pregnancy and the birth was awful. For years, I couldn't clearly remember it.

Then I had a lengthy medical crisis that involved constant, excruciating pain. Suddenly, I could clearly remember the birth of my first child.

2. It's context dependent.

For example, people frequently fail to identify individuals they know if they run into them someplace they wouldn't expect to see them. They may realize they know the person, but just can't place them. (I have experienced this.)

This is also the mechanism behind going to do a thing, forgetting what it is, remembering when you return to where you were.

3. Emotion is a form of memory.

People with strong affect can make snap decisions based on "gut feeling." People with low affect cannot make snap decisions. They lack the file that sums up all their pertinent experiences as either "I have good feeling about this" or "I have a bad feeling about this."

4. "Muscle memory"

Some people think better while active. This is your stereotypical Pacer.

If you keep a dream journal, it's easier to remember dreams if you keep a pen and notebook on the nightstand and make notes without getting up at all. It's best to stay in bed and try to not leave your sleep position. Dreams can sometimes be retrieved by returning to whatever position you were laying in while dreaming.

5. Some people think in pictures. Some in words. This effects memory storage.

For most people, conscious recall of memory corresponds to learning to speak. It apparently heels people catalog their memories so the files are accessible.

I have a son who thinks in pictures. At some point, it became clear he could access pre-verbal memories, but it was like listening to someone translate a thing into English.

We actually went through a period where he waited until everyone else was asleep, then he would share his memories with me. Translating them to words from pictures helped him more readily access them.

There's no doubt tons more stuff to know about memory. This is very off the cuff.

Does anyone know why the left vs right hand behaves the way it does at the end of the video? Left as an exercise for us?

the graphics indeed failed to reflect the fact that each eye is split vertically into two fields of vision that go to separate brain hemispheres (the inner field going to the same-side hemisphere and the outer half going to the opposite), but the narration was accurate: focused on a point between two screens, the left hemisphere sees only the right screen, and visa versa.

The left hemisphere encodes tool use. Its preference for this is so strong that even left-handed folks encode tool-use in the left hemisphere, which means that the round trip from hand to brain goes left hand -> right hemisphere (b/c each hemisphere controls the opposite side of the body) -> left hemisphere (tool circuits) -> right hemisphere -> left hand, which is waaay less efficient than right hand -> left hem -> right hand. (https://www.ted.com/talks/iain_mcgilchrist_the_divided_brain)

So, the left hand's failure to pantomime screwdriver use probably reflects the commissurotomy patient's right hemisphere's inability to access her left hemisphere's knowledge of tools. (That this only happens when eyes are closed probably means the right hemisphere just observed and copied the right hand's behavior when eyes were open.)

Had a fun chat with someone interested in this at a bar a few weeks ago who offered a theory that the best pro basketball players are right hand/right eye dominant or left hand/left eye dominant, and that anybody with mixed dominance just can't cut it. Apparently the military just wont take you as a pilot or sniper if you have mixed hand/eye dominance?

Calling it now: laterality is central to who we are, and is currently underappreciated—especially in AI research (though I'd be delighted to hear from AI folks who disagree!).

EDIT: lots

Rich Hickey’s talk on “Hammock driven development” talks about this too and the idea of HDD is to load the information into your mind and then... wait. Relax. Allow your subconscious mind to process it and make connections between things. Then, after an amount of time (how long and how many times you repeat this depending on the complexity of the thing and whether you feel like you have some insight yet or not) you consciously think about it again. Hence “hammock driven development”: think about your problem to load it in, then chill in a hammock for a bit.