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288 pages, Hardcover
First published March 2, 2021
How a brain made of simple cells creates intelligence is a profoundly interesting question, and it remains a mystery.
... the older parts of the human brain control the basic functions of life. They create our emotions, our desires to survive and procreate, and our innate behaviors.
The new brain, the neocortex, is the organ of intelligence.
"The brain creates a predictive model. This just means that the brain continuously predicts what its inputs will be. Prediction isn’t something that the brain does every now and then; it is an intrinsic property that never stops, and it serves an essential role in learning. When the brain’s predictions are verified, that means the brain’s model of the world is accurate. A misprediction causes you to attend to the error and update the model."
"How can I speak confidently about a theory if it hasn’t been tested experimentally? I just described one of these situations. I had an insight that the neocortex is infused with reference frames, and I immediately started talking about it with certainty. [...] Here is why.
As we work on a problem, we uncover what I call constraints. Constraints are things that the solution to the problem must address. [...] The longer you work on a problem, the more constraints you discover and the harder it becomes to imagine a solution. The aha moments I described in this chapter were about problems that we worked on for years. Therefore, we understood these problems deeply and our list of constraints was long. The likelihood that a solution is correct increases exponentially with the number of constraints it satisfies. It is like solving a crossword puzzle: There are often several words that match an individual clue. If you pick one of those words, it could be wrong. If you find two intersecting words that work, then it is much more likely they are both correct. If you find ten intersecting words, the chance that they are all wrong is minuscule."
This is a good point to address a question I am often asked: How can I speak confidently about a theory if it hasn’t been tested experimentally? I just described one of these situations. I had an insight that the neocortex is infused with reference frames, and I immediately started talking about it with certainty. As I write this book, there is growing evidence to support this new idea, but it still has not been thoroughly tested. And yet, I have no hesitation describing this idea as a fact. Here is why.
As we work on a problem, we uncover what I call constraints. Constraints are things that the solution to the problem must address. I gave a few examples of constraints when describing sequence memory, for example, the Name That Tune requirement. The anatomy and physiology of the brain are also constraints. Brain theory must ultimately explain all the details of the brain, and a correct theory cannot violate any of those details.
The longer you work on a problem, the more constraints you discover and the harder it becomes to imagine a solution. The aha moments I described in this chapter were about problems that we worked on for years. Therefore, we understood these problems deeply and our list of constraints was long. The likelihood that a solution is correct increases exponentially with the number of constraints it satisfies. It is like solving a crossword puzzle: There are often several words that match an individual clue. If you pick one of those words, it could be wrong. If you find two intersecting words that work, then it is much more likely they are both correct. If you find ten intersecting words, the chance that they are all wrong is miniscule. You can write the answer in ink without any worries.
Aha moments occur when a new idea satisfies multiple constraints. The longer you have worked on a problem—and, consequently, the more constraints the solution resolves—the bigger the aha feeling and the more confident you are in trusting the answer. The idea that the neocortex is infused with reference frames solved so many constraints that I immediately knew it was correct.