Incognito: The Secret Lives Of The Brain
by David Eagleman
Rating: 3.0 / 5 · Read · Finished 2025-12-13
A book by a neuroscientist about the unconscious mind. Main idea: You are not conscious of 99% of what your brain does. Conscious thought is only for a tiny minority of tasks.
I skipped several chapters because they were boring. Much of the other chapters I already knew. I had the best time reading this book when I skimmed and stopped at anything interesting.
Random thoughts while reading:
- Your conscious mind is like an LLM agent with context retrieval. You are not aware of the position of your tongue until you pay attention to it (bring it into context)
- Your brain performs the opposite of mindfulness most of the time. It keeps most of what your experience out of mind and only surface the unexpected things.
- It takes time for people who regain sight to learn to interpret the signals. For a while, their brain receives input but it makes no sense to them. It’s like how a written foreign language looks unintelligible, but eventually passes information directly into your brain.
- Some people go blind but don’t think they are blind. Their brain predicts what they would see and presents it to the conscious mind.
- Other people go blind because their visual cortex is damaged, but other parts of the brain partially make up for it. They can’t see, but when they are asked to guess what’s in front of them, they guess more accurately than random chance.
- Push a button to flash a light. Then add a small delay. Your brain calibrates so they still seem simultaneous. Remove the delay and the flash appears before pressing the button.
- The book has a section “Why do we have consciousness at all?”. Answer in a quote: “From an evolutionary point of view, the purpose of consciousness seems to be this: an animal composed of a giant collection of zombie systems would be energy efficient but cognitively inflexible. It would have economical programs for doing particular, simple tasks, but it wouldn’t have rapid ways of switching between programs or setting goals to become expert in novel and unexpected tasks. In the animal kingdom, most animals do certain things very well (say, prying seeds from the inside of a pine cone), while only a few species (such as humans) have the flexibility to dynamically develop new software.
- Quote: “The brain has developed multiple, redundant ways is solving problems.” This reminds me of findings from Anthropic’s mechanistic interpretability research where they found that LLMs have multiple pathways to activate features.
- The back of the book says “What do Odysseus and the subprime mortgage meltdown have in common?” The answer is that we have short-term and long-term oriented parts of the brain, and they conflict with each other. Odysseus’ long-term brain tied himself up so the short-term brain wouldn’t jump into the sea after sirens. People took mortgages they couldn’t afford because they were thinking short-term.