How to Change Your Mind: What the New Science of Psychedelics Teaches Us About Consciousness, Dying, Addiction, Depression, and Transcendence

by Michael Pollan

WHAT HAPPENS WHEN, under the influence of psychedelics, the usually firm handshake between brain and world breaks down? No one thing, as it turns out. I asked Carhart-Harris whether the tripping brain favors top-down predictions or bottom-up sensory data. “That’s the classic dilemma,” he suggested: whether the mind, unconstrained, will tend to favor its priors or the evidence of its senses. “You do often find a kind of impetuousness or overzealousness on the part of the priors, as when you see faces in the clouds.” Eager to make sense of the data rushing in, the brain leaps to erroneous conclusions and, sometimes, a hallucination results. (The paranoid does much the same thing, ferociously imposing a false narrative on the stream of incoming information.) But in other cases, the reducing valve opens wide to admit lots more information, unedited and sometimes welcome.