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Brief Book Review - Reality Switch Technologies by Andrew Gallimore

2026 Aug 16


Brief Book Review - Reality Switch Technologies by Andrew Gallimore
  439 words

Book reviews · Psychopharmacology · Neuropharmacology · Qualia

(this is a light edit of a farcaster post that I made a few years ago.)

The first ~half of the book describes the default way the brain constructs a model of the world that we experience and collectively come to consensus about what that model contains. They call this the "consensus reality" that we inhabit during our waking moments. This is largely similar to the first half author's first book11.Which is a kind of bonkers book, but quite a fun read. Just don't take it very seriously. but in deeper detail. Then they go on to describe 4 "switches" that different drugs activate to alter the construction process for the models of reality that we experience.

First, there's the C-switch. It's activated by the classic psychedelics like psilocybin and LSD. This switch adds noise to the signals passed between neurons in the brain. It basically increases the brains prediction errors and heightens attention to sensory input. Details seem more prominent when this switch is activated, and familiar experiences take on a quality of novelty, or gain mild hallucinations.

The M-switch is activated by tropanes and deliriants like datura. They increases prediction errors like before, but now sensory input is inhibited and are not used to update the brains predictions at a normal rate. This results in very vivid hallucinations indistinguishable from reality. The brain is effectively allowed to conjure phenomena into your experience with little ability to use sensory input to suppress the hallucinations.

The N-switch activated by drugs like PCP and ketamine. This again increases prediction errors but through a different receptor from the 5htp2a receptors of the C-switch. This section also analyses the k-hole phenomenon, which I am unable describe.22.Read the book for details.

Finally there's the K-switch, activated by the salvinorin compounds found in salvia divinorum plants. They disrupt neurons in the claustrum, which as far as I understand is a brain region responsible for smoothly transitioning your experience from one moment to the next. It is basically the state transition function of experience. To do this the claustrum strongly inhibits any predictions your brain makes that are not validated by sensory input, this process is basically deactivated by salvia and the brains predictions are all slammed together into a single experience resulting in a feeling of reality tearing or ripping apart.

Overall the book was very interesting. Even if you are not particularly interested in the effects of psychedelic drugs, or the stimulation of particular receptors on neurons in the brain, I would still recommend this book to anyone interested in the way the brain works or how experience is created by the brain.


  1. Which is a kind of bonkers book, but quite a fun read. Just don't take it very seriously. ↩︎

  2. Read the book for details. ↩︎


2026 Aug 16 Book reviews · Psychopharmacology · Neuropharmacology · Qualia