Perception is controlled hallucination

• The title is a quote from Surfing Uncertainty.
• We do not perceive “reality as it really is”. We start with top down predictions informed by what we (think we) know about the world and hold incoming data against those predictions.
• This is why mental models are so effective. They change the world you live in because they change the top down predictions your brain comes up with.
• In his Book Review: Surfing Uncertainty | Slate Star Codex, Scott sums it up like this:

  • To deal rapidly and fluently with an uncertain and noisy world, brains like ours have become masters of prediction – surfing the waves and noisy and ambiguous sensory stimulation by, in effect, trying to stay just ahead of them. A skilled surfer stays ‘in the pocket’: close to, yet just ahead of the place where the wave is breaking. This provides power and, when the wave breaks, it does not catch her. The brain’s task is not dissimilar. By constantly attempting to predict the incoming sensory signal we become able – in ways we shall soon explore in detail – to learn about the world around us and to engage that world in thought and action.

    The result is perception, which the PP theory describes as “controlled hallucination”. You’re not seeing the world as it is, exactly. You’re seeing your predictions about the world, cashed out as expected sensations, then shaped/constrained by the actual sense data. ⤴️

  • Top-down processing very occasionally meddles in bottom-up sensation, but (as long as you’re not schizophrenic), it sticks to an advisory role rather than being able to steamroll over arbitrary amounts of reality.

    The rationalist project is overcoming bias, and that requires both an admission that bias is possible, and a hope that there’s something other than bias which we can latch onto as a guide. Predictive processing gives us more confidence in both, and helps provide a convincing framework we can use to figure out what’s going on at all levels of cognition. ⤴️
• In another post, Scott (speaking to his new born twins), calls surprisal-minimization one of the two imperatives of their life (the other one being with active inference):

  • My poor, fragile, little cognitive engines! These, then, will be the twin imperatives of your life: surprisal minimization and active inference. If your brains are still too small to process such esoteric terms, there are others available. Your father’s ancestors called them Torah and tikkun olam; your mother’s ancestors called them Truth and Beauty; your current social sphere calls them Rationality and Effective Altruism. You will learn other names, too: no perspective can exhaust their infinite complexity. Whatever you call them, your lives will be spent in their service, pursuing them even unto that far-off and maybe-mythical point where they blur into One. ⤴️