Andy Clark has posted a clear and interesting piece on neural bandwidth, prediction and the construction of experience by the brain.
Perception may best be seen as what has sometimes been described as a process of “controlled hallucination” (Ramesh Jain) in which we (or rather, various parts of our brains) try to predict what is out there, using the incoming signal more as a means of tuning and nuancing the predictions rather than as a rich (and bandwidth-costly) encoding of the state of the world. This in turn underlines the surprising extent to which the structure of our expectations (both conscious and non-conscious) may quite literally be determining much of what we see, hear and feel.
Finally, perception and understanding would also be revealed as close cousins. For to perceive the world in this way is to deploy knowledge not just about how the sensory signal should be right now, but about how it will probably change and evolve over time. For it is only by means of such longer-term and larger-scale knowledge that we can robustly match the incoming signal, moment to moment, with apt expectations (predictions). To know that (to know how the present sensory signal is likely to change and evolve over time) just is to understand a lot about how the world is, and the kinds of entity and event that populate it. Creatures deploying this strategy, when they see the grass twitch in just that certain way, are already expecting to see the tasty prey emerge, and already expecting to feel the sensations of their own muscles tensing to pounce. But an animal, or machine, that has that kind of grip on its world is already deep into the business of understanding that world.
