This is a very interesting article in the NYT. It argues the brain works by predicting outcomes and then focusing on deviations from what was expected. This conserves neural "bandwidth", in much the same way that a JPEG file gets compressed by predicting the states of pixels in a region and only recording the deviations.
All this, if true, has much more than merely engineering significance. For it suggests that 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.