But this assembly line model began to draw suspicion when it was discovered that brain wiring does not simply run from A to B to C: there are feedback loops from C to B, C to A, and B to A. Throughout the brain there is as much feedback as feedforward—a feature of brain wiring that is technically called recurrence and colloquially called loopiness.39 The whole system looks a lot more like a marketplace than an assembly line. To the careful observer, these features of the neurocircuitry immediately raise the possibility that visual perception is not a procession of data crunching that begins from the eyes and ends with some mysterious end point at the back of the brain. In fact, nested feedback connections are so extensive that the system can even run backward. That is, in contrast to the idea that primary sensory areas merely process input into successively more complex interpretations for the next highest area of the brain, the higher areas are also talking directly back to the lower ones.
