The distinct modes of vision offered by feedforward and recurrent processing

An analysis of response latencies shows that when an image is presented to the visual system, neuronal activity is rapidly routed to a large number of visual areas. However, the activity of cortical neurons is not determined by this feedforward sweep alone. Horizontal connections within areas, and h igher areas providing feedback, result in dynamic changes in tuning. The di fferences between feedforward and recurrent processing could prove pivotal in understanding the distinctions between attentive and pre-attentive visio n as well as between conscious and unconscious vision. The feedforward swee p rapidly groups feature constellations that are hardwired in the visual br ain, yet is probably incapable of yielding visual awareness; in many cases, recurrent processing is necessary before the features of an object are att entively grouped and the stimulus can enter consciousness.