 Neural explanations of binocular rivalry concern competition at some level of visual processing: (a) “interocular” competition between monocular neurons early in the visual system, namely visual neurons that receive input from only one eye or (b) competition between binocular neurons later in the visual system, namely neurons that receive input from both eyes. The winner of competition fixes which stimulus the subject experiences at a given time. Some of the earliest electrophysiological studies (Leopold &amp; Logothetis 1996; Logothetis, Leopold, &amp; Sheinberg 1996) on awake behaving monkeys supported later binocular processing as the neural basis of binocular rivalry. Processing in later (inferotemporal cortex, IT; see  figure 1)  rather than earlier visual areas (V1 or V2) were observed to be best correlated to the monkey’s reported perception based on the monkey’s stimuli-specific response. In contrast, imaging studies in humans suggested that neural activity in V1 did correlate with alternation. For example, Polonsky et al. used fMRI to demonstrate that V1 activity to competing stimuli tracked perception (Polonsky et al. 2000; but see Maier et al. 2008).