The dynamics of binocular rivalry also follow specific, nonintuitive properties relating input strength to percept duration, described by Levelt (
1968). The most striking result obtained by Levelt is known as his second proposition: When increasing the luminance or the contrast of the stimulus presented to one eye, while keeping constant the input to the other eye, the average percept duration for the manipulated eye did not change while percept duration decreased for the other eye. Brascamp, van Ee, Noest, Jacobs, & van den Berg (
2006) showed that this phenomenon was in fact valid only within a limited range of parameter values (see
Discussion). But even within this limited range, Levelt's result strongly constrains the underlying model: Rubin & Hupé (
2005) stated that it demanded that two independent populations of neurons coding the competing representations be functionally connected through reciprocal inhibition, as indeed implemented in most, if not all, models of binocular rivalry accounting for Levelt's laws (Lehky,
1988; Mueller & Blake,
1989; Wilson,
2003; Noest, van Ee, Nijs, & van Wezel,
2007; Seely & Chow,
2011; see more references in the supplemental information by Alais, Cass, O'Shea, & Blake,
2010). There is also psychophysical evidence revealing the dynamic inhibition of suppressed percepts, therefore supporting the reciprocal inhibition model (Alais et al.,
2010). In addition to coupling, key roles have been demonstrated for both adaptation (Suzuki & Grabowecky,
2002; Blake, Sobel, & Gilroy,
2003; Long & Toppino,
2004; Pastukhov & Braun,
2011) and noise (Brascamp et al.,
2006; Moreno-Bote, Rinzel, & Rubin,
2007; Shpiro, Moreno-Bote, Rubin, & Rinzel,
2009; Pastukhov et al.,
2013; Huguet, Rinzel, & Hupé,
2014) in triggering switches between the competing populations of neurons as the dominant response wanes.