Assessing the kaleidoscope of monocular deprivation effects.

Short-term monocular deprivation (∼150 min) temporarily shifts sensory eye balance in favor of the deprived eye (Lunghi, Burr, & Morrone, 2011; Zhou, Clavagnier, & Hess, 2013), opposite to classic deprivation studies (Hubel & Wiesel, 1970). Various types of deprivation-light-tight, diffuser lenses, image degradation-have been tested, and it seemed that a deprivation of contrast was necessary, and sufficient, for these shifts. This could be accommodated in a feedforward model of binocular combination (Meese, Georgeson, & Baker, 2006; Sperling & Ding, 2010), in which the shift reflects a (persistent) reweighting induced by an interocular gain control mechanism tasked with maintaining binocular balance (Zhou, Clavagnier, et al., 2013). Here, we used a novel "kaleidoscopic" monocular deprivation that, although it rendered images fractionated and uninformative, preserved gross luminance, color, spatial frequency, motion, and contrast information, effectively sneaking the image degradation past early, feedforward mechanisms, targeting higher levels. Kaleidoscopic deprivation produced effects indistinguishable from traditional light-tight patching. This rules out contrast imbalance as the sole factor driving these shifts in sensory eye balance. In addition, since the suppression of the kaleidoscopic image likely requires feedback from higher-level processes capable of determining the behavioral relevance of an eye's information (Foley & Miyanshi, 1969; Jiang, Costello, & He, 2007; Kovács, Papathomas, Yang, & Fehér, 1996; Wolf & Hochstein, 2011), feedforward-only models may need to be elaborated.