Short-term monocular deprivation in healthy humans: a meta-analysis and new perspectives

Starting from the early 2010s, several studies have shown that a short period of monocular deprivation in adult volunteers transiently shifts ocular dominance in favour of the deprived eye. We compiled a meta-analysis of 73 such studies and found that the shift of ocular dominance was reliably observed, although with variable effect sizes mainly associated with the duration of deprivation and the technique used for measuring ocular dominance. By contrast, the effect was remarkably stable across experimental designs (translucent versus light-tight patching of the dominant versus non-dominant eye). A qualitatively similar effect was also elicited without deprivation, by distorting the monocular image or making it task irrelevant. These results offer insights into the mechanisms underlying the ocular dominance shift, which we discuss in the light of current models and a new perspective inspired by predictive coding. This line of research allows for a new understanding of the plasticity of early visual processing, which perdures well after the end of developmental critical periods and may be used to promote recovery of visual functions.