Chenyi Qian¹, Dorita H.F. Chang¹; ¹The University of Hong Kong

Recent work has shown that short-term monocular deprivation (MD) can alter sensory eye dominance (SED) among adults. Specifically, following deprivation, the deprived eye becomes more dominant. The challenge of unraveling the mechanism underlying deprivation-induced shifts of SED arises from the known task variability used to index it. Here, we aimed to examine the effects of MD on SED while contrasting the eye deprived (dominant vs. non-dominant) and the task used to index SED (phase combination and orientation rivalry tasks). Adults with normal vision underwent 2.5 hours of MD for each eye during two sessions separated by a 48-hour interval. We found that MD-induced shifts in SED were only evident when indexed by the phase combination task, and participants’ SED decreased more evidently when the non-dominant eye was deprived. Subsequently, we investigated whether the observed effects generalized to different yet analogous SED metrics. New observers were tested on a dichoptic motion task, requiring binocular integration (akin to the phase combination task) and a letter polarity (rivalry) task invoking binocular competition (akin to the orientation rivalry task). The new comparison revealed that MD-induced SED shifts were only evident in the letter polarity task. As for Experiment 1, deprivation of the non-dominant eye produced a greater reduction in SED than deprivation of the dominant eye. Our data suggest that deprivation-induced SED shifts are independent of task category but depend on the eye deprived, with the deprivation of the non-dominant eye consistently leading to a more balanced outcome. We speculate that the changes in SED induced by MD of the non-dominant eye reflect a homeostatic response that transiently lifts the gain control exerted by the dominant eye. Conversely, we expect a weaker release of gain control when the dominant eye is deprived, as it experiences less suppression from the other eye.