“…We used a type of secondary reward, i.e., monetary compensation, in the current study. It should be noted that other forms of reward, including endogenous rewards associated with the primary task (Xue et al, 2015 ), primary rewards, such as water (Seitz et al, 2009 ) and juice (Imai, Kim, Sasaki, & Watanabe, 2014 ), and social reward (Hayward, Pereira, Otto, & Ristic, 2018 ), have also been found to be effective in initiating and/or improving perceptual learning. Whether there is a single mechanism for the different forms of reward or there are multiple reinforcement processes that differentially modulate visual perceptual learning remains to be elucidated.…”