Effect of practice on hand preference on a color visual discrimination task by capuchin monkeys (Cebus apella).

Effects of practice on hand preference in nonhuman primates have indicated an initial right-hemispheric advantage in new tasks that can be reversed or disappear after a long period of training. The aim of this study was to examine the effects of 6-mo. practice on hand preference in capuchin monkeys (Cebus apella) performing a color visual discrimination task which requires attention and learning or memory processes. For this purpose, an early period of practice (first 200 trials) was compared with a late period of practice (the last 200 trials after 6 mo. practice). No population-level biases were observed between the use of hands either early in training or after 6 mo. of practice. Individual analysis indicated that two of the five subjects tested strengthened their initial hand preference but three subjects changed their preference with the practice. No correlation was observed between hand use and performance. These results suggest that hand preference in capuchin monkeys can be influenced by practice and is not only a direct function of hemispheric specialization.