Hand preference predicts reactions to novel foods and predators in marmosets (Callithrix geoffroyi).

In chimpanzees (Pan troglodytes) and common marmosets (Callithrix jacchus), left-handed individuals are less likely than right-handed individuals to explore new objects and situations, suggesting a relationship between the hemispheric specialization of emotional states and motor function. To further explore this relationship and to test the hypothesis that fearfulness is related to hand preference, we assessed willingness to approach, sniff, and taste novel foods, and the duration of freeze reactions in response to hawk calls, in 18 Geoffroy's marmosets (Callithrix geoffroyi). In accordance with these hypotheses, left-handed marmosets were slower to explore novel foods and slower to emerge from a freeze response than right-handed marmosets. Hand preference and at least some features of temperament seem to be related in this and other species of primates.