Hand preference study in marmosets (Callithrix jacchus) using food reaching tests

Hand preference has been investigated in New World primates but the data ob tained thus far are controversial. In this study we investigated hand prefe rence in common marmosets, Callithrix jacchus, during the execution of a re aching for food task. We used 46 adult common marmoset males (n = 27) and f emales (n = 19) from the Universidade of Rio Grande do Norte colony, both w ild and captive-born. To test the hand preference we used a device measurin g 10 cm(2), with a central hole 1 cm in diameter, to force the animal to us e only one hand to reach for food on a food dish located underneath. Each a nimal was tested 5 times and had to make a maximum of 20 successful attempt s per session. A total of 100 successful attempts per animal and 4,600 succ essful attempts for all animals were recorded during the experiment. Latenc y and duration of the sessions were measured and we found preference for th e use of one of the hands in common marmoset individuals, i.e. 45 of total of 46 animals used significantly more the right or the left hand when perfo rming the task. However no bias at the population level was found. Females born in captivity presented an increase in the duration of latency for the First successful attempt and in the total duration of the test sessions. Th ese findings might he indicating differences associated with a natural tend ency for females to be more selective and to spend more time exploring alim entary sources. Additionally, captive-born females may have a constrain in developing cognitive abilities regarding foraging since they have food avai lable during most part of the time.