Gc. Westergaard et Sj. Suomi, HAND PREFERENCE FOR A BIMANUAL TASK IN TUFTED CAPUCHINS (CEBUS-APELLA) AND RHESUS MACAQUES (MACACA-MULATTA), Journal of comparative psychology, 110(4), 1996, pp. 406-411
This research examined hand preference for a bimanual task in 45 tufte
d capuchin (Cebus apella) and 55 rhesus macaque (Macaca mulatta) monke
ys. Investigators presented subjects with plastic tubes lined with foo
d and noted which hand the animals used to hold the tubes and which ha
nd the animals used to remove the food. Several significant findings e
merged from this investigation. First, rhesus macaques, but not tufted
capuchins, exhibited a population-level bias toward use of the right
hand (although the difference in direction of hand preference between
species was not significant). Second, capuchins exhibited greater hand
preference strength than did macaques. Third, among capuchins, but no
t among macaques, hand preference strength was greater for adults than
for immatures. Finally, both species used their index digit to remove
food most frequently when compared with other digits. Findings of han
d preference direction and strength in this study were compared with o
ther findings noted for chimpanzees which performed a bimanual tube ta
sk in a previous study. The authors conclude that using the same proce
dure to compare hand preference across species represents a powerful r
esearch tool that can lead to a more complete understanding of the evo
lution and ontogenesis of primate handedness.