Gc. Westergaard et al., EFFECTS OF UPRIGHT POSTURE ON HAND PREFERENCE FOR REACHING VS. THE USE OF PROBING TOOLS BY TUFTED CAPUCHINS (CEBUS-APELLA), American journal of primatology, 44(2), 1998, pp. 147-153
This research examined the effects of task (reaching vs. tool use) and
posture (quadrupedal vs. bipedal) on hand preference in tufted capuch
ins (Cebus apella). Regarding direction of hand preference, we found a
significant main effect of posture, as the bipedal stance elicited gr
eater use of the right hand than did the quadrupedal stance, and a sig
nificant posture x task interaction, as bipedal reaching elicited grea
ter use of the right hand than did other postural and task conditions.
Further, we found a significant main effect of task on strength of ha
nd preference, as tool use elicited more consistent use of one hand ov
er the other than did reaching. Our findings indicate that bipedal rea
ching facilitates a mild right-hand bias in intensely manipulative pri
mates. We speculate that this moderate bias may have been pushed in th
e direction of nearly exclusive right-hand preference in most humans w
ith the development of complex tool use. (C) 1998 Wiley-Liss, Inc.dagg
er.