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Student Prize Award Abstract
1996 Oral Paper Award


M.A. Hook-Costigan and L.J. Rogers
Department of Physiology, University of New England, Armidale, N.S.W. Australia, 2351.

We have found that the common marmoset (Callithrix jacchus) displays lateralization of hand use for spontaneous reaching for stationary food objects and for visuospatial reaching, foot use, mouth and eye use, and asymmetry in production of facial expressions. While lateralization of hand, mouth and foot use was present at the individual level, there was no evidence of a group bias for these behavioural functions. Individuals had a division of function between the hemispheres for these motor behaviours (eg. if the left hand is preferred for spontaneous reaching the right hand is preferred for visuospatial reaching). Eye preferences were measured in a monocular viewing situation. Facial expressions were induced by presentation of a fear-eliciting visual stimulus. Lateralization of eye preference and asymmetries in the production of facial expression were present at both the individual and group level. Like humans and rhesus monkeys, the marmosets displayed a right-eye preference in monocular viewing situations and a left-side bias when producing a fearful facial expression. In summary, in marmosets there is a dissociation between hand preferences and the lateralization of facial expression and eye dominance. The group bias for the latter asymmetries may indicate that the evolution of hemispheric specialization originated for perception rather than for manual control, as proposed by a number of authors. Hemispheric specializations for perceptual and emotional/communicative functions may have established a framework for the organization of later evolving hemispheric specializations of manual function.

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