Abstract # 32:

Scheduled for Thursday, June 20, 2013 11:15 AM-11:30 AM: Session 4 (San Geronimo Ballroom C) Oral Presentation


LATERALIZED SCRATCHING IN THE COMMON MARMOSET (CALLITHRIX JACCHUS)

S. J. Neal, M. G. Rice, M. A. Ritzer, J. R. Wombolt and N. G. Caine
333 S. Twin Oaks Valley Rd. , San Marcos, CA 92096, USA
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Scratching is a reliable indicator of anxiety in non-human primates. Chimpanzees are lateralized in their scratching, demonstrating preferences for scratching on the left side with their right hand. Leavens (2004) proposes that greater activity in the right hemisphere during anxiety-provoking situations may cause greater sensitivity in the left hemispace. In the current study, we investigated scratching in common marmosets (Callithrix jacchus). We recorded hand use and scratching using all-occurrences sampling in nine common marmosets housed naturalistically at Animal Educators in Valley Center, California. We gathered data in one hour observation periods twice per week from November 2011 to January 2013, until each subject had at least 300 instances of hand use, including grabbing food and active investigation of the environment, and 115 observations of scratching. Paired samples t-tests revealed that marmosets scratched significantly more with their left (M = 21.44, SD = 13.56) rather than right (M = 18.67, SD = 13.13) hands, t(8) = -3.20, p = 0.013, and the left-hand preference was evident regardless of overall hand preferences. However, the marmosets did not scratch significantly more (p>.05) in the left hemispace, which may suggest a general left side motor bias (left hand preferences) associated with mild anxiety in this species. These results suggest potentially interesting species differences in the neuroanatomical basis of arousal in primates.