Abstract # 74:

Scheduled for Thursday, August 18, 2005 07:00 PM-09:00 PM: (Cambridge/Oxford Room) Poster Presentation


Left vs. Right Nipple Preference in Free-Ranging Infant Rhesus Macaques (Macaca mulatta)

B. D. Jaffe1, T. A. Evans1, S. Howell1, G. C. Westergaard1 and J. D. Higley2
1Alpha Genesis, Inc., 95 Castle Hall Rd , PO Box 557, Yemasee, SC 29945, USA, 2NIH/National Institute of Alcoholism and Alcohol Abuse
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     The examination of non-human primate lateralized behaviors may provide insight into the evolution of hemispheric specialization. This project examined nipple preference in 64 infant macaques in order to consider the implications of lateralized behavior. We used a focal animal sampling method to observe nipple contact during 15, 30-minute sessions throughout each infant‚s first year of life. Using an index (LBI) we calculated individual and population preferences (LBI =(R-L)/(R+L); R = mean right nipple contact, L = mean left nipple contact). Strength of preference was calculated as the absolute value of this score. Single sample t-tests were used to determine the presence and strength of a preference, independent measures t-tests were used to test sex and parity (primiparous vs. multiparous mothers) effects, and a Chi-Square was used to consider LBI between successive siblings (P < 0.05). Infants exhibited no population preference for a particular nipple (t = -0.02), but showed a significant strength of preference (t = 30.36) that developed after 48 hours. There were no significant sex or parity differences for preference (t = -0.33, t = -0.29) or strength (t = -0.24, t = -1.11). Interestingly, successive siblings preferred the nipple not used by the previous infant (χ2 = 19.17). These findings suggest that nipple preference is guided by external stimuli, and that nipple preference during infancy may not be a direct behavioral representation of hemispheric specialization.