Using data collected from mother-reared infants in the home cage we performed factor analysis to generate behavioral dimensions from behaviors averaged over the 18th through the 24th weeks of life, a developmental stage during which infants are being weaned by their mothers and begin to spend much of their time interacting with other members of the social group and exploring. Factor analysis was also performed on behaviors collected during the intruder challenge test. In each instance, principal components analysis, followed by standard orthogonal (Varimax) normalized rotation, was performed, and factor scores were generated for each individual. Behavioral dimensions were labeled by investigators with expertise in primate behavior, and were consistent with factors that have been generated by other primatologists studying temperamental differences 34 or responses to an intruder 35. The behavioral dimensions generated were then used as dependent variables in ANOVA, to test the hypothesis that animals carrying the -2232 G allele (carried on the rhCRH H2 haplotype) would show different scores on one or more behavioral dimensions. Because age and sex are known to influence responses to an intruder, age (adult vs. subadult) and sex (male vs. female) were included as independent measures for these analyses.
