Predicting Infant Enterprise From Early Relationships in Rhesus Macaques

Abstract

The enterprise of rhesus monkey infants was assessed at 3-6 weeks, in terms of the maximum distances to which they moved away from their mothers, and at 37-44 weeks, in terms of the number of raisins taken in a series of tests in test compartments accessible to the infants but not to their mothers. Between weeks 6 and 37, enterprise in infants changed from low to high, remained low, decreased from high to low, or remained high, and our data let us test hypotheses about the effects of early maternal restriction, early social experience, and exposure to risk on these changes. We were able to refute the view that high levels of early maternal restriction were associated with high levels of late enteprise, for infants changed from low to high levels of enterprise in spite of having been restricted at low rates, and in other cases high levels of enterprise were maintained in spite of low levels of maternal restriction. Levesl of early enterprise were unrelated to early levels of social involvement with companions other than mother, and changes in enterprise were not associated with social involvement. This study confirmed that experience of risk can enhance enterprise, for infants showing increases in enterprise were more at risk because their mothers were not top-ranking, or because they had highly aggressive mothers, or because they were in a group in which there was an aggressive adult male. In contrast, the enterprise of infants with top-ranking mothers which were not aggressive decreased. The value of the classification approach used in this study was discussed. When a high proportion of the subjects produces variable data, large numbers are needed to provide cases about whose scores we are confident. Given enough cases, however, hypothesis testing can become more specific than is possible with simple correlational approaches.