Assessing the Stability and Cross-Context Predictive Validity of Temperament in Infant Rhesus Macaques

Temperament refers to individual differences in emotional, motor, and attentional responsiveness that persist throughout development. In rhesus macaques ( Macaca mulatta ), temperament has been evaluated using the Infant Behavioral Assessment Scale (IBAS), a behavioral assessment of temperament and neurological development within the first month of life; and the BioBehavioral Assessment (BBA), a battery of standardized tests of behavioral, cognitive, and physiological evaluations, administered at 3-4 months of age. It is currently unclear how these two temperament assessments relate to one another. Here, we used linear effect models to examine whether IBAS constructs predict conceptually similar BBA constructs in infant rhesus macaques. Results show that none of the predicted constructs were associated. These findings suggest that early-life behavioral tendencies assessed by the IBAS may not directly map onto later-emerging temperament dimensions captured by the BBA, pointing to potential issues with construct validity or the temporal stability of early infant temperament in macaques.