Convergence of multiple sources of information on infant individuality: neonatal behavior,infant behavior,and temperament reports

To shed light on the notion of enduring individual infant characteristics, convergence of three presumably interrelated measures of infant individuality was examined. Data collected included standardized behavioral assessments of the newborn (NBAS), maternal reports of infant temperament (at 3 and 9 months), and naturalistic observations of infant behavior at 1, 3, and 9 months. Infant temperament reports were significantly stable from 3 to 9 months; observed infant fussiness was significantly stable from 1 to 3 and 3 to 9 months; observed altertness/social responsiveness was not stable over time. Analyses of convergence of neonatal and infant behavior revealed that 9-month infant alertness/social responsiveness was significantly correlated with neonatal habituation. Similar analyses of neonatal behavior and reported temperament revealed that 3-month reported dullness was significantly correlated with neonatal habituation and range of state. At 9 months, temperament ratings of infant fussiness and unpredictability were significantly correlated with autonomic stability; fussiness was also significantly correlated with regulation of state. Finally, no significant relationships were observed between reported temperament and observed infant behavior. These results fail to support a simple notion of enduring individuality in infants over their first year of life.