NEWBORN BEHAVIOR AND TEMPERAMENT

By Jennifer T. Liske and I. Simona Bujoreanu

The question of the nature and stability of individual differences among infants and their influence on later personality are issues that have serious implications for practice in the field of infant mental health. One clear demonstration of preservation comes from the research of Kagan and Snidman, which shows that, controlling for social class and ethnicity, high compared with low reactivity at four months of age predicts, to a significant degree, the profiles of shy, withdrawn, sociable and bold behavior patterns, later in childhood and adolescence (Kagan and Snidman, 1991). High versus low reactivity at four months of age predicts to a significant degree, the profiles of shy, withdrawn, sociable and bold behavior patterns, later in childhood and adolescence. Observations of 4-month-old infants exposed to visual, auditory, and olfactory stimulation point to the possible biological bases for the inhibited and uninhibited profiles of behavior. These behavioral profiles, defined by a combination of motor arousal and crying, are predictive of inhibited and uninhibited behavior profiles in infants up to 12 years of age. However, little is known about the early behavioral signs in the period prior to four months that might predict high or low reactivity at four months.

The goal of the ongoing study (The relationship between newborn behavior and temperament is to see if these behavioral patterns can be identified in the newborn period, and if there is a relationship between newborn behavioral characteristics and temperament categories at 4 months of age. One hundred healthy full-term newborns were assessed on the second day of life with a new revised standardized behavioral scale, based on the Neonatal Behavioral Assessment Scale (Brazelton and Nugent, 1995). This standardized presentation leaves less chance for human variation in the stimuli presentation, provides a more objective set of newborn behavior observations, and produces standard scores for newborn behavior in the immediate postpartum period up to two months of age. At four months of age, the participants were examined with a temperament battery (Kagan et al.) measuring behavioral and physiological responses (cardiac function, and EEG power and asymmetry).

Chi-square analysis of the first 41 infants reveal a significant relation between newborn crying and soothability measures and patterns and high/low reactive temperament categories at four months (p< .05). For instance, newborns that cried a great deal and were difficult to console were more likely to be classified as high reactive infants at four months of life, while newborns who cried minimally and were easy to console, were more likely to be classified as low reactive infants at four month of age (see attached Table 1). The stability of these profiles suggests that some babies are born with a high threshold for excitability and others with a low level of reactivity. Analysis of the total sample (n=100) will be presented to further examine the degree to which these newborn differences persist over time.

By generating performance norms for healthy full term infants evaluated with the revised scale, this is the first study using newborn standard scores to measure individual differences. The study is contributing to the debate of stability of individual behavioral patterns by using outcome categories of known predictive validity based on direct behavioral observations and not on parental report. The results of the study will help professionals and parents understand and support infant’s temperament and behaviors, by designing an environment in which the infant’s development can thrive.

Table 1. Classification of infants at newborn and at four months.

x²(2) = 11.0, p < .05

This study is conducted by J. Kevin Nugent, Ph.D., Jerome Kagan, Ph.D., Nancy Snidman, Ph.D., Jennifer T. Liske, MA, and I. Simona Bujoreanu, MA.