Roughly 10-20% Caucasian children are shy and hesitant in unfamiliar situations. Another 10-20% are sociable and intrepid in response to novelty. The underlying features of these predispositions usually referred to as “temperament”, remain remarkably consistent over time. It has also been found that the caregiving environment in the early years can significantly influence the behaviors characteristic of these temperaments. That makes the study of temperament particularly relevant to this blog.
Nancy Snidman, a colleague of the pioneer researcher in temperament, defines temperament as a “predisposition to respond to the environment in certain ways” (lecture to UMB IPMHPCP, March 6, 2016). The baby comes into the world with certain temperamental qualities. These temperamental qualities may be due to genetics or epigenetics – influences from the environment in the womb. Children’s temperament influences the way they react to their environment – physical, social, and emotional. For example, a child’s temperament affects the way they react to novelty, sensory stimulation, or transitions. How does temperament at infancy translate to temperamental characteristics such as shyness in a preschool child? What does the “shy” infant look like as an older child or adult? Snidman and Kagan did a series of longitudinal studies to try to answer these questions.
Kagan and Snidman studied 400, 4-month old babies and classified them as high reactive (HR) and low reactive (LR) on the basis of their response to auditory, visual, and olfactory stimuli. They observed the babies’ responses in the form of heart rate increase, motor arousal (such as limb flexion and extension, motor tension, and back arch) and fretting or crying. They looked for the extremes of HR and LR babies and started to follow them.
They postulated that the HR children had inherited a low threshold of excitability in the amygdala; a part of the mid-brain called the limbic system, and the related limbic areas. The amygdala sends signals to the autonomic nervous system, communicating a sense of threat in the environment.
They studied the babies’ physiology and behavior in response to a number of laboratory procedures, from 9 months to 15 years. Some of these procedures were mild, such as puppets or tasting sweet and sour liquids, and some were more challenging, such as a toy robot and a stranger approaching wearing a lab coat and a gas mask. The two extreme styles of temperament, HR or LR, or behaviorally inhibited (BI) – shy, wary of novelty, slow to approach, or behaviorally uninhibited (BU) – sociable, comfortable with novelty, were remarkably consistent over the years.
Interestingly, the researchers found that as the kids got older the physiological markers were more important than the behavioral ones. This was because the children were taught to be polite. It was less the general behavior to strangers that distinguished the HR from the LR kids, and more the smiles and spontaneous comments. When children are presented with the same stimuli in repeated exposures, for example when they are shown invalid pictures (a horse head on a fish body), they usually habituate to the stimulus. That means their reaction becomes smaller with repeated exposures. In the case of HR kids, however, there is no habituation! That means that although they look more and more like their LR peers in terms of social behavior, their heart rate, pupillary dilatation, muscle tension, and stress hormones remain more reactive.
This is very interesting to me in my work with children and families. For more than two decades, Attachment Theory has dominated research in child psychology. This way of understanding child development minimizes the contribution of temperament. Yet, I have found temperament a very useful way of making sense of some of the problems that parents bring to me regarding their children’s behavior. It is also helpful to me when I consult to preschool teachers. In the next blog posting I will describe how I use ideas of temperament to help parents and teachers understand the children in their care.
Schwartz C, Snidman N, Kagan J (1999). Adolescent social anxiety as an outcome of inhibited temperament in childhood, JAACAP 38(8):1008-1015.
Kagan J (1997) Temperament and the reactions to unfamiliarity, Child Development 68(1):139-143.
Kagan J (1989). Temperamental contributions to social behavior, American Psychologist 44(4):668-674.