David Haley
Department of Psychology
University of Toronto at Scarborough

The role of early experience in infant stress physiology.

Infant stress physiology provides a window into the way the brain functions in relation to social and cognitive development. Stress physiology affects how we learn, and even how we learn to regulate the stress system. The dialectical interplay between stress physiology and learning partly reflects social and biological feedback mechanisms that have evolved to help organisms survive; these mechanisms require some training or fine tuning during the course of early development. In this talk, I present research that addresses three questions that relate to the development of stress physiology and its role in learning and memory in low- and high-risk infants. The first is how the environment affects the development of the stress system. Substantial work, primarily with animals, indicates that early experience permanently alters the development of the stress system, a process that is fashionably referred to as "programming." I provide some new evidence to support this perspective in human infants. The second question I consider is how infants learn to regulate the stress system. Here I argue that infants learn to regulate their stress in part by reacting to and recovering from momentary failures in the parent-infant relationship. I also consider the links between individual differences in parenting style and infant stress regulation. The role the stress system plays in learning and memory is the focus of my final question. I build on developmental and neurobiological theories of learning and memory and present new evidence that the capacity to regulate stress physiology plays an important role in contingency learning and memory in infancy. I conclude with a discussion of future directions.