The Role of Early Experience

*Boston Children's Hospital- Division of Developmental Medicine, Laboratories of Cognitive Neuroscience

Several recent studies have demonstrated that infants show different behavioral and brain responses when viewing their mother's face as compared to viewing a stranger's face (Barrera & Maurer, 1981; de Haan & Nelson, 1999). However, the reason for why this occurs is still unknown. Potentially, these differences are caused by the emotional salience attributed to Mom compared to a stranger, through infants' extensive interactions with her. In contrast, these differences in behavior and brain activity could be due to the relative familiarity of Mom compared to a stranger - most infants see Mom's face far more often than any other face.

In order to distinguish between these two possibilities, infants are divided into two groups. Parents of the "experience" group are given a realistic 3D model of a woman's face to keep in their homes starting when their babies are 2 months old. The 3D models have neutral facial expressions and do not move, so that emotional salience is likely not attributed to them. After 1 month of experience with the 3D models, the infants are brought in to our lab and event-related potentials (ERPs) are recorded while they view pictures of the familiar face and an unfamiliar face. Parents of the "no-experience" group bring their infants into our lab after they are already 3 months old and are familiarized to one of the 3D models for a short period of time. We then record ERPs while they view pictures of the familiar face and an unfamiliar face, similar to the "experience" group.

The overall goal of this study is to determine how these different kinds of experiences affect infants' processing of familiar and unfamiliar faces. Therefore, we will examine how ERP components that are sensitive to novelty and familiarity differ across the two groups of infants.