Emotional Contagion is defined as the unconscious converging of one�s emotional state with another, suggesting that one can �catch� the emotions of another through vocal expressions, postures, and facial expressions (Hatfield et al., 1993). This phenomenon can be observed in adulthood, but also in infancy as early as the first 24 hours following birth. While negative emotional contagion has been studied in the form of contagious crying at various ages of infancy, positive emotional contagion has received very little attention. The purpose of the present study was to observe the emotional reactions of forty-five infants at 5 and 10 months of age when they were presented with a stimulus of their peers displaying facial expressions and making vocalizations of positive affect. It was hypothesized that infants would react to the stimuli of positive emotions with expressions of positive affect and/or vocalizations of laughter. Additionally, it was hypothesized that the intensity and duration of both the expressions and the vocalizations would increase with age between assessments at 5 and 10 months. Due to the fact that this study was exploratory in nature, predictions of the outcome were based on infants� emotional responses to distress in contagious crying studies as well as the typical developmental timeline of positive emotions.Psycholog
