Abstract
Previous research has found that infants respond with more negative/protest as well as approach-type behaviors in response to the loss of maternal attention to a social-rival as compared to a non-social item. The purpose of the current research was to conceptually replicate the maternal inattention research with a different population and to extend on it by examining the relationships between infants' emotional responses and their temperament and physiology (brain activity). A baseline measure of infant EEG was collected after which mother–infant dyads (n = 30) participated in two mother-ignoring conditions. Infants demonstrated more approach-style responses (maternal-directed gaze, proximity, and touch), higher reactivity levels (increased arousal, aggression, and disorganization), and more negative affect in the social-rival relative to the nonsocial condition. Approach-style (jealousy) responses were predictive of the infants' greater left frontal baseline EEG activity. Maternal reports of an infant's temperamental sociability and approach were not related to frontal EEG but several temperamental characteristics were associated with approach style responses during the social-rival condition. These findings collectively point to the emotion of jealousy in infants, as only during the social rival condition were associations between approach style responses and negative affect as well as left frontal EEG activity uncovered.