How does maternal odor influence socioemotional processing in infancy?

Humans are born as social beings. Especially during the first months of life, the mother plays a pivotal role for the survival and wellbeing of an infant. It is a commonly accepted truism that the mother's body odor can have a strong impact on an infant's behavior, helping to calm and soothe an infant. From a scientific perspective, however, olfaction as a means of social communication has been sorely neglected, especially when it comes to human development. The present project will take a first step in filling this gap. We will investigate the influence of maternal odor on social perception in human infants, focusing in particular on the processing of emotional information. During the initial period of this project, we were able to find first evidence pointing to a link between the processing of maternal odor and emotion processing in infancy: event-related brain potentials (ERPs) suggest that 7-month-old infants allocate more attention to positive information in the presence of maternal odor, while no attentional enhancement was observed in the control group. During the extension period, we seek to corroborate these data and extend them to a broader perspective of maternal odor in social processing in infancy. Three electroencephalographic (EEG) studies will be conducted in healthy 7-month-old infants, each investigating a different aspect of the link between maternal odor and social processing. In each study, infants will be randomly assigned to one of three experimental groups: Infants will either perform the experiment in the presence of maternal odor carried by a t-shirt previously worn by the infant's mother (experimental); infants will be exposed to an identical but unworn t-shirt (control 1); or infants will be exposed to a t-shirt previously worn by a different mother to investigate specificity for the infant's own mother (control 2). The first EEG study will investigate the impact of maternal odor on unconscious emotion processing. The second study will go beyond emotion processing and focus on social yet non-emotional perception, specifically the processing of facial trustworthiness. The third study will directly contrast the processing of social and non-social information. All analyses will focus on differences in the event-related potential, reliably observable in infants. Based on results from the initial study, we expect an increased response to positive information in the presence of maternal odor compared to the control groups. In sum, this project addresses the potency of a heavily understudied modality, namely olfaction, to modulate social perception. The project thus has implications beyond the field of developmental psychology, and will further our understanding of a healthy mother-infant relationship.