The present study investigated the relationship between paternal involvement and the speech fathers use with their infants, as well as, how experience with paternal speech affects patterns of brain activity to male speech for 6-month-olds. Both mothers and fathers alter their speech when talking to an infant relative to when they talk to an adult. This special speech register is called infant-directed speech (IDS) and is characterized by slower tempo, higher and more variable pitch, repetition, and simplified vocabulary. It was hypothesized that more involved fathers would use IDS to a greater degree than fathers who were less involved in caregiving. It was also expected that infants’ brain activity to male speech would differ based on experience with paternal IDS.

Data were collected in two sessions. In the first session, mother-infant and father-infant interactions were recorded and analyzed to provide a descriptive account of parents' use of IDS, along with measures of parental involvement. Shortly after this session, infants' brain activity was recorded while they listened to familiar words in four conditions: male IDS, male ADS, female IDS, and female ADS. The findings revealed that paternal involvement was related to the amount of IDS fathers used but not the moderation of the acoustic characteristics of IDS, such as pitch. Moreover, infants' patterns of brain activity to male IDS were related to both paternal involvement in caregiving and fathers' use of IDS in the interactions. Overall, this study furthers our understanding of the unique contributions fathers' make to children's cognitive development and the ways infants’ early experiences shape their neural development.