Effects Of Familiarity And Feeding On Newborn Speech-Voice Recognition

Newborn infants preferentially orient to familiar over unfamiliar speech sounds. They are also better at remembering unfamiliar speech sounds for short periods of time if learning and retention occur after a feed than before. It is unknown whether short-term memory for speech is enhanced when the sound is familiar (versus unfamiliar) and, if so, whether the effect is further enhanced by feeding. We used a two-factorial design and randomized infants to one of four groups: prefeed-unfamiliar, prefeed-familiar, postfeed-unfamiliar, and postfeed-familiar. Memory for either familiar or unfamiliar speech (the infant's mother saying baby versus a female stranger saying beagle) was assessed using head turning to sound in an habituation-recovery paradigm and a retention delay of 85sec either before or after a typical milk feed. Memory for the familiar speech-voice was enhanced relative to the unfamiliar speech-voice, expressed by significantly less head turning toward the habituated sound stimulus when it was re-presented after the delay. Memory for familiar or unfamiliar speech was not significantly enhanced from pre- to postfeeding, nor was there a significant interaction. This is the first demonstration in newborns that familiarity enhances short-term memory for speech-voice sound.