Neonate Orientation Behaviour towards Human Voice

Abstract

Head, eye, mouth and crying responses were recorded in one-six day old neonates in an experimental (N = 36) and in a control condition (N = 12). In the experimental con-dition, the babies were sitting in a chair surrounded by a uniform white curtain and exposed to playback of a male voice transmitted successively through three loud-speakers at the left, the right or in front of the chair, according to a factorial design. In the control condition, there was no voice. The voice enhanced head movements, opening of the eyes, mouthing and crying and it influenced hand-sucking. The babies' head behavior can be described as positive orientation since first head movements after the voice had started to talk were most frequently given in the direction of the source of the sound. A possible explanation of the data on eye behaviour and on crying is that the babies turned their head towards the voice because they expected to see something else than a uniform white curtain by doing this. Their eyes were more frequently open when they first turned their head in the direction of the source than when they turned in the opposite direction. The onset of crying took place most frequently when the babies were facing the source and was more frequent when their preceding head movement had lead to an approach than when it had not. Individual differences between certain variables of the babies' behaviour can be related to type of feeding. Breast-fed babies showed positive mouth orientation when the voice came from the right and from the left of the chair, whereas bottle-fed babies mainly mouthed towards the left whatever the source of the sound. The possibility that the babies behaved, as far as the mouth was concerned, according to rules established during feeding, is discussed. Other differences between breast-and bottle-fed babies were found for hand-sucking and crying.