Infant Voice and Mouth Movements Affect Adult Attributions

Abstract

How are adults able to engage in prolonged "conversations" with preverbal infants? Without language, how does the infant hold the adult's conversational attention? Past studies by the author found that features of the preverbal infant's voice affect adult impressions. In the presentstudies it was hypothesized that specific features of the infant's face during vocalization account for adult social perceptions. In Experiment 1, a videotape of 24 thirty-second segments of 3-month-old, vocalizing infants was presented to three groups of adults. Twelve infants in the tape produced 'speech-like" syllabic sounds, and 12 infants produced, nasalized vocalic sounds. The conditions of tape presentation differed for the groups: AI V (audiovisual), Audio only, Video only. Adults rated infants on characteristics of social favorability and communicative intent. All groupsgave higher ratings to syllabic infants independently of modality of presentation. Therefore, visual, as well as, auditory cues to syllabic vocalization affected adult reactions. It was hypothesized in Experiment2 that mouth movement was the visual cue that influenced the adults' more favorable impressions of syllabic vocalizations. A videotape of 16 thirty-second segments was presented to three groups (A/V, Audio, Video) of adults. In this tape, 4 of the infants were shown moving their mouths and 4 were shown with no mouth movements. The 3-month-olds were randomly presented twice, and syllabic and vocalic sounds were dubbed onto the video track so that infants served as their own control for sound category. In the absence of audio cues (Video-only group), adult ratings were influenced by the infants' mouth movements. Taken together these experiments indicate that adults use features of speech (sound quality, mouth movements) in forming impressions of the infant as a social and communicative partner.