The Influence of Mouthing on Infant Vocalization

Abstract

Although vocalization and mouthing are behaviors frequently performed by infants, little is known about the characteristics of vocalizations that occur with objects, hands, or fingers in infants' mouths. The purpose of this research was to investigate characteristics of vocalizations associated with mouthing in 6-to 9-month-old infants during play with a primary caregiver. Results suggest that mouthing may influence the phonetic characteristics of vocalizations by introducing vocal tract closure and variation in consonant production.Mouthing, defined as contact of an object with the mouth, lips, or tongue (Rochat, 1989;Ruff, Saltarelli, Capozzoli, & Dubiner, 1992), is a common behavior during infancy (Belsky & Most, 1981;Fenson, Kagan, Kearsley, & Zelazo, 1976;Kopp, 1976). In a study of 7.5− to 21-month-old infants (Belsky & Most, 1981), all 40 infants displayed mouthing behavior during play with toys between 7.5 and 13.5 months. In addition to its prominence across infants, mouthing is a regularly occurring behavior both in terms of number of occurrences and duration of episodes (Kopp, 1976;Ruff, 1984;Whyte, McDonald, Baillargeon, & Newell, 1994).Studies of mouthing have not typically examined vocalizations associated with episodes of mouthing. Moreover, studies of mouthing often focus on the mouthing of objects, less frequently investigating contact of the hands and fingers with infants' mouths. Elbers (1982), however, noted that between ages 6 and 12 months her son vocalized with the back of one hand against his mouth and while holding his fingers in his mouth. She interpreted both activities as variants in bringing about vocal tract closure and constriction. In an additional study of 4 infants between 6 and 11 months, Ejiri and Masataka (2001) documented both the frequent occurrence of mouthing and co-occurrences of mouthing and vocalization; however, they did not describe the characteristics of co-occurring vocalizations. Descriptions of vocalizations that co-occur with mouthing may be important for three reasons: Mouthing is an exploratory behavior that may extend to encompass exploration of co-occurring vocalizations; the peak period of mouthing behavior in infancy coincides with and may contribute to advances in consonant production; and mouthing, which appears to contribute to the development of multimodal object perception, may also contribute to the development of multimodal speech perception. Mouthing and ExplorationStudies documenting the exploratory nature of object-related mouthing have consistently shown that infants use mouthing as a means to explore object characteristics and discover what they afford for action (Fenson et al., 1976;Rochat, 1989;Ruff et al., 1992). Moreover, infants vary their approach to exploration to maximize the information they obtain (e.g., scratching objects to obtain information about their affordance for noise; Rochat, 1989) and exploit affordances differentially (e.g., fingering textured objects and mouthing patterned objects). The exploratory nature of mouth...

Object exploration at 6 and 9 months in infants with and without risk for autism

“…The production of CV syllables is perhaps the most important language milestone of the first year, and delayed emergence of CV syllables is a reliable predictor of later language delay (Oller et al, 1998). Fagan and Iverson (2007) found that relative to vocalizations unaccompanied by object mouthing, vocalizations produced while infants were mouthing objects were more likely to contain a CV syllable and to contain a greater variety of consonant sounds. They suggested that object mouthing provided infants with opportunities to explore vocal production when the vocal tract was partially blocked (as it is during consonant production).…”

Atypical object exploration in infants at-risk for autism during the first year of lifer

“…Specifically, object exploration abilities are directly related to the development of cognitive skills such as object knowledge (Caruso, 1993; Bourgeois et al, 2005), non-verbal, and verbal communication skills such as the use of gestures and words within a social context (Fagan and Iverson, 2007; Iverson and Wozniak, 2007), as well as social skills such as imitation, joint attention, and pretend play (Bruckner and Yoder, 2007; McDuffie et al, 2012). Promoting object interactions within a social context will enhance multisystem development of infants at-risk for developing ASD.…”

“…In fact three weeks of enhanced postural training led to improved reaching, mouthing, and fingering of objects in 2- to 5-month-old TD infants (Lobo and Galloway, 2008). Moreover, object exploration skills have implications for other forms of development such as perceptual (Needham, 2000; Bhat and Galloway, 2006; Lobo and Galloway, 2008; Koterba et al, 2012), social communication (Meltzoff, 1995; Fagan and Iverson, 2007; Iverson et al, 2007), and cognitive development (Caruso, 1993; Bourgeois et al, 2005; Fontenelle et al, 2007). In terms of perceptual development, infants learn various object properties such as texture, shape, size, color, and sound while exploring objects (Ruff, 1984, 1986; Palmer, 1989; Rochat, 1989).…”

“…Specifically, infants who spent majority of their time exploring objects were more successful and used different strategies to retrieve the toy from the container (Caruso, 1993). Lastly, object play promotes both non-verbal communication skills such as showing and pointing (Iverson and Goldin-Meadow, 2005) as well as verbal communication skills such as vocalizations produced while exploring objects (Fagan and Iverson, 2007; Iverson et al, 2007) and labeling of objects (Baldwin and Markman, 1989). Specifically, rhythmic shaking of the rattle was closely related to babble onset in 4- to 9-month-old infants (Iverson et al, 2007) and mouthing of objects was closely associated with consonant production in 6- to 9-month-olds (Fagan and Iverson, 2007).…”

Articulating What Infants Attune to in Native Speech

“…One study found that 6–9-month-olds produce more frequent and more varied supra-glottal consonants (i.e., made with lips or tongue) during play interactions with their primary caregiver, if they vocalize while mouthing an object or their fingers/hand (contact with mouth, lips or tongue) than if they are not mouthing an object. The authors concluded that active oral engagement with objects introduces and enhances variations in vocal tract closures (i.e., consonantal gestures) during social play vocalizations, due to the increased multimodal information provided by mouthing and vocalizing simultaneously, which encourages exploration of consonant production (Fagan & Iverson, 2007). This interpretation may extend to understanding the bias toward posterior consonant imitation by younger infants.…”