LINGUIST List 2.398

Saturday, 10 August 1991

Disc: Manual Babbling: A Response from Petitto

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Message 1: Manual Babbling

Date: Fri, 09 Aug 91 16:27:09 EDT
From: INLO000 <INLO%MUSICB.MCGILL.CAVM1.MCGILL.CA>
Subject: Manual Babbling
To: Linguist Members Several requests for further information about a recent study of manual babbling have been forwarded to me. The reference is... Petitto, L.A. and Marentette, P.F. (1991) Babbling in the manual mode: Evidence for the ontogeny of language. Science, vol 251, pp. 1493-1496. (1) Re: Babbling in X, where X is any language. As can be seen from the title, this study is not about babbling IN any signed language, per se. As with spoken languages, infants (esp. in the early period) do not babble in specific signed languages. (2) Re: Vocal babbling in deaf children. Studies of the vocal productions of profoundly deaf infants have demonstrated that previous researchers' claims (e.g., Lenneberg) about the existence of vocal babbling in deaf infants were unfounded. While I will limit my comments here to syllabic babbling (definition below), my comments are true of the other vocalizations that are produced by deaf infants; that is, there are qualitative differences between hearing and profoundly deaf infants' vocalizations throughout early development. Although profoundly deaf infants may occasionally produce a well-formed syllabic vocalization, these forms are (1) infrequent relative to their other vocalizations, and (2) occur in unsystematic ways. Indeed, only those deaf children who can benefit from the use of hearing aids (i.e., they have some hearing) will produce syllabic babbling, but, here, too, other significant developmental anomalies characterize their babbling due to the absence of audition (e.g., Oller). However, deaf infants acquiring a natural signed language from birth, freely produce manual babbling on the identical time course and sequence observed for vocal babbling. (Both hearing infants acquiring a signed language, and bilingual hearing infants acquiring a spoken and a signed language, also achieve all linguistic milestones (e.g., babbling, first words, first combinations) within the same time period commonly observed in human language acquisition (see Petitto & Marentette for all relevant references.) Interestingly, hearing infants will occasionally produce well-formed syllabic manual babbling. As with deaf infants' vocal babbling, the hearing infants' manual babbling is (i) infrequent relative to their other manual productions, and (ii) occurs in unsystematic ways. In the Petitto & Marentette paper I offer an explanation for the existence of this phenomenon in hearing and deaf infants. Below is my response to another question that I received from a member of Linguist; he suggested that my answer may be of interest to other members of Linguist. Re: What do people NOW call what used to be called BABBLING? There is still controversy over definitions, per se. However, I think there would be general agreement regarding the following very ROUGH characterization: Babbling is the general term used to refer to the class of meaningless, but linguistically-related vocal (or manual) productions by children, which typically occurs both prior to and during early language development (more below). There is still controversy over whether children's early babbling inventories comprise a universal set of phonetic forms and controversy over WHY this may/may not be the case; there is still controversy over whether babbling is continuous with later later development, and the extent to which babbling is language-specific. My own studies of vocal and manual babbling support the following conclusions: babbling is a maturationally controlled, specifically-linguistic phenomenon. As in the literature, the single term babbling is used to refer to the following different, but related phenomena over time (the following is not intended to reflect strict stages, per se): In the early months, depending upon the modality of the language input, infants (4-7 months) produce a restricted set of phonetic forms (vocally, if exposed to spoken languages and manually if exposed to signed languages); the forms of infants acquiring spoken languages appear to be drawn from the set of possible sounds found in spoken languages and are typically not language-specific; the identical phenomenon is observed in children (hearing or deaf) who are acquiring signed languages. As such, the initial inventory of forms common to infants' acquiring spoken languages and infants acquiring signed languages (respectively) can be overlapping, although infants do exhibit individual form preferences. Around 7-9 months, infants begin the production of syllabic (reduplicated or canonical) babbling (e.g., Oller), for example, dadada, bababa. The child is still not producing actual words in her target language at this time; nonetheless, these forms obey the prosodic and phonological lawfulness (e.g., Stampe) of human Language. Syllabic (vocal or signed) babbling is characterized by (1) use of a reduced subset of possible sounds (phonetic units) found in language, (ii) syllabic organization (well-formed consonant-vowel clusters), and (iii) use without apparent meaning or reference; there are several other properties (e.g., see Petitto & Marentette for relevant references and other properties). Around ages 9-12 months, I have observed (like de Boysen-Bardies) that aspects of the child's babbling forms can take on language-specific characteristics, a phenomenon that I have observed in four different languages (2 spoken, 2 signed). Moreover, there is a continuity of phonetic form and syllabic type within an individual child's syllabic babbling and their first words. Around 12-14 months (and beyond in some children), hearing and deaf children produce jargon babbling (meaningless babbling sequences that maintain the timing, rhythm and duration of spoken and signed sentences, respectively). Jargon babbling can and typically does continue even during hearing and deaf children's production of first words and signs (respectively). Representational structures: I believe only one explanation of human language ontogeny fully accounts for these and other similarities in the time course and content of signed and spoken language acquisition: Humans are born with a predisposition to discover particular sized units with particular distributional patterns in the input, guided by innately-specified structural constraints. At birth, this nascent structure-seeking capacity is sensitive to the patterned organization of natural language phonology common to all world languages, be they spoken or signed (e.g., rhythmic, temporal, and hierarchical organization) and is particularly sensitive to structures in the input that correspond to the size and distributional patterns of the syllable in spoken and signed languages. --This is a mouthful. For relevant references and further explication, see Petitto, in press, and Petitto & Marentette, 1991. *** I'd be happy to send people reprints. Just send me your address. Laura Ann Petitto