Melanie Soderstrom

The prosodic bootstrapping of phrases: Evidence from prelinguistic infants

Abstract The current study explores infants’ use of prosodic cues coincident with phrases in processing fluent speech. After familiarization with two versions of the same word sequence, both 6- and 9-month-olds showed a preference for a passage containing the sequence as a noun phrase over a passage with the same sequence as a syntactic non-unit. However, this result was found only in one of the two groups, the group exposed to a stronger prosodic difference between the syntactic and non-syntactic sequences. Six month olds were tested in the same way on passages containing verb phrases. In this case, both groups preferred the passage with the verb phrase to the passage with the same word sequence as a syntactic non-unit. These results provide the first evidence that infants as young as 6 months old are sensitive to prosodic markers of syntactic units smaller than the clause, and, in addition, that they use this sensitivity to recognize phrasal units, both noun and verb phrases, in fluent speech. This ability to use phrase-level prosodic cues is variable, however, and appears to depend on the strength or number of cues associated with these syntactic units.

When Do Caregivers Talk? The Influences of Activity and Time of Day on Caregiver Speech and Child Vocalizations in Two Childcare Environments

The importance of the language environment in influencing language outcomes is well known, but few studies have addressed the contextual factors that influence the amount of speech heard and vocalizations produced by a young child under naturalistic conditions. We analyze effects of type of activity engaged in by the child and time of day on quantitative measures of the language environment. We found effects of both activity and time of day. Structured activities generated the highest levels of adult language, but not necessarily the most child vocalizations. Home and daycare environments looked overall very similar on these measures, however there were important differences across the two environments with respect to the specific effects of activity and time of day.

(Baby)Talk to Me The Social Context of Infant-Directed Speech and Its Effects on Early Language Acquisition

Since the mid-20th century, scientists have observed unique features in speech, facial expression, and content directed to infants and toddlers in comparison to speech directed to adults. Whereas much research has studied the characteristics of so-called infant-directed speech and speculated about its significance for language learning, research directly testing these ideas has been more limited until recently. Studies now suggest that infant-directed speech (a) promotes infant attention to language, (b) fosters social interaction between infants and caregivers, and (c) informs infants about various aspects of their native language by heightening distinctions relative to the speech addressed to adults. New developments focusing on the social role of infant-directed conversational interactions highlight the importance of caregiver responsiveness to the infant. Building a communicative foundation even prior to the time language emerges is crucial for fostering language development.

Predicting individual variation in language from infant speech perception measures

There are increasing reports that individual variation in behavioral and neurophysiological measures of infant speech processing predicts later language outcomes, and specifically concurrent or subsequent vocabulary size. If such findings are held up under scrutiny, they could both illuminate theoretical models of language development and contribute to the prediction of communicative disorders. A qualitative, systematic review of this emergent literature illustrated the variety of approaches that have been used and highlighted some conceptual problems regarding the measurements. A quantitative analysis of the same data established that the bivariate relation was significant, with correlations of similar strength to those found for well-established nonlinguistic predictors of language. Further exploration of infant speech perception predictors, particularly from a methodological perspective, is recommended.

The learner as statistician: three principles of computational success in language acquisition

© 2009 The Authors. Journal compilation

Early perception–late comprehension of grammar? The case of verbal - s : a response to de Villiers & Johnson (2007)

Two recent papers (de Villiers & Johnson, 2007; Johnson, de Villiers & Seymour, 2005) have claimed that children have difficulty with verbal -s until five-six-years-old. This contrasts with perceptual studies showing evidence for sensitivity to the grammatical properties of verbal -s as young as 1; 4. These apparently conflicting findings can be reconciled by differentiating between early perceptual grammatical knowledge and later semantic comprehension.

What Do North American Babies Hear? A large-scale cross-corpus analysis

A range of demographic variables influences how much speech young children hear. However, because studies have used vastly different sampling methods, quantitative comparison of interlocking demographic effects has been nearly impossible, across or within studies. We harnessed a unique collection of existing naturalistic, day-long recordings from 61 homes across four North American cities to examine language input as a function of age, gender, and maternal education. We analyzed adult speech heard by 3- to 20-month-olds who wore audio recorders for an entire day. We annotated speaker gender and speech register (child-directed or adult-directed) for 10,861 utterances from female and male adults in these recordings. Examining age, gender, and maternal education collectively in this ecologically valid dataset, we find several key results. First, the speaker gender imbalance in the input is striking: children heard 2-3× more speech from females than males. Second, children in higher-maternal education homes heard more child-directed speech than those in lower-maternal education homes. Finally, our analyses revealed a previously unreported effect: the proportion of child-directed speech in the input increases with age, due to a decrease in adult-directed speech with age. This large-scale analysis is an important step forward in collectively examining demographic variables that influence early development, made possible by pooled, comparable, day-long recordings of childrens language environments. The audio recordings, annotations, and annotation software are readily available for reuse and reanalysis by other researchers.

Temporal characteristics of child-directed speech

Child-directed speech (CDS) is produced with a slower tempo compared to adult-directed speech (ADS). Yet the characterization of CDS as simply slowly spoken speech masks a number of underlying subtleties. We investigated temporal characteristics of CDS as a function of speech register based on a highly controlled set of elicited data. six sentence forms containing five monosyllabic words were read several times in declarative and question intonation with three focus conditions in CDS and ADS. After an evaluation of the data through a perceptual rating task, 2301 sentences produced by one mother and five theater students were segmented at the word-level using forced-alignment tools (Yuan and Liberman, 2008). We found strong effects of the CDS register on duration across the entire sentence. Additionally, elongation in CDS applied even to the syllables without an explicit focal accent and to function words. Our data also demonstrated a highly consistent ratio of the final syllable to the sentence duration b...

Influences of number of adults and adult: child ratios on the quantity of adult language input across childcare settings

New approaches to examining the language environment are putting greater emphasis on the use of highly naturalistic audio recordings and questions about cross-cultural differences in children’s real-world language experiences. These new approaches and questions require careful examination of different kinds of variables that may influence children’s language experiences. The current study examines the influence of the number of adults and adult:child ratio on the number of words heard by young children across three childcare settings (home, home daycare and daycare centre). The home setting was characterized by a high number of one-on-one interactions, while children in daycare centres were exposed to larger numbers of adults present. While a linear relationship was found between the number/ratio of adults and words heard in the home setting, these relationships were more complex in daycare centres, and no relationships were found in home daycares.