How the characteristics of words in child-directed speech differ from adult-directed speech to influence children’s productive vocabularies

Abstract

Child-directed speech has long been known to influence children’s vocabulary learning. However, while we know that caregiver utterances differ from those directed at adults in various ways, little is known about any differences in the lexical properties of child-directed and adult-directed utterances. We compare over half a million word tokens from adult speech directed at children (from caregiver–child transcriptions) to the same quantity directed at adults. We show that child-directed speech contains greater numbers of words that are lower in phonemic length, higher in frequency, lower in phonotactic probability, and higher in neighborhood density than adult-directed speech; furthermore, child-directed speech explains over twice the variability of children’s productive noun vocabularies than adult-directed speech. These findings indicate that children’s word production is clearly influenced by the characteristics of the words spoken directly to them and that researchers need to be wary of using adult-directed language corpora when calculating lexical measures.

CLASSIC Utterance Boundary: A Chunking‐Based Model of Early Naturalistic Word Segmentation

“…This is in line with recent work showing that frequent words are more likely to share phonological material with previously learned words, therefore boosting child learning compared to learning less frequent words (Jones et al, 2023). Our result was also in line with evidence showing an effect of overlapping phonological sequences on vocabulary learning at around 2 years of age (e.g., Jones et al, 2023;Stokes, 2010;Storkel, 2009) but no effect at 12-15 months (Swingley & Humphrey, 2018), suggesting that children first build a diverse repertoire of phonological chunks that later boost word learning (for a computational test of this idea using CLASSIC, see Jones & Rowland, 2017).…”

“…Finally, to support our claim regarding the role of overlapping phonological sequences in CLASSIC-UB, we conducted an additional exploratory analysis showing that CLASSIC-UB's ability to better approximate children's vocabulary in word length and neighborhood density increased as word frequency increased (see Appendix S12 in the Supporting Information online.). This is in line with recent work showing that frequent words are more likely to share phonological material with previously learned words, therefore boosting child learning compared to learning less frequent words (Jones et al, 2023). Our result was also in line with evidence showing an effect of overlapping phonological sequences on vocabulary learning at around 2 years of age (e.g., Jones et al, 2023;Stokes, 2010;Storkel, 2009) but no effect at 12-15 months (Swingley & Humphrey, 2018), suggesting that children first build a diverse repertoire of phonological chunks that later boost word learning (for a computational test of this idea using CLASSIC, see Jones & Rowland, 2017).…”

Linking acoustic variability in the infants' input to their early word production

“…We also found that higher frequency words that were produced in CDS more often were predicted to be produced earlier than higher frequency words produced in CDS less often. This effect of CDS is consistent with research showing that acoustic properties of mother's speech in CDS predict vocabulary growth between 18 and 24 months (Han, De Jong, & Kager, 2023), and suggests that in addition to drawing infants' attention to speech (as evidenced by infant's overall preference for CDS; Cooper and Aslin (1990); ManyBabies Consortium ( 2020)), CDS also shapes children's word learning on a word-by-word basis (see also Jones, Cabiddu, Barrett, Castro, and Lee (2023)). Further, the robust effect of CDS for high frequency words suggests that the benefits of CDS might stem from frequent repetitions (Schwab & Lew-Williams, 2016), though future research will need to more explicitly test this hypothesis.…”

Parent–toddler play talk: Toddler speech is differentially associated with paternal and maternal speech in interaction

“…Early vocabulary is a robust predictor of later academic and social success (Bleses et al, 2016) and as linguistic input plays a key role in vocabulary acquisition (Jones et al, 2023), it is important to identify any source of influence in the input. The words children produce are influenced by the words spoken directly to them (Jones et al, 2023) thus with the increased availability of fathers to their children, at least in this socio-demographic context, it is important to profile fathers' CDS as resource for the child.…”

“…Early vocabulary is a robust predictor of later academic and social success (Bleses et al, 2016) and as linguistic input plays a key role in vocabulary acquisition (Jones et al, 2023), it is important to identify any source of influence in the input. The words children produce are influenced by the words spoken directly to them (Jones et al, 2023) thus with the increased availability of fathers to their children, at least in this socio-demographic context, it is important to profile fathers' CDS as resource for the child. Our findings suggest that children may be exposed to different lexical sets by different conversational partners, namely mother and father, and points to the added value for the child of engaging in separate dyadic interactions with both mother and father.…”