This study analyzes how others engage rural and urban Mozambican infants during naturalistic observations, and how the proportion of time spent in different engagements relates to infants' language development over the second year of life. Using an extended version of Bakeman and Adamson's (1984) categorization of infant engagement, we investigated to what extent a detailed analysis of infant engagement can contribute to our understanding of vocabulary development in natural settings. In addition, we explored how the different infant engagements relate to vocabulary size, and how these differ between the two communities. Results show that rural infants spend significantly more time in forms of solitary engagement, whereas urban infants spend more time in forms of triadic joint engagement. In regard to correlations with reported productive vocabulary, we find that dyadic persons engagement (i.e. interactions not about concrete objects) has positive correlations with vocabulary measures in both rural and urban communities. In addition, we find that triadic coordinated joint attention has a positive relationship with vocabulary in the urban community, but a contrasting negative correlation with vocabulary in the rural community. These similarities and differences are explained, based upon the parenting beliefs and socialization practices of different prototypical learning environments. Overall, this study concludes that the extended categorization provides a valuable contribution to the analysis of infant engagement and their relation to language acquisition, especially for analyzing naturalistic observations as compared to semi-structured studies. Moreover, with respect to vocabulary development, Mozambican infants appear to benefit strongest from dyadic Persons engagement, while they do not necessarily benefit from joint attention, as tends to be the case for children from industrial, developed communities.

English has a word-minimality requirement that all open-class lexical items must contain at least two moras of structure, forming a bimoraic foot (Hayes, 1995).Thus, a word with either a long vowel, or a short vowel and a coda consonant, satisfies this requirement. This raises the question of when and how young children might learn this language-specific constraint, and if they would use coda consonants earlier and more reliably after short vowels compared to long vowels. To evaluate this possibility we conducted an elicited imitation experiment with 15 two-year-old Australian English-speaking children, using both perceptual and acoustic analysis. As predicted, the children produced codas more often when preceded by short vowels. The findings suggest that English-speaking two-year-olds are sensitive to language-specific lexical constraints, and are more likely to use coda consonants when prosodically required.

Caregiver speech is not a static collection of utterances, but occurs in conversational exchanges, in which caregiver and child dynamically influence each other's speech. We investigate (a) whether children and caregivers modulate the prosody of their speech as a function of their interlocutor's speech, and (b) the influence of the initiator of the conversation on durational characteristics of the exchange. We analyzed naturalistic conversations from 13 mother–infant/toddler dyads aged 12–30 months across full-day recordings of 3–5 days per dyad using LENA and automated analytic tools. We found small, but significant, effects of mothers and their children influencing each other's speech, particularly in pitch measures. We also found longer utterances and shorter response latencies for the initiator of a conversation. While mothers show more mature conversational capabilities (more entrainment, shorter response latencies), our findings converge with prior research to highlight the active role of young children in the conversational exchange.

This study investigates the role of acoustic salience and hearing impairment in learning phonologically minimal pairs. Picture-matching and object-matching tasks were used to investigate the learning of consonant and vowel minimal pairs in five- to six-year-old deaf children with a cochlear implant (CI), and children of the same age with normal hearing (NH). In both tasks, the CI children showed clear difficulties with learning minimal pairs. The NH children also showed some difficulties, however, particularly in the picture-matching task. Vowel minimal pairs were learned more successfully than consonant minimal pairs, particularly in the object-matching task. These results suggest that the ability to encode phonetic detail in novel words is not fully developed at age six and is affected by task demands and acoustic salience. CI children experience persistent difficulties with accurately mapping sound contrasts to novel meanings, but seem to benefit from the relative acoustic salience of vowel sounds.

The current study investigated school-aged children's internalization of the distributional patterns of English lexical stress as a function of vocabulary size. Sixty children (5;3 to 8;3) participated in the study. The children were asked to blend two individually presented, equally stressed syllables to produce disyllabic nonwords with different resulting structures in one of two frame sentences. The frame sentences were designed to elicit either a noun or verb interpretation of the nonword. Children's receptive vocabulary was also assessed. The results indicated that children more readily blended syllable pairs that resulted in trochaic-compatible word structures than in iambic-compatible structures. This effect was strongest in young children with large vocabularies. As for stress placement, all children were sensitive to the effect of word structure, but only children with the largest vocabularies were sensitive to the biasing effect of grammatical category (noun = trochee; verb = iamb). The study results are discussed with reference to the observation that speech motor skills develop in tandem with lexical acquisition and the hypothesis that phonological knowledge emerges in part from abstraction across lexical representations.

We designed a parent-directed home-visiting intervention targeting socioeconomic status (SES) disparities in children's early language environments. A randomized controlled trial was used to evaluate whether the intervention improved parents' knowledge of child language development and increased the amount and diversity of parent talk. Twenty-three mother–child dyads (12 experimental, 11 control, aged 1;5–3;0) participated in eight weekly hour-long home-visits. In the experimental group, but not the control group, parent knowledge of language development increased significantly one week and four months after the intervention. In lab-based observations, parent word types and tokens and child word types increased significantly one week, but not four months, post-intervention. In home-based observations, adult word tokens, conversational turn counts, and child vocalization counts increased significantly during the intervention, but not post-intervention. The results demonstrate the malleability of child-directed language behaviors and knowledge of child language development among low-SES parents.

Past research suggests that bilingualism positively affects children's performance in false belief tasks. However, researchers have yet to fully explore factors that are related to better performance in these tasks within bilingual groups. The current study includes an assessment of proficiency in both languages (which was lacking in past work) and investigates the relationship between proficiency and performance in a variety of mental state tasks (not just false belief). Furthermore, it explores whether the relationship between language proficiency and performance in mental state tasks differs between bilingual and monolingual groups. Twenty-six Spanish–English bilingual and twenty-six English monolingual preschool-age children completed seven mental state tasks. Findings provide evidence that high proficiency in English is related to better performance in mental state tasks for monolinguals. In contrast, high proficiency in both English and Spanish is related to better performance in mental state tasks for bilinguals.

This paper investigates whether three-year-olds are able to process attributive adjectives (e.g., soft pillow) as they hear them and to predict the noun (pillow) on the basis of the adjective meaning (soft). This was investigated in an experiment by means of the Visual World Paradigm. The participants saw two pictures (e.g., a pillow and a book) and heard adjective–noun combinations, where the adjective was either informative (e.g., soft) or uninformative (e.g., new) about the head-noun. The properties described by the target adjectives were not visually apparent. When the adjective was uninformative, the looks at the target increased only upon hearing the noun. When the adjective was informative, however, the looks at the target increased upon hearing the adjective. Three-year-olds were as fast as adult controls in predicting the upcoming noun. We conclude that toddlers process adjective–noun phrases incrementally and can predict the noun based on the prenominal adjective.

This study investigates the development of metalinguistic skills, particularly ambiguity detection, and whether training accelerates this development for prereaders in kindergarten (5;5–6;6). It is the first to compare homophone detection with lexically ambiguous sentence detection in which the same homophones appear. The experimental group received ambiguity detection training; the control group received vocabulary training. Results showed that there is a spontaneous development of homophone detection abilities at the end of kindergarten, and training may accelerate this trajectory. The development of lexical ambiguity detection is not apparent in kindergarteners. However, explicit training improves this trajectory significantly. The knowledge of both meanings of a homophone is not sufficient to report both meanings of a sentence that contains that homophone. We propose that detecting the dual meanings of an ambiguous sentence involves sentence processing operations and an ability to think flexibly about language that may be enhanced with training.

This study is about the role of elicited verbal imitation in toddler word learning. Forty-eight toddlers were taught eight nonwords linked to referents. During training, they were asked to imitate the nonwords. Naming of the referents was tested at three intervals (one minute later [uncued], five minutes, and 1–7 days later [cued]) and recognition at the last two intervals. Receptive vocabulary, nonword repetition, and expressive phonology were assessed. The accuracy of elicited imitation during training predicted naming at one and five minutes, but not 1–7 days later. Neither nonword repetition nor expressive phonology was associated with naming over time but extant vocabulary predicted performance at all time intervals. We hypothesize that elicited imitation facilitates word learning in its earliest stages by supporting encoding of the word form into memory and allowing practice of the articulatory-phonological plan. At later stages, vocabulary facilitates integration of the word form into the lexical network.