Preschoolers’ vocabulary acquisition sets the stage for later reading ability and school achievement. This study examined the role of socioeconomic status (SES) and the quality of the home environment of seventy-seven Chilean majority and Mapuche minority families from low and lower-middle-class backgrounds in explaining individual differences in vocabulary acquisition of their three-and-a-half-year-old children. Additionally, we investigated whether the relation between SES and receptive and expressive vocabulary was mediated by the quality of the home environment as the Family Investment Model suggests. The quality of the home environment significantly predicted receptive and expressive vocabulary above and beyond ethnicity, SES, parental caregiver status, and quantity of daycare. Furthermore, the quality of the home environment mediated the relation between SES and expressive and receptive vocabulary acquisition.

Speech disfluencies can guide the ways in which listeners interpret spoken language. Here, we examined whether three-year-olds, five-year-olds, and adults use filled pauses to anticipate that a speaker is likely to refer to a novel object. Across three experiments, participants were presented with pairs of novel and familiar objects and heard a speaker refer to one of the objects using a fluent (“Look at the ball/lep!”) or disfluent (“Look at thee uh ball/lep!”) expression. The salience of the speaker's unfamiliarity with the novel referents, and the way in which the speaker referred to the novel referents (i.e., a noun vs. a description) varied across experiments. Three- and five-year-olds successfully identified familiar and novel targets, but only adults’ looking patterns reflected increased looks to novel objects in the presence of a disfluency. Together, these findings demonstrate that adults, but not young children, use filled pauses to anticipate reference to novel objects.

Production studies show connective acquisition by age 3;0, but comprehension studies show errors until 9;0 or older. To further investigate this gap, two comprehension tasks were carried out with 78 Dutch children between the ages of 7;0 and 10;1, testing contrastive maar ‘but’ and causal want ‘because’ connectives for comparison. An existing context choice task and a task that tested children's ability to interpret pronouns dependent on the connective were used. Children did well on the context choice task for want ‘because’, but performed far below chance with maar ‘but’. In the pronoun interpretation task the youngest children performed at or near chance with both connectives, but show gradual improvement with age. Task complexity may partially explain the results but in general, they are consistent with previous experiments showing contrastive connective comprehension is acquired very late compared to their correct production. Further, the pronoun interpretation task may give a more accurate picture of understanding.

Four- and five-year-old children took part in an elicited familiar and novel Lithuanian noun production task to test predictions of input-based accounts of the acquisition of inflectional morphology. Two major findings emerged. First, as predicted by input-based accounts, correct production rates were correlated with the input frequency of the target form, and with the phonological neighbourhood density of the noun. Second, the error patterns were not compatible with the systematic substitution of target forms by either (a) the most frequent form of that noun or (b) a single morphosyntactic default form, as might be predicted by naive versions of a constructivist and generativist account, respectively. Rather, most errors reflected near-miss substitutions of singular for plural, masculine for feminine, or nominative/accusative for a less frequent case. Together, these findings provide support for an input-based approach to morphological acquisition, but are not adequately explained by any single account in its current form.

This study investigates whether the earliest words children choose to say are mainly words containing sounds they can produce (cf. ‘phonological dominance’ hypotheses), or whether children choose words without regard to their phonological characteristics (cf. ‘lexical dominance’ hypotheses). Phonological properties of words in spontaneous speech from six children age 0;8 to 2;11 were analyzed by comparing sound distributions of consonant place and manner. Word-initial and word-final consonant patterns in children's Word Targets versus Actual Word Forms were analyzed as a function of vocabulary size. Word-initial results showed more overall evidence for phonological dominance. In word-final position, at lower vocabulary sizes, results showed several differences between Word Targets and Actual Word Forms, consistent with lexical dominance. These findings challenge an ‘either–or’ phonological versus lexical dominance approach, and support consideration of a multifactorial set of influences, including different phonological dimensions and word positions, on the words that young children choose to say.

Children pay more attention to the beginnings and ends of sentences rather than the middle. In natural speech, ends of sentences are prosodically and segmentally enhanced; they are also privileged by sensory and recall advantages. We contrasted whether acoustic enhancement or sensory and recall-related advantages are necessary and sufficient for the salience of grammatical morphemes at the ends of sentences. We measured 22-month-olds’ listening times to grammatical and ungrammatical sentences with third person singular -s. Crucially, by cross-splicing the speech stimuli, acoustic enhancement and sensory and recall advantages were fully crossed. Only children presented with the verb in sentence-final position, a position with sensory and recall advantages, distinguished between the grammatical and ungrammatical sentences. Thus, sensory and recall advantages alone were necessary and sufficient to make grammatical morphemes at ends of sentences salient. These general processing constraints privilege ends of sentences over middles, regardless of the acoustic enhancement.

The goal of this study was to determine if typically developing children could form grammatical categories from distributional information alone. Twenty-seven children aged six to nine listened to an artificial grammar which contained strategic gaps in its distribution. At test, we compared how children rated novel sentences that fit the grammar to sentences that were ungrammatical. Sentences could be distinguished only through the formation of categories of words with shared distributional properties. Children's ratings revealed that they could discriminate grammatical and ungrammatical sentences. These data lend support to the hypothesis that distributional learning is a potential mechanism for learning grammatical categories in a first language.

Asking children to clarify themselves promotes their ability to uniquely identify objects in referential communication tasks. However, little is known about whether parents ask preschoolers for clarification during interactions and, if so, how. Study 1 explored how mothers clarify their preschoolers’ ambiguous descriptions of the characters in their narratives, and whether clarification requests affect children's repairs of their ambiguous descriptions. Mothers were found to use different strategies, including signaling misunderstanding and modeling appropriate descriptions. Presence of these different strategies predicted children's ability to provide informative repairs. Study 2 tested the effect of children's experience with signaling misunderstanding and modeling on their ability to uniquely identify the characters of a story on a second narration. Experiencing modeling, but not misunderstandings, positively affected children's provision of appropriate descriptions during second narrations. Findings are discussed in terms of the role of imitation in driving referential development.

The positive effects of shared book reading on vocabulary and reading development are well attested (e.g., Bus, van Ijzendoorn, & Pellegrini, 1995). However, the role of shared book reading in grammatical development remains unclear. In this study, we conducted a construction-based analysis of caregivers’ child-directed speech during shared book reading and toy play and compared the grammatical profile of the child-directed speech generated during the two activities. The findings indicate that (a) the child-directed speech generated by shared book reading contains significantly more grammatically rich constructions than child-directed speech generated by toy play, and (b) the grammatical profile of the book itself affects the grammatical profile of the child-directed speech generated by shared book reading.

This paper reports the preliminary results of a study examining the role of structural overlap, language exposure, and language use on cross-linguistic influence (CLI) in bilingual first language acquisition. We focus on the longitudinal development of determiners in a corpus of two French–English children between the ages of 2;4 and 3;7. The results display bi-directional CLI in the rate of development, i.e., accelerated development in English and a minor delay in French. Unidirectional CLI from English to French was instead observed in the significantly higher rate of ungrammatical determiner omissions in plural and generic contexts than in singular specific contexts in French. These findings suggest that other language-internal mechanisms may be at play. They also lend support to the role of expressive abilities on the magnitude of this phenomenon.

Rhotics, particularly the trill, are late acquired sounds in Spanish. Reports of Spanish–English bilingual preschoolers document age-appropriate articulations, but studies do not explore productions once exposure to English increases. This paper reports on the rhotic productions of a cross-sectional sample of 31 Spanish–English bilingual children, ages 6;8 to 13;5. Children produced taps with high rates of accuracy across age groups; the trill did not reach 80% target production until age 11;3, later than reported for monolingual speakers. Increased English exposure is explored as a contributing factor, arguing a need for continued study of bilingual phonological development beyond the preschool years.

Social feedback is a driving force for speech development. A recent study provided a key finding to explain how contingent responses influence developmental change: infant speech-related vocalizations are contingent on responses to prior speech-related vocalizations (Warlaumont et al., 2014). However, the study did not distinguish between different speech-related vocalizations, vowel-like (V) and consonant–vowel (CV) vocalizations, which is important because CV vocalizations are a precursor to words. The present study explored parents’ responses to infants’ vocalizations and infants’ subsequent vocal production at a point when vocalizations become more like adult speech. The relative proportion of CVs following contingent responses to CV did not differ between 10- and 12-months-olds; however, there was only a significant contingent relationship between responses to CV and subsequent CV production in 12-month-olds. Results suggest a developmental transition and a social feedback loop for the production of more developmentally advanced sounds when infants are learning their first words.