Thai has imperfective aspectual morphemes that are not obligatory in usage, whereas English has obligatory grammaticized imperfective aspectual marking on the verb. Furthermore, Thai has verb final deictic-path verbs that form a closed class set. The current study investigated if obligatoriness of these grammatical categories in Thai and English affects the expression of co-occurring temporal events and actions depicted in three different short animations. Ten children aged four years, five years, six years and seven years, and ten adults as a comparison group from each of the two languages participated. English speakers explicitly expressed the ongoingness of the events more than Thai speakers, whereas Thai speakers expressed the entrance and exit of protagonists depicted in the animations significantly more than English speakers. These results support the notion that obligatory grammatical categories shape how Thai and English speakers express temporal events or actions.

This commentary concerns two issues: the contribution of connectionism and theories of learning to developmental psychology; and the status of connectionist models of syntax acquisition.

Since there are no systematic pauses delimiting words in speech, the problem of word segmentation is formidable even for monolingual infants. We use computational modeling to assess whether word segmentation is substantially harder in a bilingual than a monolingual setting. Seven algorithms representing different cognitive approaches to segmentation are applied to transcriptions of naturalistic input to young children, carefully processed to generate perfectly matched monolingual and bilingual corpora. We vary the overlap in phonology and lexicon experienced by modeling exposure to languages that are more similar (Catalan and Spanish) or more different (English and Spanish). We find that the greatest variation in performance is due to different segmentation algorithms and the second greatest to language, with bilingualism having effects that are smaller than both algorithm and language effects. Implications of these computational results for experimental and modeling approaches to language acquisition are discussed.

From early on, infants show a preference for infant-directed speech (IDS) over adult-directed speech (ADS), and exposure to IDS has been correlated with language outcome measures such as vocabulary. The present multi-laboratory study explores this issue by investigating whether there is a link between early preference for IDS and later vocabulary size. Infants’ preference for IDS was tested as part of the ManyBabies 1 project, and follow-up CDI data were collected from a subsample of this dataset at 18 and 24 months. A total of 341 (18 months) and 327 (24 months) infants were tested across 21 laboratories. In neither preregistered analyses with North American and UK English, nor exploratory analyses with a larger sample did we find evidence for a relation between IDS preference and later vocabulary. We discuss implications of this finding in light of recent work suggesting that IDS preference measured in the laboratory has low test-retest reliability.

Mean Length of Utterance (MLU) has been widely used to measure children’s early language development in a variety of languages. This study investigates the utility of MLU to measure language development in four agglutinative and morphologically complex Southern Bantu languages. Using a variant of MLU, MLU3, based on the three longest sentences children produced, we analysed the utterances of 448 toddlers (16-32 months) collected using the MacArthur-Bates Communicative Development Inventory, a parent-report tool. MLU3, measured in words (MLU3-w) and morphemes (MLU3-m), significantly correlated with age and other indices of language growth (e.g., grammar and vocabulary). MLU3 measures also accounted for significant variance in language development particular morphosyntactic development. Our results suggest that MLU3-m is a more sensitive measure than MLU3-w. We conclude that MLU measured in morphemes provides a useful addition to other indices of language development in these kinds of morphologically complex languages.

The present study tested Huttenlocher & Weiner's (1971) hypothesis concerning the role of grammatical function in sentence comprehension. Children arranged objects to correspond to descriptions of transitive relations in two tasks. The patterns of object placements provided evidence of how children understood the various sentence forms. Contrary to Huttenlocher & Weiner's hypothesis, grammatical function was not a critical factor in object placements. This was true based on the group data or individual-based analyses. Two factors were important: logical function and order of mention of the items in the sentence. Whether an item was grammatical subject or grammatical object did not affect subjects' choices. The order of mention effects resulted from inattention to sentence meaning prior to the initial choices on certain trials. If the logical relations in a sentence were understood prior to the response, only logical function influenced subjects' responses.

In Lebanese Arabic, lexical subjects may occur before or after verbs, but only before non-verbal predicates. Analysis of spontaneous language samples from 19 two-year-old children shows that postverbal (VS) and preverbal (SV) subjects emerge simultaneously. The youngest children displayed no VS-SV difference in frequency. A slight preference for SV is observed in older children. No preference for SV subjects was found in the speech of the mothers of the younger or older children. Lexical subjects systematically appeared before non-verbal predicates. We interpret these results as evidence for early knowledge of syntactic movement, consistent with Wexler’s (1998) Very Early Parameter Setting.

This study examined the acquisition of numeral classifiers in 120 monolingual Japanese children. Previous research has argued that the complex semantic system underlying classifiers is late acquired. Thus, we set out to determine the age at which Japanese children are able to extend the semantic properties of classifiers to novel items/situations. Participants completed a comprehension task with a mouse-tracking extension and a production task with nonce and familiar items. While the comprehension results showed ceiling effects on familiar and nonce items, age significantly modulated a difference in accuracy between familiar and nonce items in the production task. The findings suggest that the acquisition of the underlying semantic system is acquired much earlier than previously argued. Previously attested issues with Japanese classifier production in young(er) children are more likely to reflect accessing difficulties than indexing the underlying grammatical competence of the classifier system.

Adolescent pregnancy can impact the educational attainment of adolescent mothers and language development of their children. However, support services and interventions can mitigate these risk factors. Adolescent mothers have shown success in implementing various language facilitation strategies (LFS) with their children when coached. We developed a triadic language intervention in a facilitated playgroup context to support adolescent mothers’ use of language strategies when interacting with their children. The current pilot study utilized a pre-test, post-test descriptive approach to analyze differences in adolescent mothers’ language use and parenting behaviors and their children’s language use after participation in facilitated playgroups. All adolescent mothers demonstrated enhanced parenting practices. Changes in mothers’ and children’s language from pre- to post-test were variable across participants. While this pilot study shows promising evidence of the utility of a triadic intervention situated in playgroups with adolescent families, further research is required to address the limitations of this study.

Young children today are exposed to masks on a regular basis. However, there is limited empirical evidence on how masks may affect word learning. The study explored the effect of masks on infants’ abilities to fast-map and generalize new words. Seventy-two Chinese infants (43 males, Mage = 18.26 months) were taught two novel word-object pairs by a speaker with or without a mask. They then heard the words and had to visually identify the correct objects and also generalize words to a different speaker and objects from the same category. Eye-tracking results indicate that infants looked longer at the target regardless of whether a speaker wore a mask. They also looked longer at the speaker’s eyes than at the mouth only when words were taught through a mask. Thus, fast-mapping and generalization occur in both masked and not masked conditions as infants can flexibly access different visual cues during word-learning.

This paper reports on an original study designed to investigate age-related change in the way French children produce speech during oral narrative, considering both prosodic parameters – speaking rate and duration of the prosodic speech unit – and linguistic structure. Eighty-five French children aged four to eleven years were asked to tell a story after they were shown an excerpt from an animated film. All their remarks were transcribed and coded using ELAN as an annotation tool. Each narrative was analyzed for duration, articulation rate, and linguistic components (i.e., number of phonic groups, syllables, words, clauses). All measures were found to increase with age, with the duration of the phonic group and its linguistic structure showing the stronger differences. Results contribute to providing reference data on speech production during childhood, and they suggest the existence of two distinct developmental patterns in narrative production.