Assessing receptive verb knowledge in late talkers and autistic children: advances and cautionary tales.

PURPOSE: Using eye-tracking, we assessed the receptive verb vocabularies of age-matched late talkers and typically developing children (experiment 1) and autistic preschoolers (experiment 2). We evaluated how many verbs participants knew and how quickly they processed the linguistic prompt. Our goal is to explore how these eye-gaze measures can be operationalized to capture verb knowledge in late talkers and autistic children. METHOD: Participants previewed two dynamic scenes side-by-side (e.g., "stretching" and "clapping") and were then prompted to find the target verb's referent. Children's eye-gaze behaviors were operationalized using established approaches in the field with modifications in consideration for the type of stimuli (dynamic scenes versus static images) and the populations included. Accuracy was calculated as a proportion of time spent looking to the target, and linguistic processing was operationalized as latency of children's first look to the target. RESULTS: In experiment 1, there were no group differences in the proportion of verbs known, but late talkers required longer to demonstrate their knowledge than typically developing children. Latency was predicted by age but not language abilities. In experiment 2, autistic children's accuracy and latency were both predicted by receptive language abilities. CONCLUSION: Eye gaze can be used to assess receptive verb vocabulary in a variety of populations, but in operationalizing gaze behavior, we must account for between- and within-group differences. Bootstrapped cluster-permutation analysis is one way to create individualized measures of children's gaze behavior, but more research is warranted using an individual differences approach with this type of analysis.

Two pathways in vocabulary development: Large-scale differences in noun and verb semantic structure.

In adults, nouns and verbs have varied and multilevel semantic interrelationships. In children, evidence suggests that nouns and verbs also have semantic interrelationships, though the timing of the emergence of these relationships and their precise impact on later noun and verb learning are not clear. In this work, we ask whether noun and verb semantic knowledge in 16-30-month-old children tend to be semantically isolated from one another or semantically interacting from the onset of vocabulary development. Early word learning patterns were quantified using network science. We measured the semantic network structure for nouns and verbs in 3,804 16-30-month-old children at several levels of granularity using a large, open dataset of vocabulary checklist data. In a cross-sectional approach in Experiment 1, early nouns and verbs exhibited stronger network relationships with other nouns and verbs than expected across multiple network levels. Using a longitudinal approach in Experiment 2, we examined patterns of normative vocabulary development over time. Initial noun and verb learning was supported by strong semantic connections to other nouns, whereas later-learned words exhibited strong connections to verbs. Overall, these two experiments suggest that nouns and verbs demonstrate early semantic interactions and that these interactions impact later word learning. Early verb and noun learning is affected by the emergence of noun and verb semantic networks during early lexical development.

Assessing receptive verb knowledge in late talkers and autistic children: Advances and cautionary tales.

Purpose: Using eye-tracking, we assessed the receptive verb vocabularies of late talkers and typically developing children (Experiment 1) and autistic preschoolers (Experiment 2). We evaluated how many verbs participants knew and how quickly they processed the linguistic prompt. Method: Participants previewed two dynamic scenes side-by-side (e.g., "stretching" and "clapping") and were then prompted to find the target verb. Children's eye gaze behaviors were operationalized using established approaches in the field with modifications in consideration for the type of stimuli (dynamic scenes versus static images) and the populations included. Accuracy was calculated as a proportion of time spent looking to the target, and linguistic processing was operationalized as latency of children's first look to the target. Results: In Experiment 1, there were no group differences in the proportion of verbs known, but late talkers required longer to demonstrate their knowledge than typically developing children. Latency was predicted by age but not language abilities. In Experiment 2, autistic children's accuracy and latency were both predicted by receptive language abilities. Conclusion: Eye gaze can be used to assess receptive verb vocabulary in a variety of populations, but in operationalizing gaze behavior, we must account for between- and within-group differences. Bootstrapped cluster-permutation analysis is one way to create individualized measures of children's gaze behavior, but more research is warranted using an individual differences approach with this type of analysis. Finally, latency may not be a valid measure for dynamic scene stimuli for children under three years old.

Can Retrieval Practice Facilitate Verb Learning in Children With Developmental Language Disorder and Their Peers With Typical Language Development?

PURPOSE: Children with developmental language disorder (DLD) have well-documented verb learning difficulties. In this study, we asked whether the inclusion of retrieval practice during the learning period would facilitate these children's verb learning relative to a similar procedure that provided no retrieval opportunities. METHOD: Eleven children with DLD (M age = 60.09 months) and 12 children with typical language development (TD; M age = 59.92 months) learned four novel verbs in a repeated spaced retrieval (RSR) condition and four novel verbs in a repeated study (RS) condition. The words in the two conditions were heard an equal number of times, in the context of video-recorded actors performing novel actions. RESULTS: Recall testing immediately after the learning period and 1 week later revealed greater recall for novel verbs in the RSR condition than for novel verbs in the RS condition. This was true for both groups, and for immediate as well as 1-week testing. The RSR advantage remained when children had to recall the novel verbs while watching new actors perform the novel actions. However, when tested in contexts requiring the children to inflect the novel verbs with -ing for the first time, the children with DLD were much less likely to do so than their peers with TD. Even words in the RSR condition were only inconsistently inflected. CONCLUSIONS: Retrieval practice provides benefits to verb learning-an important finding given the challenges that verbs present to children with DLD. However, these benefits do not appear to automatically translate to the process of adding inflections to newly learned verbs but rather appear to be limited to the operations of learning the verbs' phonetic forms and mapping these forms onto associated actions.

Difference or delay? Syntax, semantics, and verb vocabulary development in typically developing and late-talking toddlers.

While semantic and syntactic properties of verb meaning can impact the success of verb learning at a single age, developmental changes in how these factors influence acquisition are largely unexplored. We ask whether the impact of syntactic and semantic properties on verb vocabulary development varies with age and language ability for toddlers aged 16 to 30 months in a large sample (N = 5520, N Late Talkers = 821; N Typically Developing = 4699, cutoff = 15th percentile) of vocabulary checklist data from the MacArthur- Bates Communicative Development Inventory (MBCDI). Verbs from the MBCDI were coded for their syntactic and semantic properties, including manner/result meanings, durative/punctual events, and syntactic complexity. Both late talkers and typically developing children were less likely to produce syntactically complex verbs at younger ages as compared to older ages. Group differences emerged for manner/result: Typically developing children were more likely to produce manner verbs at all ages, but late talkers were more likely to produce result verbs. Regardless of group, children who produced more manner versus result verbs also had larger verb vocabulary sizes overall. These results suggest that late talkers and typically developing toddlers differ in how they build their verb vocabularies.

Repetition Versus Variability in Verb Learning: Sometimes Less Is More.

Purpose This study examined whether 2-year-olds are better able to acquire novel verb meanings when they appear in varying linguistic contexts, including both content nouns and pronouns, as compared to when the contexts are consistent, including only content nouns. Additionally, differences between typically developing toddlers and late talkers were explored. Method Forty-seven English-acquiring 2-year-olds (n = 14 late talkers, n = 33 typically developing) saw scenes of actors manipulating objects. These actions were labeled with novel verbs. In the varied condition, children heard sentences containing both content nouns and pronouns (e.g., "The girl is ziffing the truck. She is ziffing it!"). In the consistent condition, children heard the verb an equal number of times, but only with content nouns (e.g., "The girl is ziffing the truck. The girl is ziffing the truck!"). At test, children were shown two new scenes and were asked to find the novel verb's referent. Children's eye gaze was analyzed as a measure of learning. Results Mixed-effects regression analyses revealed that children looked more toward the correct scene in the consistent condition than the varied condition. This difference was more pronounced for late talkers than for typically developing children. Conclusion To acquire an initial representation of a new verb's meaning, children, particularly late talkers, benefit more from hearing the verb in consistent linguistic contexts than in varying contexts.

The syntactic and semantic features of two-year-olds' verb vocabularies: a comparison of typically developing children and late talkers.

Children with language disorders have particular difficulty with verbs, but when this difficulty emerges is unknown. We examined syntactic (transitive, intransitive, ditransitive) and semantic (manner, result) features of two-year-olds' verb vocabularies, contrasting late talkers and typically developing children to look for early differences in verb vocabulary. We conducted a retrospective analysis of parent-reported expressive vocabulary from the Language Development Survey (N = 564, N(LT) = 62) (Rescorla, 1989). Verbs were coded for the presence or absence of each syntactic and semantic feature. Binomial mixed-effects regressions revealed the effect of feature on children's knowledge and whether feature interacted with group classification. Our results revealed mostly similarities between late talkers and typically developing children. All children's vocabularies showed a bias against verbs that occur in ditransitive frames. One feature showed a difference between groups: late talkers showed a bias against manner verbs that typically developing children did not.

Optimal Contexts for Verb Learning.

Purpose: Verb learning is a critical but challenging part of language acquisition. Children with or at increased risk for developmental language disorder (DLD) may particularly struggle with verb learning, and poor verb representations in turn may negatively impact children's language outcomes. Our goal is to examine literature on children's acquisition of verbs, identifying manipulable factors that may determine the ease or difficulty of acquiring a new verb meaning. Method: In this narrative, non-systematic review, we discuss findings about how verbs are learned and represented. Results: Several aspects of the learning environment affect children's efforts to acquire verbs, including the linguistic context in which the verb is introduced, the timing of the linguistic label relative to the event it describes, visual and linguistic variability, and dose frequency. Conclusions: We conclude that some learning situations are likely to be more helpful for children in the process of verb learning than others. We highlight some of the factors that contribute to good learning situations, and we discuss how these may differ depending on properties of the child and of the verb itself. Finally, we propose hypotheses for future translational and clinical research.

Acquisition of Verb Meaning From Syntactic Distribution in Preschoolers With Autism Spectrum Disorder.

Purpose: Our goal was to investigate whether preschool children with autism spectrum disorder (ASD) can begin to learn new word meanings by attending to the linguistic contexts in which they occur, even in the absence of visual or social context. We focused on verbs because of their importance for subsequent language development. Method: Thirty-two children with ASD, ages 2;1-4;5 (years;months), participated in a verb-learning task. In a between-subjects design, they were randomly assigned to hear novel verbs in either transitive or intransitive syntactic frames while watching an unrelated silent animation or playing quietly with a toy. In an eye-tracking test, they viewed two video scenes, one depicting a causative event (e.g., boy spinning girl) and the other depicting synchronous events (e.g., boy and girl waving). They were prompted to find the referents of the novel verbs, and their eye gaze was measured. Results: Like typically developing children in prior work, children with ASD who had heard the verbs in transitive syntactic frames preferred to look to the causative scene as compared to children who had heard intransitive frames. Conclusions: This finding replicates and extends prior work on verb learning in children with ASD by demonstrating that they can attend to a novel verb's syntactic distribution absent relevant visual or social context, and they can use this information to assign the novel verb an appropriate meaning. We discuss points for future research, including examining individual differences that may impact success and contrasting social and nonsocial word-learning tasks directly.