Learning verbs in English and Korean: The roles of word order and argument drop.

To learn new words, particularly verbs, child learners have been shown to benefit from the linguistic contexts in which the words appear. However, cross-linguistic differences affect how this process unfolds. One previous study found that children's abilities to learn a new verb differed across Korean and English as a function of the sentence in which the verb occurred (Arunachalam et al., 2013). The authors hypothesized that the properties of word order and argument drop, which vary systematically in these two languages, were driving the differences. In the current study, we pursued this finding to ask if the difference persists later in development, or if children acquiring different languages come to appear more similar as their linguistic knowledge and learning capacities increase. Preschool-aged monolingual English learners (N = 80) and monolingual Korean learners (N = 64) were presented with novel verbs in contexts that varied in word order and argument drop and accompanying visual stimuli. We assessed their learning by measuring accuracy in a forced-choice pointing task, and we measured eye gaze during the learning phase as an indicator of the processes by which they mapped the novel verbs to meaning. Unlike previous studies which identified differences between English and Korean learning 2-year-olds in a similar task, our results revealed similarities between the two language groups with these older preschoolers. We interpret our results as evidence that over the course of early childhood, children become adept at learning from a larger variety of contexts, such that differences between learners of different languages are attenuated.

Pupils Dilate More to Harder Vocabulary Words than Easier Ones.

Understanding cognitive effort expended during assessments is essential to improving efficiency, accuracy, and accessibility within these assessments. Pupil dilation is commonly used as a psychophysiological measure of cognitive effort, yet research on its relationship with effort expended specifically during language processing is limited. The present study adds to and expands on this literature by investigating the relationships among pupil dilation, trial difficulty, and accuracy during a vocabulary test. Participants (n = 63, Mage = 19.25) completed a subset of trials from the Peabody Picture Vocabulary Test while seated at an eye-tracker monitor. During each trial, four colored images were presented on the monitor while a word was presented via audio recording. Participants verbally indicated which image they thought represented the target word. Words were categorized into Easy, Medium, and Hard difficulty. Pupil dilation during the Medium and Hard trials was significantly greater than during the Easy trials, though the Medium and Hard trials did not significantly differ from each other. Pupil dilation in comparison to trial accuracy presented a more complex pattern, with comparisons between accurate and inaccurate trials differing depending on the timing of the stimulus presentation. These results present further evidence that pupil dilation increases with cognitive effort associated with vocabulary tests, providing insights that could help refine vocabulary assessments and other related tests of language processing.

Spoken verb learning in children with language disorder.

The current study examined spoken verb learning in elementary school children with language disorder (LD). We aimed to replicate verb learning deficits reported in younger children with LD and to examine whether verb instrumentality, a semantic factor reflecting whether an action requires an instrument (e.g., "to chop" is an instrumental verb), influenced verb learning. The possible facilitating effect of orthographic cues presented during training was also evaluated. In an exploratory analysis, we investigated whether language and reading skills mediated verb learning performance. General language skills and verb learning were assessed in Dutch children with LD and age-matched typically developing controls (n = 25 per group) aged 8 to 12 years (M = 9;9 [years;months], SD = 1;3). Using video animations, children learned 20 nonwords depicting actions comprising 10 instrumental and 10 noninstrumental verbs. Half of the items were trained with orthographic information present. Verb learning was assessed using an animation-word matching and animation naming task. Linear mixed-effects models showed a main effect of group for all verb learning measures, demonstrating that children with LD learned fewer words and at a slower rate than the control group. No effect of verb instrumentality, presence of orthographic information, or the included mediators was found. Our results emphasize the importance of continued vocabulary instruction in elementary school to strengthen verb encoding. Given that our findings are inconsistent with the overall literature showing an orthographic facilitation effect, future studies should investigate whether participants pay attention to the written word form in learning contexts with moving stimuli.

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.

Semantic and Syntactic Properties of Words and the Receptive-Expressive Gap in Autistic and Non-Autistic Children.

PURPOSE: The goal of this work was to examine the semantic and syntactic properties of the vocabularies of autistic and non-autistic infants and toddlers to see if children in these two groups know different kinds of words. We focused on both receptive and expressive vocabularies. For expressive vocabulary, we looked only at the "active" lexicon: Of those words that are already in children's receptive vocabulary, we asked which ones they also produce. METHOD: We used an existing data set of 346 parent report vocabulary checklists (MacArthur-Bates Communicative Development Inventory: Words and Gestures) from 41 autistic and 27 non-autistic children at multiple timepoints between the ages of 6 and 43 months. We coded the words on the checklists for various semantic and syntactic properties and evaluated which properties predicted whether children understood and produced those words. RESULTS: Overall, we replicated a common finding that autistic children have smaller receptive vocabularies than non-autistic children, but we found that of the words they understand, autistic children produce a similar proportion of those words as non-autistic children. While we found that some syntactic properties are more or less likely to be represented in children's early vocabularies (e.g., nouns are more likely to be understood and produced than words that are not nouns), these patterns did not differ across autistic and non-autistic children. CONCLUSIONS: The semantic and syntactic compositions of autistic and non-autistic children's vocabularies are similar. Thus, while receptive vocabularies are relatively smaller for autistic children, they do not appear to have specific difficulty with words that have particular syntactic or semantic properties, or with adding words to the expressive vocabulary that they already understand.

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.

Frequency, Form and Function of Dyadic Questions in Children with Autism: A CHILDES corpus study.

Children's questions to their caregivers - and caregivers' questions to their children - play an important role in child development. For children on the autism spectrum, who often experience cognitive, linguistic and social difficulties, prior research on questions has resulted in inconsistent and incomplete findings. The present study characterized the frequency, form, and function of queries posed by children on the autism spectrum (n = 12), non-spectrum peers (n =20), and parents using the Nadig ASD English Corpus in the Child Language Data Exchange System (CHILDES). Results suggested that children on the autism spectrum and their caregivers produced fewer questions than non-spectrum dyads; however, whereas wh- questions were under-represented in the repertoire of children on the spectrum, they were over-represented in the repertoire of their parents. Finally, question function was similarly diverse for parents and children across groups. These findings offer important clinical implications for question-asking interventions targeting this population.

Parental tuning of language input to autistic and nonspectrum children.

Caregivers' language input supports children's language development, and it is often tuned to the child's current level of skill. Evidence suggests that parental input is tuned to accommodate children's expressive language levels, but accommodation to receptive language abilities is less understood. In particular, little is known about parental sensitivity to children's abilities to process language in real time. Compared to nonspectrum children, children on the spectrum are slower to process language. In this study, we ask: Do parents of autistic children and those of nonspectrum children tune their language input to accommodate children's different language processing abilities? Children with and without a diagnosis of autism (ages 2-6 years, N = 35) and their parents viewed a display of six images, one of which was the target. The parent labeled the target to direct the child's attention to it. We first examined children's language processing abilities by assessing their latencies to shift gaze to the labeled referent; from this, we found slower latencies in the autistic group than in the nonspectrum group, in line with previous findings. We then examined features of parents' language and found that parents in both groups produced similar language, suggesting that parents may not adjust their language input according to children's speed of language processing. This finding suggests that (1) capturing parental sensitivity to children's receptive language, and specifically language processing, may enrich our models of individual differences in language input, and (2) future work should investigate if supporting caregivers in tuning their language use according to children's language processing can improve children's language outcomes.

Consistency and inconsistency in caregiver reporting of vocabulary.

Vocabulary checklists completed by caregivers are a common way of measuring children's vocabulary knowledge. We provide evidence from checklist data from 31 children with and without autism spectrum disorder. When asked to report twice about whether or not their child produces a particular word, caregivers are largely consistent in their responses, but where they are inconsistent, these inconsistencies affect verbs more than nouns. This difference holds both for caregivers of children with autism spectrum disorder and caregivers of typically-developing children. We suggest that caregivers may be less sure of their child's knowledge about verbs than nouns. This data converges with prior evidence comparing language samples of words children produce in a recorded interaction with checklist data, and it has implications for how researchers use checklist data in cases where the reliability of estimates of verb knowledge is critical.

Mapping Word to World in ASL: Evidence from a Human Simulation Paradigm.

Across languages, children map words to meaning with great efficiency, despite a seemingly unconstrained space of potential mappings. The literature on how children do this is primarily limited to spoken language. This leaves a gap in our understanding of sign language acquisition, because several of the hypothesized mechanisms that children use are visual (e.g., visual attention to the referent), and sign languages are perceived in the visual modality. Here, we used the Human Simulation Paradigm in American Sign Language (ASL) to determine potential cues to word learning. Sign-naïve adult participants viewed video clips of parent-child interactions in ASL, and at a designated point, had to guess what ASL sign the parent produced. Across two studies, we demonstrate that referential clarity in ASL interactions is characterized by access to information about word class and referent presence (for verbs), similarly to spoken language. Unlike spoken language, iconicity is a cue to word meaning in ASL, although this is not always a fruitful cue. We also present evidence that verbs are highlighted well in the input, relative to spoken English. The results shed light on both similarities and differences in the information that learners may have access to in acquiring signed versus spoken languages.

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.

Three-year-olds' comprehension of contrastive and descriptive adjectives: Evidence for contrastive inference.

Combining information from adjectives with the nouns they modify is essential for comprehension. Previous research suggests that preschoolers do not always integrate adjectives and nouns, and may instead over-rely on noun information when processing referring expressions (Fernald, Thorpe, & Marchman, 2010; Thorpe, Baumgartner, & Fernald, 2006). This disjointed processing has implications for pragmatics, apparently preventing under-fives from making contrastive inferences (Huang & Snedeker, 2013). Using a novel experimental design that allows preschoolers time to demonstrate their abilities in adjective-noun integration and in contrastive inference, two visual world experiments investigate how English-speaking three-year-olds (N = 73, Mage = 44 months) process size adjectives across syntactic (prenominal; postnominal) and pragmatic (descriptive; contrastive) contexts. We show that preschoolers are able to integrate adjectives and nouns to resolve reference accurately by the end of the referring expression, in a variety of pragmatic and syntactic contexts and in the presence of multiple distractors. We reveal for the first time that they can contrastively infer, given a slowed speed of presentation and visually salient size contrasts. Our findings provide evidence for a continuity in the development of pragmatic skills, which do not appear to be linked to children's language proficiency or speed of processing.

Personal Pronoun Errors in Form versus Meaning Produced by Children with and without Autism Spectrum Disorder.

The current study investigates whether the types of pronominal errors children with autism spectrum disorder (ASD) make are different from those of their TD peers at similar stages of language development. A recent review about language acquisition in ASD argues that these children show relative deficits in assigning/extending lexical meaning alongside relative strengths in morpho-syntax (Naigles & Tek, 2017). Pronouns provide an ideal test case for this argument because they are marked both for grammatical features (case) and features that reflect qualities of the referent itself (gender and number) or the referent's role in conversation (person). The form-meaning hypothesis predicts that children with ASD should struggle more with these latter features. The current study tests this hypothesis with data from a caregiver report, completed by caregivers of 151 children with and without ASD. Reported pronominal errors were categorized as meaning or form and compared across groups. In accordance with the form-meaning hypothesis, a higher proportion of children with ASD make meaning errors than they do form errors, and significantly more of them make meaning errors than TD children do.

Linguistic context in verb learning: Less is sometimes more.

Linguistic contexts provide useful information about verb meanings by narrowing the space of candidate concepts. Intuitively, the more information, the better. For example, "the tall girl is fezzing," as compared to "the girl is fezzing," provides more information about which event, out of multiple candidate events, is being labeled; thus, we may expect it to better facilitate verb learning. However, we find evidence to the contrary: in a verb learning study, preschoolers (N = 60, mean age = 38 months) only performed above chance when the subject was an unmodified determiner phase, but not when it was modified (Experiment 1). Experiment 2 replicated this pattern with a different set of stimuli and a wider age range (N = 60, mean age = 45 months). Further, in Experiment 2, we looked at both learning outcomes--by evaluating pointing responses at Test, and also the learning process--by tracking eye gaze during Familiarization. The results suggest that children's limited processing abilities are to blame for poor learning outcomes, but that a nuanced understanding of how processing affects learning is required.

Two-year-olds consolidate verb meanings during a nap.

Successful word learning requires establishing an initial representation that is sufficiently robust to be retained in memory. Sleep has profound advantages for memory consolidation, but evidence concerning the effects of sleep in young children's word learning is slim and focuses almost exclusively on learning nouns. Verbs are representationally more complex and are often learned from non-concurrent linguistic and observational information (e.g., hearing "let's pour your milk" before the pouring event takes place). What remains unknown is whether initial representations built this way are robust enough to sustain a delay, and how these representations are affected by sleep. We presented two-year-olds with non-concurrent linguistic and observational information about novel verbs and immediately tested their knowledge of the verbs' meanings by evaluating their eye gaze as they looked at potential referents. Then, after a 4-hour delay during which half of the children napped and half remained awake, we retested them to see if they remembered the verbs' meanings. The results demonstrate differences in two-year-olds' representations of a novel verb before and after the delay; specifically, their verb representations withstood the 4-hour delay if they had napped, but decayed if they had remained awake.

Toddlers' word learning through overhearing: Others' attention matters.

In laboratory settings children are able to learn new words from overheard interactions, yet in naturalistic contexts this is often not the case. We investigated the degree to which joint attention within the overheard interaction facilitates overheard learning. In the study, 20 2-year-olds were tested on novel words they had been exposed to in two different overhearing contexts: one in which both interlocutors were attending to the interaction and one in which one interlocutor was not attending. Participants learned the new words only in the former condition, indicating that they did not learn when joint attention was absent. This finding demonstrates that not all overheard interactions are equally good for word learning; attentive interlocutors are crucial when learning words through overhearing.

Lexical processing of nouns and verbs at 36 months of age predicts concurrent and later vocabulary and school readiness.

Children's lexical processing speed at 18 to 25 months of age has been linked to concurrent and later language abilities. In the current study, we extend this finding to children aged 36 months. Children (N = 126) participated in a lexical processing task in which they viewed two static images on noun trials (e.g., an ear of corn and a hat), or two dynamic video clips on verb trials (e.g., a woman stretching and the same woman clapping), and heard an auditory prompt labeling one of them (e.g., "Where is she stretching?"). They also participated in standard assessments of language and school readiness. The results indicated that lexical processing speed (i.e., how long they required to look to the labeled image or scene) was associated with measures of concurrent receptive vocabulary, as well as receptive vocabulary and school readiness two years later, although the associations are weaker than for younger children.

The robustness of eye-mouth index as an eye-tracking metric of social attention in toddlers.

Eye-tracking research on social attention in infants and toddlers has included heterogeneous stimuli and analysis techniques. This allows measurement of looking to inner facial features under diverse conditions but restricts across-study comparisons. Eye-mouth index (EMI) is a measure of relative preference for looking to the eyes or mouth, independent of time spent attending to the face. The current study assessed whether EMI was more robust to differences in stimulus type than percent dwell time (PDT) toward the eyes, mouth, and face. Participants were typically developing toddlers aged 18 to 30 months (N = 58). Stimuli were dynamic videos with single and multiple actors. It was hypothesized that stimulus type would affect PDT to the face, eyes, and mouth, but not EMI. Generalized estimating equations demonstrated that all measures including EMI were influenced by stimulus type. Nevertheless, planned contrasts suggested that EMI was more robust than PDT when comparing heterogeneous stimuli. EMI may allow for a more robust comparison of social attention to inner facial features across eye-tracking studies.

Brief Report: Learning Language Through Overhearing in Children with ASD.

We explored whether children with autism spectrum disorder (ASD) learn new nouns from overheard speech. Thirteen children (4-5 years) with ASD participated in an Addressed condition, in which they were directly taught a novel label (e.g., toma) for one of three novel objects, and an Overheard condition, in which the objects and label were presented in a conversation between two adults. In both conditions, children were then asked to identify the labeled object (e.g., "find the toma"). Children selected the target novel object at rates above chance in the Addressed condition, and of critical importance, they also did so in the Overheard condition. This suggests that, like TD children, children with ASD may learn from language that is not directed to them.

Adjective forms and functions in British English child-directed speech.

Adjectives are essential for describing and differentiating concepts. However, they have a protracted development relative to other word classes. Here we measure three- and four-year-olds' exposure to adjectives across a range of interactive and socioeconomic contexts to: (i) measure the syntactic, semantic, and pragmatic variability of adjectives in child-directed speech (CDS); and (ii) investigate how features of the input might scaffold adjective acquisition. In our novel corpus of UK English, adjectives occurred more frequently in prenominal than in postnominal (predicative) syntactic frames, though postnominal frames were more frequent for less-familiar adjectives. They occurred much more frequently with a descriptive than a contrastive function, especially for less-familiar adjectives. Our findings present a partial mismatch between the forms of adjectives found in real-world CDS and those forms that have been shown to be more useful for learning. We discuss implications for models of adjective acquisition and for clinical practice.