Blog Archives

Fast Mapping and Word Learning by Preschoolers With Specific Language Impairment in a Supported Learning Context: Effect of Encoding Cues, Phonotactic Probability, and Object Familiarity

Conclusion: The results suggest that phonotactic probability and previous lexical knowledge affect word learning in similar ways for children with TD and SLI and that encoding cues were not beneficial for any group.

from the Journal of Speech, Language, and Hearing Research

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Phonological learning in semantic dementia

Patients with semantic dementia (SD) have anterior temporal lobe (ATL) atrophy that gives rise to a highly selective deterioration of semantic knowledge. Despite pronounced anomia and poor comprehension of words and pictures, SD patients have well-formed, fluent speech and normal digit span. Given the intimate connection between phonological STM and word learning revealed by both neuropsychological and developmental studies, SD patients might be expected to show good acquisition of new phonological forms, even though their ability to map these onto meanings is impaired. In contradiction of these predictions, a limited amount of previous research has found poor learning of new phonological forms in SD. In a series of experiments, we examined whether SD patient, GE, could learn novel phonological sequences and, if so, under which circumstances. GE showed normal benefits of phonological knowledge in STM (i.e., normal phonotactic frequency and phonological similarity effects) but reduced support from semantic memory (i.e., poor immediate serial recall for semantically degraded words, characterised by frequent item errors). Next, we demonstrated normal learning of serial order information for repeated lists of single-digit number words using the Hebb paradigm: these items were well-understood allowing them to be repeated without frequent item errors. In contrast, patient GE showed little learning of nonsense syllable sequences using the same Hebb paradigm. Detailed analysis revealed that both GE and the controls showed a tendency to learn their own errors as opposed to the target items. Finally, we showed normal learning of phonological sequences for GE when he was prevented from repeating his errors. These findings confirm that the ATL atrophy in SD disrupts phonological processing for semantically-degraded words but leaves the phonological architecture intact. Consequently, when item errors are minimised, phonological STM can support the acquisition of new phoneme sequences in patients with SD.

from Neuropsychologia

Mutual exclusivity in autism spectrum disorders: Testing the pragmatic hypothesis

While there is ample evidence that children treat words as mutually exclusive, the cognitive basis of this bias is widely debated. We focus on the distinction between pragmatic and lexical constraints accounts. High-functioning children with autism spectrum disorders (ASD) offer a unique perspective on this debate, as they acquire substantial vocabularies despite impoverished social-pragmatic skills. We tested children and adolescents with ASD in a paradigm examining mutual exclusivity for words and facts. Words were interpreted contrastively more often than facts. Word performance was associated with vocabulary size; fact performance was associated with social-communication skills. Thus mutual exclusivity does not appear to be driven by pragmatics, suggesting that it is either a lexical constraint or a reflection of domain-general learning processes.

from Cognition

Examining the role of social cues in early word learning

Infants watched a video of an adult pointing towards two different objects while hearing novel labels. Analyses indicated that 14- and 18-month-olds looked longer at the target object, but only 18-month-olds showed word learning. The results suggest that different types of social cues are available at different ages.

from Infant Behavior and Development

Accessing the unsaid: The role of scalar alternatives in children’s pragmatic inference

When faced with a sentence like, “Some of the toys are on the table”, adults, but not preschoolers, compute a scalar implicature, taking the sentence to imply that not all the toys are on the table. This paper explores the hypothesis that children fail to compute scalar implicatures because they lack knowledge of relevant scalar alternatives to words like “some”. Four-year-olds were shown pictures in which three out of three objects fit a description (e.g., three animals reading), and were asked to evaluate statements that relied on context-independent alternatives (e.g., knowing that all is an alternative to some for the utterance “Some of the animals are reading”) or contextual alternatives (e.g., knowing that the set of all three visible animals is an alternative to a set of two for the utterance “Only the cat and the dog are reading”). Children failed to reject the false statements containing context-independent scales even when the word only was used (e.g., only some), but correctly rejected equivalent statements containing contextual alternatives (e.g., only the cat and dog). These results support the hypothesis that children’s difficulties with scalar implicature are due to a failure to generate relevant alternatives for specific scales. Consequences for number word learning are also discussed.

from Cognition

Sound before Meaning: Word Learning in Autistic Disorders

Successful word learning depends on the integration of phonological and semantic information with social cues provided by interlocutors. How then, do children with autism spectrum disorders (ASD) learn new words when social impairments pervade? We recorded the eye-movements of verbally-able children with ASD and their typical peers while completing a word learning task in a social context. We assessed learning of semantic and phonological features immediately after learning and again four weeks later. Eye-movement data revealed that both groups could follow social cues, but that typically developing children were more sensitive to the social informativeness of gaze cues. In contrast, children with ASD were more successful than peers at mapping phonological forms to novel referents; however, this advantage was not maintained over time. Typical children showed clear consolidation of learning both semantic and phonological information, children with ASD did not. These results provide unique evidence of qualitative differences in word learning and consolidation and elucidate the different mechanisms underlying the unusual nature of autistic language.

from Neuropsychologia

Phonological working memory impairments in children with specific language impairment: where does the problem lie?

Conclusions
We were able to ascertain which aspects of lexical learning are most problematic for children with SLI in terms of fast-mapping. These findings may allow clinicians to focus intervention on known areas of weakness. Future directions include extending these findings to slow mapping scenarios.

from the Journal of Communication Disorders

Differentiating the Effects of Phonotactic Probability and Neighborhood Density on Vocabulary Comprehension and Production: A Comparison of Preschool Children With Versus Without Phonological Delays

Conclusions: Rare sound sequences and sparse neighborhoods may facilitate triggering of word learning for typically developing children and children with phonological delays. In contrast, common sound sequences and dense neighborhoods may facilitate configuration and engagement for typically developing children but not for children with phonological delays because of their weaker phonological and/or lexical representations.

from the Journal of Speech, Language, and Hearing Research

The associative structure of language: Contextual diversity in early word learning

Previous studies demonstrated that statistical properties of adult generated free associates predict the order of early noun learning. We investigate an explanation for this phenomenon that we call the associative structure of language: early word learning may be driven in part by contextual diversity in the learning environment, with contextual diversity in caregiver speech correlating with the cue–target structure in adult free association norms. To test this, we examined the co-occurrence of words in caregiver speech from the CHILDES database and found that a word’s contextual diversity—the number of unique word types a word co-occurs with in caregiver speech—predicted the order of early word learning and was highly correlated with the number of unique associative cues for a given target word in adult free association norms. The associative structure of language was further supported by an analysis of the longitudinal development of early semantic networks (from 16 to 30 months) using contextual co-occurrence. This analysis supported two growth processes: The lure of the associates, in which the earliest learned words have more connections with known words, and preferential acquisition, in which the earliest learned words are the most contextually diverse in the learning environment. We further discuss the impact of word class (nouns, verbs, etc.) on these results.

from the Journal of Memory and Language

The associative structure of language: Contextual diversity in early word learning

Previous studies demonstrated that statistical properties of adult generated free associates predict the order of early noun learning. We investigate an explanation for this phenomenon that we call the associative structure of language: early word learning may be driven in part by contextual diversity in the learning environment, with contextual diversity in caregiver speech correlating with the cue–target structure in adult free association norms. To test this, we examined the co-occurrence of words in caregiver speech from the CHILDES database and found that a word’s contextual diversity—the number of unique word types a word co-occurs with in caregiver speech—predicted the order of early word learning and was highly correlated with the number of unique associative cues for a given target word in adult free association norms. The associative structure of language was further supported by an analysis of the longitudinal development of early semantic networks (from 16 to 30 months) using contextual co-occurrence. This analysis supported two growth processes: The lure of the associates, in which the earliest learned words have more connections with known words, and preferential acquisition, in which the earliest learned words are the most contextually diverse in the learning environment. We further discuss the impact of word class (nouns, verbs, etc.) on these results.

from the Journal of Memory and Language

Word Learning in Children With Primary Language Impairment: A Meta-Analysis

Conclusion: The difference in novel word learning performance between children with LI and age-matched children is strongly affected by task and participant characteristics in the primary studies.

from the Journal of Speech, Language, and Hearing Research

Learning to use words: Event-related potentials index single-shot contextual word learning

Humans have the remarkable capacity to learn words from a single instance. The goal of this study was to examine the impact of initial learning context on the understanding of novel word usage using event-related brain potentials. Participants saw known and unknown words in strongly or weakly constraining sentence contexts. After each sentence context, word usage knowledge was assessed via plausibility ratings of these words as the objects of transitive verbs. Plausibility effects were observed in the N400 component to the verb only when the upcoming novel word object had initially appeared in a strongly constraining context. These results demonstrate that rapid word learning is modulated by contextual constraint and reveal a rapid mental process that is sensitive to novel word usage.

from Cognition

A cross-sectional comparison of the effects of phonotactic probability and neighborhood density on word learning by preschool children

Two experiments examined the effects of phonotactic probability and neighborhood density on word learning by 3-, 4-, and 5-year-old children. Nonwords orthogonally varying in probability and density were taught with learning and retention measured via picture naming. Experiment 1 used a within story probability/across story density exposure context. Experiment 2 used an across story probability/within story density exposure context. Results showed that probability and density interacted to create optimal learning conditions. Specifically, rare/sparse sound sequences appeared to facilitate triggering of word learning. In contrast, the optimal convergence for lexical configuration and engagement was dependent on exposure context. In particular, common sound sequences and dense neighborhoods were optimal when density was manipulated across stories, whereas rare sound sequences and sparse neighborhoods were optimal when density was manipulated within a story. Taken together, children’s phonological and lexical representations were hypothesized to be interdependent on one another resulting in a convergence of form characteristics for optimal word learning.

from the Journal of Memory and Language

Word frequency as a cue for identifying function words in infancy

While content words (e.g., ‘dog’) tend to carry meaning, function words (e.g., ‘the’) mainly serve syntactic purposes. Here, we ask whether 17-month old infants can use one language–universal cue to identify function word candidates: their high frequency of occurrence. In Experiment 1, infants listened to a series of short, naturally recorded sentences in a foreign language (i.e., in French). In these sentences, two determiners appeared much more frequently than any content word. Following this, infants were presented with a visual object, and simultaneously with a word pair composed of a determiner and a noun. Results showed that infants associated the object more strongly with the infrequent noun than with the frequent determiner. That is, when presented with both the old object and a novel object, infants were more likely to orient towards the old object when hearing a label with a new determiner and the old noun compared to a label with a new noun and the old determiner. In Experiment 2, infants were tested using the same procedure as in Experiment 1, but without the initial exposure to French sentences. Under these conditions, infants did not preferentially associate the object with nouns, suggesting that the preferential association between nouns and objects does not result from specific acoustic or phonological properties. In line with various biases and heuristics involved in acquiring content words, we provide the first direct evidence that infants can use distributional cues, especially the high frequency of occurrence, to identify potential function words.

from Cognition

Initial Acquisition of Mental Graphemic Representations in Children with Language Impairment

Conclusions: The authors propose that children with LI are less robust at developing initial MGRs than are children with TL and that this poor ability to acquire initial MGRs likely places them at risk for later literacy deficits.

from the Journal of Speech, Language, and Hearing Research