Julia L. Evans

Can Infants Map Meaning to Newly Segmented Words? Statistical Segmentation and Word Learning

The present experiments investigated how the process of statistically segmenting words from fluent speech is linked to the process of mapping meanings to words. Seventeen-month-old infants first participated in a statistical word segmentation task, which was immediately followed by an object-label-learning task. Infants presented with labels that were words in the fluent speech used in the segmentation task were able to learn the object labels. However, infants presented with labels consisting of novel syllable sequences (nonwords; Experiment 1) or familiar sequences with low internal probabilities (part-words; Experiment 2) did not learn the labels. Thus, prior segmentation opportunities, but not mere frequency of exposure, facilitated infants∗ learning of object labels. This work provides the first demonstration that exposure to word forms in a statistical word segmentation task facilitates subsequent word learning.

Uses and interpretations of non‐word repetition tasks in children with and without specific language impairments (SLI)

BACKGROUND The non-word repetition task (NRT) has gained wide acceptance in describing language acquisition in both children with normal language development (NL) and children with specific language impairments (SLI). This task has gained wide acceptance because it so closely matches the phonological component of word learning, and correlates with measures of phonological working memory, a deficit in which is hypothesized to underlie SLI. AIMS/METHODS & PROCEDURES Recent uses of the NRT seem to accept it as a measure of phonological working memory capacity in spite of the fact that researchers have consistently acknowledged that the task taps many language processes, including speech perception, phonological encoding, phonological memory, phonological assembly and articulation. This paper reviews the literature on the use of the non-word repetition task (NRT) in children with NL and children with SLI, emphasizing the component skills necessary for successful repetition. MAIN CONTRIBUTION For children with NL, discussion has focused on (1) the relationship between non-word repetition ability and vocabulary, and (2) lexical and sublexical influences on repetition accuracy. For children with SLI, discussion has focused on these factors as well, but has also considered other component skills that support non-word repetition. Researchers have examined speech perception and discrimination, phonological encoding, phonological memory, phonological assembly, motor planning, and articulation, and have found evidence that children with SLI exhibit impairments in each of these supporting skills. CONCLUSIONS Because repetition accuracy depends on lexical and sublexical properties, the NRT can be used to examine the structural properties of the lexicon in both children with NL and with SLI. Further, because the task taps so many underlying skills, it is a powerful tool that can be used to identify children with language impairments.

The Role of Processing Limitations in Early Identification of Specific Language Impairment.

This article considers how information regarding processing limitations in children with specific language impairment (SLI) might be extended to assist in early identification of toddlers at risk for language disorder. A brief review of the evidence for processing capacity limitations in SLI is provided, along with results from longitudinal studies of toddlers with late onset of language development. Preliminary findings are presented from an ongoing investigation of early lexical processing for 15 late talking toddlers and 15 controls whose performance was assessed on a novel word learning task. Assessment implications of a processing based account of language impairment are discussed. Key words: assessment, cultural diversity, language disorder, language outcomes, late talkers, limited processing capacity, processing measures, specific language impairment

THE ROLE OF GESTURE IN CHILDREN'S COMPREHENSION OF SPOKEN LANGUAGE: NOW THEY NEED IT, NOW THEY DON'T

Two experiments investigated gesture as a form of external support for spoken language comprehension. In both experiments, children selected blocks according to a set of videotaped instructions. Across trials, the instructions were given using no gesture, gestures that reinforced speech, and gestures that conflicted with speech. Experiment 1 used spoken messages that were complex for preschool children but not for kindergarten children. Reinforcing gestures facilitated speech comprehension for preschool children but not for kindergarten children, and conflicting gestures hindered comprehension for kindergarten children but not for preschool children. Experiment 2 tested preschool children with simpler spoken messages. Unlike Experiment 1, preschool childrens comprehension was not facilitated by reinforcing gestures. However, childrens comprehension also was not hindered by conflicting gestures. Thus, the effects of gesture on speech comprehension depend both on the relation of gesture to speech, and on the complexity of the spoken message.

Divergence of verbal expression and embodied knowledge: Evidence from speech and gesture in children with specific language impairment

It has been suggested that phonological working memory serves to link speech comprehension to production. We suggest further that impairments in phonological working memory may influence the way in which children represent and express their knowledge about the world around them. In particular, children with severe phonological working memory deficits may have difficulty retaining stable representations of phonological forms, which results in weak links with meaning representations; however, nonverbal meaning representations might develop appropriately due to input from other modalities (e.g., vision, action). Typically developing children often express emerging knowledge in gesture before they are able to express this knowledge explicitly in their speech. In this study we explore the extent to which children with specific language impairment (SLI) with severe phonological working memory deficits express knowledge uniquely in gesture as compared to speech. Using a paradigm in which gesture-speech relationships have been studied extensively, children with SLI and conservation judgement-matched, typically developing controls were asked to solve and explain a set of Piagetian conservation tasks. When gestures accompanied their explanations, the children with SLI expressed information uniquely in gesture more often than did the typically developing children. Further, the children with SLI often expressed more sophisticated knowledge about conservation in gesture (and in some cases, distributed across speech and gesture) than in speech. The data suggest that for the children with SLI, their embodied, perceptually-based knowledge about conservation was rich, but they were not always able to express this knowledge verbally. We argue that this pattern of gesture-speech mismatch may be due to poor links between phonological representations and embodied meanings for children with phonological working memory deficits.

Continuity in lexical and morphological development in Icelandic and English-speaking 2-year-olds

Accounts of language development vary in whether they view lexical and grammatical development as being mediated by a single or by separate mechanisms. In a single mechanism account, only one system is required for learning words and extracting grammatical regularity based on similarities among stored items. A strong non-linear relationship between early lexical and grammatical development has been demonstrated in English and, more recently, in Italian supporting a single mechanism view (Caselli, Casadio & Bates 1999, Marchman & Bates 1994). The present study showed a comparable non-linear relationship between vocabulary size and the emergence of verb inflection and sentence complexity in two-year-old speakers of English and Icelandic, a highly inflected language. The study included 96 children within a narrow age range, but varying extensively in language proficiency, demonstrating continuity in lexical and grammatical development among children with typical language development as well as very precocious children and children with expressive language delay. Cross-linguistic differences were noted as well, suggesting that the Icelandic-speaking children required a larger critical mass of vocabulary items before grammatical regularity was detected. This is probably a result of the more complex inflectional system of the Icelandic language compared with English.

Relation of auditory attention and complex sentence comprehension in children with specific language impairment: A preliminary study

We investigated the relation of two dimensions of attentional functioning (sustained auditory attention and resource capacity/allocation) and complex sentence comprehension of children with specific language impairment (SLI) and a group of typically developing (TD) children matched for age. Twentysix school-age children with SLI and 26 TD peers completed an auditory continuous performance task (ACPT, measure of sustained attention), a concurrent verbal processing-storage task (measure of resource capacity/allocation), and a picture pointing comprehension task. Correlation analyses were run to determine the association between the measures of attention and sentence comprehension. The SLI group performed more poorly than the TD group across all tasks. For the SLI group, even after removing the effects of age, ACPT score and performance on the concurrent processing-storage task still significantly correlated with complex sentence comprehension. Sustained attention also correlated with simple sentence comprehension. Neither attention variable correlated with sentence comprehension in the TD children. For children with SLI, the comprehension of complex grammar appears to involve significant use of sustained attention and resource capacity/allocation. Even simple sentence comprehension requires significant auditory vigilance. In the case of TD children, neither complex nor simple sentence comprehension appears to invoke significant attentional involvement. Children with specific language impairment (SLI) have special difficulty comprehending complex grammar (Bishop, Bright, James, Bishop, & van der Lely, 2000; Montgomery & Evans, in press; Norbury, Bishop, & Briscoe, 2002; van der Lely, 1996, 1998; van der Lely & Stollwerck, 1997). Many of these same children

Theoretical perspectives on language and communication problems in mental retardation and developmental disabilities

We argue that researchers interested in language and communication problems in mental retardation or any other developmental disorder should view such problems as emerging within the broader context of the behavioral profile, or phenotype, associated with a particular genetic condition. This will require understanding the direct and indirect effects of genes on the development of language and communication and thereby an understanding of the complex relations that exist between language and other dimensions of psychological and behavioral functioning as well as an understanding of the environments in which the developing person acts and is acted upon. We believe that the dominant model for understanding language and communication problems--the nativist approach, which emphasizes the childs innate capacity for acquiring language and characterizes language as consisting of a set of context-free deterministic rules that operate on abstract representations--is inconsistent with an emphasis on indirect genetic effects. We review recent evidence that undermines the nativist approach--evidence concerning the initial state of the language-learning child, the role of environmental input, the competence-performance distinction, and modularity. In place of nativism, we argue for Emergentism, which is a model in which language is seen to emerge from the interaction between the childs biological abilities to map statistical properties of the language input into a distributed representation and the characteristics of the language learning environment and for the purpose of engaging in real-time, meaningful language use.

An emergent account of language impairments in children with SLI: Implications for assessment and intervention

While current theoretical accounts of language impairments in children with specific language impairment (SLI) provide clear direction with regard to intervention goal setting, these same accounts say little with regard to the intervention process. Current developments in connectionist modeling and the extension of principles of dynamical systems theory to cognitive and language development have resulted in a new theory of language development known as emergentism. In contrast to traditional formal linguistic accounts, the emergentist view holds that language is a dynamic evolving system that can be represented as a distribution of probabilistic information. Language acquisition, from this perspective, emerges from the childs simultaneous integration of multiple acoustic, linguistic, social and communicative cues within the context of the communicative interaction. An alternative account of SLI grounded within this emergentist view is presented, and preliminary implications are explored with respect to assessment and intervention.

Sentence processing strategies in children with expressive and expressive-receptive specific language impairments.

The purpose of this study was to investigate the sentence comprehension strategies used by children with expressive and expressive-receptive specific language impairments (SLI) within a language processing framework. Fourteen children with SLI (ages 6;10-7;11) meeting strict selection criteria were compared to seven age-matched and seven younger normal controls. Children were asked to determine the agent in sentences composed of two nouns and a verb (NVN, NNV, VNN) with animacy of the noun as a second factor. Results of group comparisons revealed that children with E-SLI and ER-SLI differed from each other in the comprehension strategies they employed as well as differing from both age-matched and younger normal language control groups. Children with E-SLI relied exclusively on a first noun as agent strategy across all conditions, whereas children with ER-SLI used animacy cues when available. Additionally, maximum likelihood estimates were calculated to investigate individual patterns of performance under different cue conditions. Results revealed a significant correlation between severity of receptive language abilities and the type of strategy used, with better receptive language skills being highly correlated with childrens use of word order cues.