Parent American Sign Language skills correlate with child-but not toddler-ASL vocabulary size.

Most deaf children have hearing parents who do not know a sign language at birth, and are at risk of limited language input during early childhood. Studying these children as they learn a sign language has revealed that timing of first-language exposure critically shapes language outcomes. But the input deaf children receive in their first language is not only delayed, it is much more variable than most first language learners, as many learn their first language from parents who are themselves new sign language learners. Much of the research on deaf children learning a sign language has considered the role of parent input using broad strokes, categorizing hearing parents as non-native, poor signers, and deaf parents as native, strong signers. In this study, we deconstruct these categories, and examine how variation in sign language skills among hearing parents might affect children's vocabulary acquisition. This study included 44 deaf children between 8- and 60-months-old who were learning ASL and had hearing parents who were also learning ASL. We observed an interactive effect of parent ASL proficiency and age, such that parent ASL proficiency was a significant predictor of child ASL vocabulary size, but not among the infants and toddlers. The proficiency of language models can affect acquisition above and beyond age of acquisition, particularly as children grow. At the same time, the most skilled parents in this sample were not as fluent as "native" deaf signers, and yet their children reliably had age-expected ASL vocabularies. Data and reproducible analyses are available at https://osf.io/9ya6h/.

Learning a Sign Language Does Not Hinder Acquisition of a Spoken Language.

PURPOSE: The purpose of this study is to determine whether and how learning American Sign Language (ASL) is associated with spoken English skills in a sample of ASL-English bilingual deaf and hard of hearing (DHH) children. METHOD: This cross-sectional study of vocabulary size included 56 DHH children between 8 and 60 months of age who were learning both ASL and spoken English and had hearing parents. English and ASL vocabulary were independently assessed via parent report checklists. RESULTS: ASL vocabulary size positively correlated with spoken English vocabulary size. Spoken English vocabulary sizes in the ASL-English bilingual DHH children in the present sample were comparable to those in previous reports of monolingual DHH children who were learning only English. ASL-English bilingual DHH children had total vocabularies (combining ASL and English) that were equivalent to same-age hearing monolingual children. Children with large ASL vocabularies were more likely to have spoken English vocabularies in the average range based on norms for hearing monolingual children. CONCLUSIONS: Contrary to predictions often cited in the literature, acquisition of sign language does not harm spoken vocabulary acquisition. This retrospective, correlational study cannot determine whether there is a causal relationship between sign language and spoken language vocabulary acquisition, but if a causal relationship exists, the evidence here suggests that the effect would be positive. Bilingual DHH children have age-expected vocabularies when considering the entirety of their language skills. We found no evidence to support recommendations that families with DHH children avoid learning sign language. Rather, our findings show that children with early ASL exposure can develop age-appropriate vocabulary skills in both ASL and spoken English.

Do parents modify child-directed signing to emphasize iconicity?

Iconic signs are overrepresented in the vocabularies of young deaf children, but it is unclear why. It is possible that iconic signs are easier for children to learn, but it is also possible that adults use iconic signs in child-directed signing in ways that make them more learnable, either by using them more often than less iconic signs or by lengthening them. We analyzed videos of naturalistic play sessions between parents and deaf children (n = 24 dyads) aged 9-60 months. To determine whether iconic signs are overrepresented during child-directed signing, we compared the iconicity of actual parent productions to the iconicity of simulated vocabularies designed to estimate chance levels of iconicity. For almost all dyads, parent sign types and tokens were not more iconic than the simulated vocabularies, suggesting that parents do not select more iconic signs during child-directed signing. To determine whether iconic signs are more likely to be lengthened, we ran a linear regression predicting sign duration, and found an interaction between age and iconicity: while parents of younger children produced non-iconic and iconic signs with similar durations, parents of older children produced non-iconic signs with shorter durations than iconic signs. Thus, parents sign more quickly with older children than younger children, and iconic signs appear to resist that reduction in sign length. It is possible that iconic signs are perceptually available longer, and their availability is a candidate hypothesis as to why iconic signs are overrepresented in children's vocabularies.

Perceptual optimization of language: Evidence from American Sign Language.

If language has evolved for communication, languages should be structured such that they maximize the efficiency of processing. What is efficient for communication in the visual-gestural modality is different from the auditory-oral modality, and we ask here whether sign languages have adapted to the affordances and constraints of the signed modality. During sign perception, perceivers look almost exclusively at the lower face, rarely looking down at the hands. This means that signs articulated far from the lower face must be perceived through peripheral vision, which has less acuity than central vision. We tested the hypothesis that signs that are more predictable (high frequency signs, signs with common handshapes) can be produced further from the face because precise visual resolution is not necessary for recognition. Using pose estimation algorithms, we examined the structure of over 2000 American Sign Language lexical signs to identify whether lexical frequency and handshape probability affect the position of the wrist in 2D space. We found that frequent signs with rare handshapes tended to occur closer to the signer's face than frequent signs with common handshapes, and that frequent signs are generally more likely to be articulated further from the face than infrequent signs. Together these results provide empirical support for anecdotal assertions that the phonological structure of sign language is shaped by the properties of the human visual and motor systems.

The ASL-LEX 2.0 Project: A Database of Lexical and Phonological Properties for 2,723 Signs in American Sign Language.

ASL-LEX is a publicly available, large-scale lexical database for American Sign Language (ASL). We report on the expanded database (ASL-LEX 2.0) that contains 2,723 ASL signs. For each sign, ASL-LEX now includes a more detailed phonological description, phonological density and complexity measures, frequency ratings (from deaf signers), iconicity ratings (from hearing non-signers and deaf signers), transparency ("guessability") ratings (from non-signers), sign and videoclip durations, lexical class, and more. We document the steps used to create ASL-LEX 2.0 and describe the distributional characteristics for sign properties across the lexicon and examine the relationships among lexical and phonological properties of signs. Correlation analyses revealed that frequent signs were less iconic and phonologically simpler than infrequent signs and iconic signs tended to be phonologically simpler than less iconic signs. The complete ASL-LEX dataset and supplementary materials are available at https://osf.io/zpha4/ and an interactive visualization of the entire lexicon can be accessed on the ASL-LEX page: http://asl-lex.org/.

Deaf Children of Hearing Parents Have Age-Level Vocabulary Growth When Exposed to American Sign Language by 6 Months of Age.

OBJECTIVE: To examine whether children who are deaf or hard of hearing who have hearing parents can develop age-level vocabulary skills when they have early exposure to a sign language. STUDY DESIGN: This cross-sectional study of vocabulary size included 78 children who are deaf or hard of hearing between 8 and 68 months of age who were learning American Sign Language (ASL) and had hearing parents. Children who were exposed to ASL before 6 months of age or between 6 and 36 months of age were compared with a reference sample of 104 deaf and hard of hearing children who have parents who are deaf and sign. RESULTS: Deaf and hard of hearing children with hearing parents who were exposed to ASL in the first 6 months of life had age-expected receptive and expressive vocabulary growth. Children who had a short delay in ASL exposure had relatively smaller expressive but not receptive vocabulary sizes, and made rapid gains. CONCLUSIONS: Although hearing parents generally learn ASL alongside their children who are deaf, their children can develop age-expected vocabulary skills when exposed to ASL during infancy. Children who are deaf with hearing parents can predictably and consistently develop age-level vocabularies at rates similar to native signers; early vocabulary skills are robust predictors of development across domains.

Current Research in Pragmatic Language Use Among Deaf and Hard of Hearing Children.

In this article, we provide a narrative review of research literature on the development of pragmatic skills and the social uses of language in children and adolescents, with a focus on those who are deaf and hard of hearing (DHH). In the review, we consider how pragmatic skills may develop over time for DHH children and adolescents depending on age, language context, amplification devices, and languages and communication modalities. The implications of these findings for enhancing intervention programs for DHH children and adolescents and for considering ideal contexts for optimizing the pragmatic development of DHH children are considered.

American Sign Language Interpreters in Public Schools: An Illusion of Inclusion that Perpetuates Language Deprivation.

PURPOSE: Many deaf children have limited access to language, spoken or signed, during early childhood - which has damaging effects on many aspects of development. There has been a recent shift to consider deafness and language deprivation as separate but related conditions. As such, educational plans should differentiate between services related to deafness and services related to language deprivation. DESCRIPTION: Many deaf children attend mainstream public schools, and the primary service offered to students who use American Sign Language (ASL) is generally a sign language interpreter. ASSESSMENT: We argue that while sign language interpreters can be an effective accommodation for deafness (i.e., students who are deaf and not language-deprived), there is no reason to believe they are an effective accommodation for language deprivation (i.e., students who are deaf and language-deprived). CONCLUSION: Using interpreters instead of appropriate educational supports may exacerbate symptoms of language deprivation by prolonging the period of time a child goes with limited access to language.

Reduced neural selectivity for mental states in deaf children with delayed exposure to sign language.

Language provides a rich source of information about other people's thoughts and feelings. Consequently, delayed access to language may influence conceptual development in Theory of Mind (ToM). We use functional magnetic resonance imaging and behavioral tasks to study ToM development in child (n = 33, 4-12 years old) and adult (n = 36) fluent signers of American Sign Language (ASL), and characterize neural ToM responses during ASL and movie-viewing tasks. Participants include deaf children whose first exposure to ASL was delayed up to 7 years (n = 12). Neural responses to ToM stories (specifically, selectivity of the right temporo-parietal junction) in these children resembles responses previously observed in young children, who have similar linguistic experience, rather than those in age-matched native-signing children, who have similar biological maturation. Early linguistic experience may facilitate ToM development, via the development of a selective brain region for ToM.

The ASL-CDI 2.0: An updated, normed adaptation of the MacArthur Bates Communicative Development Inventory for American Sign Language.

Vocabulary is a critical early marker of language development. The MacArthur Bates Communicative Development Inventory has been adapted to dozens of languages, and provides a bird's-eye view of children's early vocabularies which can be informative for both research and clinical purposes. We present an update to the American Sign Language Communicative Development Inventory (the ASL-CDI 2.0,  https://www.aslcdi.org ), a normed assessment of early ASL vocabulary that can be widely administered online by individuals with no formal training in sign language linguistics. The ASL-CDI 2.0 includes receptive and expressive vocabulary, and a Gestures and Phrases section; it also introduces an online interface that presents ASL signs as videos. We validated the ASL-CDI 2.0 with expressive and receptive in-person tasks administered to a subset of participants. The norming sample presented here consists of 120 deaf children (ages 9 to 73 months) with deaf parents. We present an analysis of the measurement properties of the ASL-CDI 2.0. Vocabulary increases with age, as expected. We see an early noun bias that shifts with age, and a lag between receptive and expressive vocabulary. We present these findings with indications for how the ASL-CDI 2.0 may be used in a range of clinical and research settings.

Degree and not type of iconicity affects sign language vocabulary acquisition.

Lexical iconicity-signs or words that resemble their meaning-is overrepresented in children's early vocabularies. Embodied theories of language acquisition predict that symbols are more learnable when they are grounded in a child's firsthand experiences. As such, pantomimic iconic signs, which use the signer's body to represent a body, might be more readily learned than other types of iconic signs. Alternatively, the structure mapping theory of iconicity predicts that learners are sensitive to the amount of overlap between form and meaning. In this exploratory study of early vocabulary development in American Sign Language (ASL), we asked whether type of iconicity predicts sign acquisition above and beyond degree of iconicity. We also controlled for concreteness and relevance to babies, two possible confounding factors. Highly concrete referents and concepts that are germane to babies may be amenable to iconic mappings. We reanalyzed a previously published set of ASL Communicative Development Inventory (CDI) reports from 58 deaf children learning ASL from their deaf parents (Anderson & Reilly, 2002). Pantomimic signs were more iconic than other types of iconic signs (perceptual, both pantomimic and perceptual, or arbitrary), but type of iconicity had no effect on acquisition. Children may not make use of the special status of pantomimic elements of signs. Their vocabularies are, however, shaped by degree of iconicity, which aligns with a structure mapping theory of iconicity, though other explanations are also compatible (e.g., iconicity in child-directed signing). Previously demonstrated effects of type of iconicity may be an artifact of the increased degree of iconicity among pantomimic signs. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The Road to Language Learning Is Not Entirely Iconic: Iconicity, Neighborhood Density, and Frequency Facilitate Acquisition of Sign Language.

Iconic mappings between words and their meanings are far more prevalent than once estimated and seem to support children's acquisition of new words, spoken or signed. We asked whether iconicity's prevalence in sign language overshadows two other factors known to support the acquisition of spoken vocabulary: neighborhood density (the number of lexical items phonologically similar to the target) and lexical frequency. Using mixed-effects logistic regressions, we reanalyzed 58 parental reports of native-signing deaf children's productive acquisition of 332 signs in American Sign Language (ASL; Anderson & Reilly, 2002) and found that iconicity, neighborhood density, and lexical frequency independently facilitated vocabulary acquisition. Despite differences in iconicity and phonological structure between signed and spoken language, signing children, like children learning a spoken language, track statistical information about lexical items and their phonological properties and leverage this information to expand their vocabulary.

ASL-LEX: A lexical database of American Sign Language.

ASL-LEX is a lexical database that catalogues information about nearly 1,000 signs in American Sign Language (ASL). It includes the following information: subjective frequency ratings from 25-31 deaf signers, iconicity ratings from 21-37 hearing non-signers, videoclip duration, sign length (onset and offset), grammatical class, and whether the sign is initialized, a fingerspelled loan sign, or a compound. Information about English translations is available for a subset of signs (e.g., alternate translations, translation consistency). In addition, phonological properties (sign type, selected fingers, flexion, major and minor location, and movement) were coded and used to generate sub-lexical frequency and neighborhood density estimates. ASL-LEX is intended for use by researchers, educators, and students who are interested in the properties of the ASL lexicon. An interactive website where the database can be browsed and downloaded is available at http://asl-lex.org .

Inflected words in production: Evidence for a morphologically rich lexicon.

Current evidence suggests that there is a difference between the representations of multimorphemic words in production and perception. In perception, it is widely believed that both whole-word and root representations exist, while in production there is little evidence for whole-word representations. The present investigation demonstrates that whole-word and root frequency independently predict the duration of words suffixed with -ing, -ed, and -s, which reveals that both root and word representations play a role in the production of inflected English words. In a second line of analysis, we find that the number of inflected phonological neighbours independently predicts the duration of monomorphemic words, which extends these results and suggests that whole-word representations exist at the lexical level. Together these results suggest that both root and word representations of inflected words are stored in the lexicon and are relevant for the production of both monomorphemic and multimorphemic words.

Lexical access in sign language: a computational model.

PSYCHOLINGUISTIC THEORIES HAVE PREDOMINANTLY BEEN BUILT UPON DATA FROM SPOKEN LANGUAGE, WHICH LEAVES OPEN THE QUESTION: How many of the conclusions truly reflect language-general principles as opposed to modality-specific ones? We take a step toward answering this question in the domain of lexical access in recognition by asking whether a single cognitive architecture might explain diverse behavioral patterns in signed and spoken language. Chen and Mirman (2012) presented a computational model of word processing that unified opposite effects of neighborhood density in speech production, perception, and written word recognition. Neighborhood density effects in sign language also vary depending on whether the neighbors share the same handshape or location. We present a spreading activation architecture that borrows the principles proposed by Chen and Mirman (2012), and show that if this architecture is elaborated to incorporate relatively minor facts about either (1) the time course of sign perception or (2) the frequency of sub-lexical units in sign languages, it produces data that match the experimental findings from sign languages. This work serves as a proof of concept that a single cognitive architecture could underlie both sign and word recognition.