Delayed auditory experience results in past tense production difficulties and working memory deficits in children with cochlear implants: A comparison with children with developmental language disorder.

Extent evidence has shown that morphosyntax is one of the most challenging linguistic areas for children with atypical early language experiences. Over the last couple of years, comparisons between deaf children with CIs and children with DLD have gained interest - as cases of atypical early language experiences, including, but not restricted to, delayed onset of exposure to language input and language-processing difficulties. Evidence suggests that the morphosyntactic difficulties experienced by deaf children with CIs and children with DLD are very similar in nature. However, the few studies that have directly compared both groups are inconclusive, with deaf children with CIs either performing significantly better or on par with children with DLD. These differences in findings can be attributed, in part at least, to a failure to implement essential methodological controls - even more so given that deaf children with CIs comprise a very diverse population. The goal of the present study was to directly compare the performance of deaf children with CIs to that of children with DLD on a morphosyntactic ability known to be particularly difficult for both groups. Specifically, the present study conducted a detailed examination of the past tense marking abilities of deaf children with CIs and children with DLD while controlling for factors specific to deaf children with CIs, for children's basic cognitive abilities as well as for children's age, sex assigned at birth, and SES. Past tense verbs are particularly relevant as they are used as a marker of developmental language disorder (DLD) in children learning French. Moreover, extent evidence shows that deaf children with CIs and children with DLD have important WM difficulties, but also that there is an association between auditory perception, processing abilities, and working memory (WM) abilities as well as with the acquisition of morphological features, including tense marking. Unfortunately, no study has examined the relation between the accurate production of past tense verbs and WM abilities in children with CIs and children with DLD learning French. Fifteen deaf children with CIs between 5 and 7 years of age were compared to 15 children with DLD and to 15 typically-developing monolingual controls (MON), matched on important variables, using a past tense elicitation task as well as measures of phonological and nonverbal WM abilities. The results confirm that the deaf children with CIs and the children with DLD both performed significantly lower than the MON controls on the past tense elicitation task - suggesting that difficulties with past tense verbs in French might not only be a marker of DLD but, instead, a correlate of atypical language acquisition. Of importance, the present study is the first to show that deaf children with CIs perform significantly lower than children with DLD on a past tense elicitation task - highlighting the importance of using methodological controls. As well, significant correlations were found between the performance of the deaf children with CIs and of the children with DLD on the past tense elicitation task and their phonological and nonverbal WM abilities. Taken together with previous studies conducted in the same populations, this represents another evidence suggesting that early atypical language experiences result in language and WM deficits, including morphosyntactic difficulties.

Exposure to sign language prior and after cochlear implantation increases language and cognitive skills in deaf children.

Recent evidence suggests that deaf children with CIs exposed to nonnative sign language from hearing parents can attain age-appropriate vocabularies in both sign and spoken language. It remains to be explored whether deaf children with CIs who are exposed to early nonnative sign language, but only up to implantation, also benefit from this input and whether these benefits also extend to memory abilities, which are strongly linked to language development. The present study examined the impact of deaf children's early short-term exposure to nonnative sign input on their spoken language and their phonological memory abilities. Deaf children who had been exposed to nonnative sign input before and after cochlear implantation were compared to deaf children who never had any exposure to sign input as well as to children with typical hearing. The children were between 5;1 and 7;1 years of age at the time of testing and were matched on age, sex, and socioeconomic status. The results suggest that even short-term exposure to nonnative sign input has positive effects on general language and phonological memory abilities as well as on nonverbal working memory-with total length of exposure to sign input being the best predictor of deaf children's performance on these measures. The present data suggest that even access to early short-term nonnative visual language input is beneficial for the language and phonological memory abilities of deaf children with cochlear implants, suggesting also that parents should not be discouraged from learning and exposing their child to sign language. RESEARCH HIGHLIGHTS: This is the first study to examine the effects of early short-term exposure to nonnative sign input on French-speaking children with cochlear implants' spoken language and memory abilities. Early short-term nonnative exposure to sign input can have positive consequences for the language and phonological memory abilities of deaf children with CIs. Extended exposure to sign input has some additional and important benefits, allowing children to perform on par with children with typical hearing.

A multi-group approach to examining language development in at-risk learners.

A battery of standardized language tests and control measures was administered to three groups of at-risk language learners - internationally adopted children, deaf children with cochlear implants, and children with specific language impairment - and to groups of second-language learners and typically developing monolingual children. All children were acquiring French, were matched on age, gender, and socioeconomic status, and were between age 5;0 and 7;3 at the time of testing. Differences between the at-risk and not-at-risk groups were evident in all domains of language testing. The children with SLI or CIs scored significantly lower than the IA children and all three at-risk groups scored lower than the monolingual group; the L2 and IA groups scored similarly. The results suggest that children with limited access to, or ability to process, early language input are at greater risk than children with delayed input to an additional language but otherwise typical or relatively typical early input.

Gesture and early bilingual development.

The relationship between speech and gestural proficiency was investigated longitudinally (from 2 years to 3 years 6 months, at 6-month intervals) in 5 French-English bilingual boys with varying proficiency in their 2 languages. Because of their different levels of proficiency in the 2 languages at the same age, these children's data were used to examine the relative contribution of language and cognitive development to gestural development. In terms of rate of gesture production, rate of gesture production with speech, and meaning of gesture and speech, the children used gestures much like adults from 2 years on. In contrast, the use of iconic and beat gestures showed differential development in the children's 2 languages as a function of mean length of utterance. These data suggest that the development of these kinds of gestures may be more closely linked to language development than other kinds (such as points). Reasons why this might be so are discussed.

Language differentiation in early bilingual development.

It has been claimed that children simultaneously acquiring two languages go through an initial stage when they are unable to differentiate between their two languages. Such claims have been based on the observation that at times virtually all bilingual children mix elements (e.g. lexical, morphological) from their two languages in the same utterance. That most, if not all, children acquiring two languages simultaneously mix linguistic elements in this way is widely documented. Although such code-mixing is not well understood or explained, there are a number of explanations unrelated to lack of language differentiation that may explain it. Moreover, while language differentiation is widely attested among bilingual children once functional categories emerge, usually during the third year, there is still some question as to how early in development differentiation is present. In this study, we examined language differentiation in five bilingual children prior to the emergence of functional categories (they ranged in age from 1;10 to 2;2 and in MLU from 1.23 to 2.08). They were observed with each parent separately and both together, on separate occasions. Our results indicate that while these children did code mix, they were clearly able to differentiate between their two languages. We also examine the possibility that the children's mixing is due to (a) their language dominance, and (b) their parents' rate of mixing. We could find no evidence that their mixing was due to parental input, but there was some evidence that language dominance played a role.

Phonological awareness in young second language learners.

English-speaking children (N = 91) who were attending French schools (bilingual group) were given a battery of phonological awareness tests in kindergarten and in grade I. At the time of kindergarten testing the mean age of the children was 5:9. Their performance was compared to age-matched English-speaking children (N = 72) attending English schools (monolingual group). The bilingual children showed heightened levels of phonological awareness skills in kindergarten in the area of onset-rime awareness. By grade I, the pattern of group differences was more complex. The monolingual and bilingual children performed similarly on onset-rime segmentation tasks. The monolingual children had higher phoneme awareness scores than their French-schooled peers; this result is interpreted to reflect the role of literacy instruction on phoneme awareness development. In comparison, the bilingual children had higher syllable segmentation scores than their monolingual peers. This result is interperted to reflect the role of second language input on phonological awareness.

Early bilingual development: one language or two?

It is commonly thought that children learning two languages simultaneously during infancy go through a stage when they cannot differentiate their two languages. Virtually all studies of infant bilingual development have found that bilingual children mix elements from their two languages. These results have been interpreted as evidence for a unitary, undifferentiated language system (the unitary language system hypothesis). The empirical basis for these claims is re-examined and it is argued that, contrary to most extant interpretations, bilingual children develop differentiated language systems from the beginning and are able to use their developing languages in contextually sensitive ways. A call for more serious attention to the possible role of parental input in the form of mixed utterances is made.

Lateral eye movements during verbal and nonverbal dichotic listening.

A dichotic listening paradigm was used to study the relation of eye movement to cerebral lateralization. The eye movements of right-handed subjects were recorded during verbal and nonverbal dichotic-listening tasks. Subjects given a verbal dichotic-listening task made significantly more rightward than leftward eye movements and showed more accuracy and speed in processing information presented to the right than to the left ear. Subjects given a nonverbal dichotic-listening task made significantly more leftward eye movements and processed better information presented to the left ear. These findings suggest a potentially strong link between the direction of lateral eye movement during dichotic listening tasks and left- and right-ear advantages in performance on such tasks. They also suggest that both eye movement and ear performance may be related to cerebral laterality and when examined in combination both could provide valuable information for the further study of hemispheric specialization.