Deaf children's non-verbal working memory is impacted by their language experience

Abstract

Several recent studies have suggested that deaf children perform more poorly on working memory tasks compared to hearing children, but these studies have not been able to determine whether this poorer performance arises directly from deafness itself or from deaf children's reduced language exposure. The issue remains unresolved because findings come mostly from (1) tasks that are verbal as opposed to non-verbal, and (2) involve deaf children who use spoken communication and therefore may have experienced impoverished input and delayed language acquisition. This is in contrast to deaf children who have been exposed to a sign language since birth from Deaf parents (and who therefore have native language-learning opportunities within a normal developmental timeframe for language acquisition). A more direct, and therefore stronger, test of the hypothesis that the type and quality of language exposure impact working memory is to use measures of non-verbal working memory (NVWM) and to compare hearing children with two groups of deaf signing children: those who have had native exposure to a sign language, and those who have experienced delayed acquisition and reduced quality of language input compared to their native-signing peers. In this study we investigated the relationship between NVWM and language in three groups aged 6–11 years: hearing children (n = 28), deaf children who were native users of British Sign Language (BSL; n = 8), and deaf children who used BSL but who were not native signers (n = 19). We administered a battery of non-verbal reasoning, NVWM, and language tasks. We examined whether the groups differed on NVWM scores, and whether scores on language tasks predicted scores on NVWM tasks. For the two executive-loaded NVWM tasks included in our battery, the non-native signers performed less accurately than the native signer and hearing groups (who did not differ from one another). Multiple regression analysis revealed that scores on the vocabulary measure predicted scores on those two executive-loaded NVWM tasks (with age and non-verbal reasoning partialled out). Our results suggest that whatever the language modality—spoken or signed—rich language experience from birth, and the good language skills that result from this early age of acquisition, play a critical role in the development of NVWM and in performance on NVWM tasks.

Expressive Vocabulary Predicts Nonverbal Executive Function: A 2‐year Longitudinal Study of Deaf and Hearing Children

“…A recent study with a group of native deaf signers (i.e., born to deaf parents and therefore benefitting from language exposure from birth) found no difference in parental ratings on a questionnaire measuring different domains of EF (Hall, Eigsti, Bortfeld, & Lillo‐Martin, ). A similar lack of group differences was found by comparing the native signers from our study sample to hearing children on nonverbal tasks of working memory (Marshall et al., ). Both these studies would support our conclusions that good early child–parent interaction and later use of optimal self‐talk via age appropriate vocabulary will protect DHH children from EF delays.…”

Nonverbal Executive Function is Mediated by Language: A Study of Deaf and Hearing Children

“…Furthermore, we have not included the specific language history of deaf children within these complex analyses because subsample sizes become too small. However, when native signers have been considered in other studies, the same conclusion regarding language and cognition emerges: Native signers do not show the same working memory deficits as matched non‐native signers when compared to hearing peers, suggesting that rich language environment matters for EF development (Marshall et al., ) rather than auditory input per se as suggested by some theorists (e.g., auditory scaffolding hypothesis; Conway, Pisoni & Kronenberger, ). Therefore, it is not the case that all deaf children have difficulties with language and EF.…”

“…As noted earlier, other studies have reported difficulties for deaf children on EF tasks, but these studies have important limitations. Previous results have been drawn from small groups of deaf children (Marshall et al., ), often only recruited from selected deaf groups such as those with cochlear implants (Kronenberger et al., ) or with hearing aids (Stiles et al., ), that cross a wider age range (Luckner & McNeill, ), and which have used only one or two experimental tasks or tasks that are not genuinely comparable across deaf and hearing groups (Oberg & Lukomski, ; Remine, Care, & Brown, ; Surowiecki et al., ). Other studies (Hauser, Lukomski, & Samar, ; Hintermair, ) have relied entirely on parent and teacher questionnaires such as the Behavior Rating Inventory of Executive Function (Gioia, Isquith, Guy, & Kenworthy, ), which may measure different behaviors compared to direct assessments (Jahromi, Bryce, & Swanson, ).…”

Attention to speech and spoken language development in deaf children with cochlear implants: a 10‐year longitudinal study

“…Some evidence suggests that the cognitive processes required for modality independent processing are not affected by hearing loss in these children, who achieve typical language and social milestones in infancy (Hall et al, 2017;Marshall et al, 2015;Peterson & Siegal, 2000;Petitto & Marentette, 1991). For example, Hall et al (2017) examined executive function in a group of Deaf children from Deaf families, who have a history of auditory but not language deprivation.…”