Working Memory in Deaf Children Is Explained by the Developmental Ease of Language Understanding (D-ELU) Model

A commentary on Deaf children's non-verbal working memory is impacted by their language experience. The ability to keep information in mind for processing is known as working memory and is vital for learning. Children who have difficulty keeping up in school may have working memory limitations rather than limitations in the specific tasks they are assigned. In particular, children with functional impairments at the sensory or cognitive level may have difficulty performing tasks, either because the impairment hinders the development of the working memory system as such or because it hinders the development of linguistic and cognitive skills underpinning working memory development. Marshall et al. (2015) studied this issue by investigating working memory and its relation to language processing in two different groups of deaf children: native users of British Sign Language (BSL) and non-native BSL users, as well as in a control group of typically developing children with no hearing difficulties and no knowledge of sign language. The native signers had at least one deaf parent who had communicated in sign language with their child since birth. The non-native signers had acquired sign language later. All three groups performed two executively demanding non-verbal working memory tasks as well as an expressive vocabulary test and a narration task based on a filmed scenario enacted in BSL. Results showed that the non-native signers performed more poorly than the hearing participants on both working memory tasks while there was no difference in performance between the native signers and the hearing participants. The non-native signers had poorer vocabulary scores than the native signers who in turn had poorer vocabulary scores than the hearing children. However, there were no group differences on the narration task. Regression analysis showed that vocabulary was a significant unique predictor of performance on both of the working memory tasks. This association was all the more striking considering that there were no explicit demands on verbal skills in the working memory tasks. Marshall et al. (2015) argue that this pattern of results allows them to tease apart effects of auditory and language experience: while both of the deaf groups have experienced auditory deprivation, only one of them (non-native signers) has reduced language experience. In particular, the authors' interpretation is that while both auditory deprivation and reduced language experience have an impact on vocabulary development, reduced