It is widely recognized that deaf children take longer to learn a language than hearing children. Nevertheless, there are conflicting accounts of the underlying cause. Some have argued that it is the consequences of sensory deprivation that result in slower development. In contrast, others have contended the problem derives from the difficulties inherent in early language learning for hearing impaired children. This article explores research suggesting that these views can be reconciled, pointing to an explanation involving perceptual and cognitive factors.
It is recommended that deaf infants are faced with difficulty hearing important linguistic cues before they even begin to speak or understand words. Consequently, during this early period, their perceptions may not be optimal for them to later achieve complete competence in English grammar (or any other spoken language). Since many aspects of cognition (including speech perception) may depend on specific experiences during the early years, it is argued that this reduced opportunity for language learning to occur can have far-reaching consequences later in life.
Different theories about why deaf children take longer than hearing children develop language skills have been proposed. Some linguists argue that deaf children take so long because they do not hear any words when they are young and therefore cannot learn them quickly. Others say nothing special about learning spoken languages; all normal infants acquire their native language with ease, though not necessarily perfectly. These supporters argue that delays in receiving linguistic knowledge are due to a general cognitive deficit rather than a lack of auditory experience. Similarly, some educationists believe that uncertainties in linguistic development are inherent because deaf children often do not learn sign language until they go to school.
Generally speaking, there is little dispute about these general theories about why deaf infants take longer to develop standard language skills. Unfortunately, it may be more challenging to ascertain precisely why this occurs. All three factors may be involved in at least some cases where a child fails to acquire normal linguistic abilities during infancy or early childhood. However, it seems implausible that all three factors are inevitably at work in every case of delayed language acquisition by prelingually deaf individuals. Perhaps all that is needed to understand the nature of linguistic development in deaf individuals’ is to focus on individual differences regarding when and how much auditory experience they have.
Presumably, the best way to test these hypotheses would be through longitudinal studies following many children from infancy until at least their teenage years. This type of research has been carried out with hearing children. However, there has not been such a detailed investigation into why some prelingually deaf children develop normal language abilities while others do not. Therefore we cannot say which factors are most important at different stages during childhood and adolescence. At present, we will consider whether it is possible to distinguish between general explanations and accounts which focus specifically on language acquisition.