Cochlear implants and hearing loss: A new look at the "Forbidden Experiment" in language development and the evolution of spoken language

David Pisoni, Indiana University

Cochlear implants work and they work well in restoring hearing to a large number of profoundly deaf children and adults. For prelingually deaf infants and very young children, cochlear implantation is now the standard of care in the medical field for the treatment of profound deafness. Despite the efficacy of cochlear implantation, there still remain a number of significant unresolved issues related to the effectiveness of cochlear implants in infants, children and adults. In addition to the clinical issues related to the medical treatment of deafness, there are also a number of broader theoretical issues related to language acquisition, neural plasticity and brain development in prelingually deaf children. The enormous individual differences routinely observed in speech and language outcomes following implantation is an important unresolved problem that has not been satisfactorily resolved. In this presentation, I discuss several broad issues related to the effects of early auditory deprivation on speech and language development within the context of recent work on cochlear implants. In many respects, current research on cochlear implants can be thought of as the modern equivalent of the "forbidden experiment" in the field of language development (where some children are deprived of access to language) but with an intervention that partially restores hearing to a damaged sensory system supporting the development of language and cognitive skills.