Cognition, Education, and Deafness: Directions for Research and Instruction

Cognition, Education, and Deafness: The Challenge

Cognition, Education, and Deafness: The Challenge Edward E. Corbett, Jr. We, in the field of deafness, have a great need to start a process by which new knowledge can be created. This process must begin by providing educators and researchers in deafness with the opportunity to probe at increasingly deeper levels into the areas of cognition, education, and deafness. We must go beyond our present efforts and extend research opportunities to more people, thus ensuring contributions from a much broader base. One way in which we can broaden our knowledge is by studying the cerebral cortex. Over the years we have studied the brain's control over the hearing and speech processes. This study has provided us with information about disturbances in hearing and speech caused by the pathology of the ear; the disruption of the eighth cranial nerve; and the pathology of the brain itself, which makes it difficult to analyze or produce sound. In the last few years, researchers have described the mechanism whereby nerve impulses in individual auditory nerve fibers are initiated by receptor organs. Researchers also have been working on hearing aids to regulate the intensity of sound. Recent experiments with cochlear implants that evoke the electrical potential within the cochlea to stimulate hearing are making important progress. In August 1983, Time magazine carried a cover story entitled, "What Do Babies Know?" Most notable in this article was the fact that studies of infant cognition had tripled in the past 5 years. In regard to studies of cognition and hearing, the article reported that the baby's ears have been functioning even before birth, and the newborn arrives with a whole set of auditory reactions. As early as the 1960's tests indicated that babies go to sleep faster to the recorded sound of a human heartbeat or any similarly rhythmic sound. More recent studies indicate that by the time they are born, babies already prefer female voices; within a few weeks, they recognize the sound of their mother's speech. (Friedrich, 1983, p. 55) This is but one example of the numerous research endeavors in the areas of hearing and speech. As for language, just over 120 years ago Paul Broca formalized the notion of cerebral dominance for language (Segalowitz, 1983). Yet, in the last 15 years we have seen an enormous growth in this area stemming from Eric Lenneberg's treatise, Biological Foundations of Language (1967). Segalowitz (1983) studied how language is represented in the human brain and found that each language function can be discussed with respect to its own organization within the brain. It continues to be a source of wonder that the 3-pound convoluted glob of gray tissue that controls life is capable of controlling language, speech, and emotion in humans, and that 16 science has localized the functions of the brain in both hemispheres. Blakeslee (1980) cites scientific evidence indicating that only the left hemisphere of our brain is capable of expressing its thoughts in words (verbal thoughts). The right hemisphere of the brain has its own separate train of thoughts that are nonverbal. This differentiation may not be as clear-cut as was once believed, and both controversy and research continue in this domain (see Rodda et aI., pp. 94-99). We know that there are four lobes of the brain in each cerebral hemisphere : (a) frontal, which contains the motor cortex; (b) parietal, which receives sensory input from the skin and muscles; (c) temporal, which contains nerve centers that influence speech, hearing, and emotions; and (d) occipital, which serves as the visual center of the brain. For us in the field of deafness, it is common knowledge that much of what deaf people know about their world comes to them through their eyes. This fact tells us that the occipital lobe is frequently activated. For people with normal hearing, the ability of the brain to connect auditory with visual stimuli in the temporal lobe is evident. But what about the deaf? What evidence do we have that both components-auditory and visual-are less developed in people with sensory impairments? Lenneberg (1964) stated that the ability to learn language is so deeply rooted in man that children learn it even in the face of dramatic handicaps. Congenital blindness has no obvious effect on word acquisition even though there is only a small fraction of words whose referents can be defined tactually. Congenital deafness has a devastating effect on the vocal facilitation for speech, yet presentation of written...