Cognitive Differences Between Congenitally and Adventitiously Blind Individuals.

It is apparent from the historical perspective regarding the theories of cognitive development and the cognitive functioning of individuals with visual impairments, that sight plays a major role in the development of certain cognitive processes. However, the affects of visual impairment on cognitive development remain to be at issue. Since sight seems to be highly integral in cognitive development beginning in the early stages of physical development, about the sixth month of life, and then begins to diminish in importance as verbal communication develops around eighteen months, then it should stand to reason that significant visual impairment or blindness occurring prior to this time would adversely impact an individual's cognitive development. Conversely, the occurrence of visual impairment or blindness after this critical period of development would have less of an impact. Cognitive theorists have proposed that visually impaired or blind persons may have developed different cognitive pathways to acquire, process, and accommodate sensory information. As a result, visually impaired or blind (VI/B) persons may "think differently" than sighted individuals. The present study was designed to address these issues as they relate to cognitive and neuropsychological development at various stages of growth and to examine possible differences in neuropsychological functioning dependent on the level of visual functioning a person retains; e.g. both the issues of age at onset and degree of impairment. It was also designed to study the possible interaction effects of degree of impairment with the age of onset. Findings indicated that the only differences in cognitive functioning appear to be related to age of onset and not the level of visual impairment. The findings further suggested that congenitally blind individuals have indeed developed alternate methods of cognitively processing nonverbal, abstract, or complex information, especially information involving a high degree of spatial orientation. Implications of this study may influence the educational methods used to teach congenitally blind individuals in order to reinforce these alternate pathways and facilitate more effective means of negotiating in a sighted environment.