Visual Spatial Enhancements In Congenital Deaf And Signers

Visual Spatial Enhancements in Congenital Deaf and Signers

Abstract

This paper examines the concept of compensatory plasticity for deaf individuals by reviewing background research on reorganization of visual processing. Early work in visual processing and cognition noted neutral to worse development compared to hearing populations. Much of this research is flawed due to researchers using heterogeneous populations of deaf individuals, not drawing a line between those profoundly and those with varying degrees of hearing loss. By collecting research based only on those populations that are congenitally deaf and have acquired a sign language (native signers), enhancements found in visual attention are highlighted. Finally, by taking the results of these studies, this paper shows the implications for this reorganization of visual processing in the education of the deaf and policies that may help maintain attention skills.

Cognitive psychology has long been interested in the development of human sensory inputs to the brain because of the potential that information has to say about our abilities and how we acquire information about our world. One of the many methods of studying those inputs is by examining the results of sensory deprivation on one or more of the modalities and the effect on the remaining senses. Early work in this field has spurred the theory that when humans become deprived of one or more of the senses, those intact become sharper. These studies are supported by the idea of brain plasticity; the ability to reorganize the brain in order to achieve functional improvement after brain damage (Bach-y-Rita, 2003). It was found that in blind individuals, reorganization occurred within the cognitive structure to overdevelop advanced cutaneous senses. Bach-y-Rita found that when brain damage occurred to one part of the brain, other parts of the brain took over the functionality served by the lossed mechanism. The popularity of this idea carried with it the prospect of better rehabilitation systems for those with brain damage. Following this, it has been speculated that deaf individuals might also see better (Myklebust 1964). This is underlined by the deaf individual's lack of auditory input and the use of a visual-manual language requiring exercise of visual attention processes on a daily level. Extensive research on how deafness affects different aspects of visual processing reveal conflicting works which suggests that only particular parts of the visual system are affected. (Dye)

Effects of Auditory Deprivation on Cognition

Previous to theories of compensatory plasticity, early work in the 1950s indicated that deafness impaired or did little to change cognitive abilities. Deafness was apparently responsible for reduced abilities in abstract reasoning, analogy, memory, and symbolic thinking (myklebust and Levine [from colmenero article]). More importantly these studies failed to show any enhancement of visual attentional abilities. The results may prove to be problematic when the heterogenous background of the deaf participants is taken into consideration. Colmenero and colleagues point out, the characteristics of the samples varied in their amount of hearing loss, etiology, and onset of deafness. There are large differences and confounding variables between an individual who has had some hearing loss and congenital deafness. The introduction to the structure of a spoken language can mean vastly different effects on the development of a deaf child compared to one that has never heard how spoken language operates.

However we cannot completely disregard these assessments simply due to methodological errors since there seems to be evidence from deaf education that supports these early views. There is a wide amount of reports that deaf students fall behind in mathematics where problems test for analogy, abstract reasoning, and inductive thinking (Traxler, Blatto-Vallee, Zarfaty, Passig). Zarfaty reports in his survey of mathematical competence, that deaf pupils in England between the ages 8 and 12 were 2 standard deviations below the mean scores and similar findings were reported across Europe (Zarfaty 2004). On the same vein, Taxler found that among SAT scores (even when standardized to take into account deaf students) deaf students maintained these results. With the exception of Passig, these studies indicate that causation is not a spatial or visual problem. They reflect inadequate sign language interpretation that fail to meet the needs of the students from an early age and onward (Marschark 2005). They do not indicate that there is some visual incompetency preventing students from acquiring basic skills.

Along that thought, Passig was able to demonstrate that by using virtual reality 3D games he could achieve better inductive reasoning skills with shapes for deaf children (Passig 2000). He showed deaf and hard of hearing students a series of 3 dimensional shapes which lead to reasoned conclusions about the next structure. The idea is that because of the association with a visual spatial language, the presentation of problems in using space will elicit stronger results. The experiment was done using virtual reality headsets and was compared with a similar population using a 2 dimensional tv-set game to isolate the effect caused by space. Results from this experiment showed that deaf individuals were able to achieve the same inductive scores as hearing subjects and that this process of linking visual imaging with 3 dimensional tasks improved their scores overall in this form of abstract thinking. This shows that there is no binding limitation on the acquisition of abstract thinking because of this deafness. This also suggests that there may be more than one method of teaching that should be employed when educating deaf students. More importantly the research mentioned previously to this illuminates that "teachers are typically unfamiliar with the implications of early hearing loss..." and many translators are not trained to be aware of the visual cognitions within their students (Marschark 2005). Because of the serious role that the visual system plays in acquiring information, there needs to be a thorough understanding about how deafness and sign language poses learning challenges to the Deaf community. Any differences need to be noted and evaluated while developing alternative techniques for schools.

A large amount of literature has accumulated documenting the compensatory changes in visual attention and peripheral perception