Woking memory and short term memory processes in children with normal hearing

Because cognitive processes have close links to education, and hearing loss is perceived as a natural experiment, efforts by practitioners and basic scientists for understanding the nature of cognitive functioning of children with hearing loss have more than 100 years of historical background. In this continuum, research about the cognitive processes of children with hearing loss had mostly focused on intelligence, but relatively not much enough studies were held on dynamic processes such as working memory (WM) and short-term memory (STM) which are considered to be in the centre of- and central to information processing . In general literature, few studies had drawn attention on the relationships of audiological and educational characteristics and temporary memory processes of children with hearing loss. In Turkey, there had been only one study with a very limited sample concerning the issue up to the present.The purpose of the study is two-fold. The first one is to determine the group differences between children with hearing loss and their normally hearing peers as well as between subgroups of children with hearing loss in terms of the performance on WM and STM measures when age and IQ are controlled. The second purpose is to specify the demographic, cognitive, audiological, and educational predictors of the measures of WM and STM for both groups of children. The total sample [N = 223] consisted of normally hearing children [n = 103] and children with hearing loss [n = 120] from three different educational settings in Eskişehir, Turkey: Children from (1) Education and Research Centre for Hearing Impaired Children, namely İÇEM [n = 62], (2) Mainstream settings [n = 27], (3) School for the Deaf [n = 32]. The measures were WISC-R Performance subscales for performance IQ, sentence-digit span and digit span-backward tasks for verbal WM, paper folding task for visuo-spatial WM, and digit span-forward task for verbal STM.The main group and subgroup differences were determined by multivariate analysis of covariance (MANCOVA) which also facilitated the control of age and IQ, and predictors of WM and STM measures were specified by multiple regression analysis. In common, MANCOVA results revealed no significant performance differences between main groups for visuo-spatial domain, but significant differences between main groups and subgroups for verbal tasks. Following comparisons resulted in significant differences with respect to verbal tasks: (1) Normally hearing children performed better than children with hearing loss. (2) Children of both İÇEM and mainstream settings performed better than the children who attend the School for the Deaf. (3) Being less distinctive in hearing loss group, children of older ages performed better than younger ones. (4) Children with hearing loss who received parent guidance and pre-school education performed better than the ones who did not. (5) Children who use cochlear implant and hearing aid effectively performed better than children who use such aids ineffectively. No significant differences were observed for gender in both groups. The degree and age at onset of hearing loss made no difference in any performances, and possible explanations were given. As for the second purpose of the study, multiple regression analysis revealed that age and IQ were the best predictors of WM and STM performance in children with normal hearing. For children with hearing loss, in addition to mentioned variables, age at implementation and duration of parent guidance made significant contribution in certain degrees especially for explaining the variance in verbal tasks.Results were consistent with the literature which claimed that communicating in oral language, using assistive devices effectively, and receiving early intervention (parent guidance and pre-school education) support cognitive processes ?WM and STM performances in this study- of children with hearing loss. The findings were discussed in detail.Key Words: Children with normal development, cognitive processes, hearing impaired children, hearing loss, short term memory, working memory.