Study On Cognitive Mechanism Of Children With Developmental Dyscalculia

Developmental dyscalculia is a specific learning disability that arithmetic skills of children with dyscalculia are remarkably lower than normal level according to the age,intelligence and education.Its prevalence in the school age children is about 3%-6%.Developmental dyscalculia is a problem of developmental lag,which has significant influences on the education and living of individuals with this disability.Currently,research on dyscalculia in China is still in the beginning stage.The present study will adopt the methods of questionnaire investigation and psychological cognition study,having children with dyscalculia(including pure-dyscalculia and combined dyscalculia and dyslexia) as study objectives,to investigate the prevalence and influencing factors,behavioral characteristics and cognitive characteristics(intelligence,mathematical ability and working memory components) of children with dyscalculia,and to reveal the cognitive mechanism of dyscalculia.It could help establish foundation for biological study on dyscalculia.PartⅠEpidemic Study on Developmental DyscalculiaObjective:To explore the distribution and risk factors of it as a mental disease.Methods:Three elementary schools were selected representatively according to randomized cluster sampling methods,in which 1041 third to fifth graders were selected, children with DD were selected step by step according to the definition in DSM-Ⅳby the criteria of following checklist:The Pupil Rating Scale Revised Screening for Learning Disability,Rating scale for Basic Mathematical competences-Chinese revised,Combined Raven's Test,Dyslexia Checklist for Chinese Children,and Basic Condition Questionnaire was used.Results:37 children were diagnosed as having developmental dyscalculia only(DD-only), while 12 children were diagnosed as having developmental dyscalculia combined with developmental dyslexia(DD&RD),and the prevalence of DD-only and DD&RD were 3.55%and 1.15%respectively.On the basis of single factor analysis,multi-factor analysis was undertaken,revealed that factors those aggravated the occurrence of developmental dyscalculia included having difficulties finishing homework,and factors that prevent the occurrence of developmental dyscalculia included mother's Chinese achievement in elementary school(OR=0.255),attending music training(OR=0.178) and reading,literature training(OR=0.220),encouraging children to read widely(OR=0.307).Conclusion:Developmental dyscalculia is a developmental problem that can't be ignored, since the prevalence of it is so high.A number of factors may influence the occurrence of development dyscalculia.It is the cooperation of family,school and society that contribute to the improvement of arithmetic ability of children with development dyscalculia.PartⅡBehavior Characteristics of Children with Developmental DyscalculiaObjective:To provide foundation for the diagnosis and further research on cognitive mechanism underlying DD.Methods:37 children were diagnosed as having developmental dyscalculia only(DD-only), while 12 children were diagnosed as having developmental dyscalculia combined with developmental dyslexia(DD&RD),50 children were select as control group.PRS was used to screen learning ability of children with DD,while DCCC was used to screen reading features of them.Results:When investigated the learning ability of children with DD,we found that children with dyscalculia got lower scores in the all of subtest of PRS than children in control group, children with DD&RD got lower scores in time and orientation discrimination and social behavior subtest than that of children with DD-only,significant group effect was observed (P＜0.01).When investigated the reading ability of children with DD,we found that children with DD&RD got higher scores in 8 subtest of DCCC than children with DD-only and normal children,significant group effect was observed(P＜0.01).Group differences were observed between DD-only group and control group in the following subtest:auditory perception,comprehension ability,handwriting skill,literal expression and reading habit.Conclusion:Children with DD have behavioral deficit regarding learning ability broadly, the extent of such deficit in children with DD&RD is more serious than that in children with DD-only,which had serious influence on the school life of children with dyscalculia.PartⅢCognitive Characteristics of Children with Developmental DyscalculiaObjective:To explore the cognitive mechanism underlying DD and to provide foundation for establishing subtypes of DD and further research.Methods:Combined Raven's Test and Rating scale for Basic Mathematical competences-Chinese revised were used to investigate characteristics of intelligence and math ability respectively.The methods of forward and backward digit span task in WISC-CR were used to measure verbal working memory,Visual C++ and psychological testing software named DMDX was used to design experimental tasks to explore the working memory characteristics of children with developmental dyscalculia.Results:The results in intelligence testing showed that:the IQ scores of children with DD are lower than those of normal children significantly.The abilities of comparison and reasoning,serial relationship and abstract reasoning of children with DD-only and of children with DD&RD are lower than that of normal children.The ability of analogical comparison of children with DD-only is lower than that of normal children,all these differences reached significant level(P＜0.05).The results in study on mathematical abilities of children with developmental dyscalculia revealed that the performances on the all of subtests except digit junction of children with DD-only and of children with DD&RD are worse than that of normal children,children with DD&RD got lower scores than children with DD-only got in division subtest,group differences reached significant level(P＜0.01).Study on working memory of children with DD revealed that there were no group differences between DD group and control group in verbal working memory test.There were group differences between DD-only group and it's control group in visual matrix span task and Corsi span task(P＜0.05).The scores in backward digit span task of children with DD-only were lower than that of normal children,a significant group effect was observed (P＜0.01).The reaction time in letter naming task,numerical Stroop effect of children with DD-only were longer than that of normal children,and the accuracies in objects inhibition task and word-color Stroop task(incongruous condition) of children with DD-only were lower than that of normal children,and the accuracies in word-color Stroop task of children with DD&RD were lower than that of normal children,group effects were observed (P＜0.05).Analysis of covariance was performed to examine purify effect of inhibition, there is group differences between DD-only group and control group in the reaction time of numerical stroop task when that of magnitude counting was controlled(p＜0.05),but this was not the case for objects inhibition and objects naming(p＞0.05).The reaction time in spatial task,verbal task of children with DD-only were longer than that of normal children, the accuracies in verbal task,verbal-spatial bound task,verbal-spatial separate task of children with DD-only were smaller than those of normal children,all of group difference mention above reached significant level(p＜0.05).Conclusion:The intelligence levels of children with DD are lower than those of normal children,and the intelligence structures of former are not balance;children with DD existed extensive deficits in mathematical abilities and working memory,developmental dyscalculia is the result of general cognitive deficits.