Developmental Characteristics Of Quantitative Representation In 6-18 Years Old Children With Mild To Moderate Mental Retardation

Objective : Mastering the concept of number should be based on the magnitude representation.In the early stage of psychological development,normal children will establish two magnitude representation systems:the accurate estimation to small numbers(1-3)and the approximate estimation to large numbers(7-9),and their magnitude representation to non-symbolic numbers is prior to symbolic numbers.To test whether children with intellectual disabilities have the same magnitude representation characteristics as normal children,and whether the magnitude representation ability of children with intellectual disabilities is affected by intelligence and age,we conducted two studies.Methods:60 children(age from 6 to 18)with mild or moderate intellectual disabilities were selected to finish two tasks : 0-10 numbers line estimation task and non-symbolic numbers/symbolic numbers magnitude comparison task.According to intelligence and age,60 children were divided into mild and moderate intellectual disabilities group or lower age group and higher age group,each group 30 children,and the accuracy of task performed by child was measured.Results :(1)In the numbers line estimation task,the accuracy of the small numbers estimation from children with intellectual disabilities was significantly higher than the large numbers estimation,the accuracy of number estimation from children with mild intellectual disabilities was significantly higher than those with moderate intellectual disabilities in two types of the numbers estimation,and there was no significant difference in the accuracy of estimation for two types of numbers between the lower and higher age group children with intellectual disabilities;(2)In the non-symbolic numbers/symbolic numbers magnitude comparison task,the accuracy of non-symbolic numbers from children with intellectual disabilities was significantly higher than the symbolic numbers,the accuracy of children with mild intellectual disabilities was significantly higher than those with moderate intellectual disabilities in two types numbers magnitude comparison task,and there was no significant difference in the accuracy of two types numbers magnitude comparison task between the lower and higher age group children with intellectual disabilities.Conclusion: children with intellectual disabilities have the same characteristics of the magnitude representation as normal children,ie,the accurate estimation to the small numbers(1-3)and the approximate estimation to the large numbers(7-9),and their magnitude representation to non-symbolic numbers is prior to symbolic numbers.Intelligence is an important factor which affect the magnitude representation ability of children with intellectual disabilities,while age is not,of which suggesting the irremediability of intellectual disabilities.