Do Mentally Retarded Children Truely Have Poor Memory?

Poor memory of mental retarded children is a common complain doctors hear from their parents. They complain that their child does not remember anything that they teach them, but is it really due to poor memory? The truth is that it is not due to poor memory. The problem in mentally retarded children is difficulty in understanding. Everybody, even a normal person tend to forget things easily when they don't understand them. So, same thing happens to mentally retarded children. When they don't understand, they forget. 

For example, if you tell your child that you will bring him or her a chocolate in the evening, they will remember it and wait till you come in the evening to take the chocolate. That indicated that their memory is very good. So, their memory is good, but their ability to understand is very poor.