• Morons are mild mentally retard individuals. They are educable and they can be trained to do some simple routine work. Their mental capacity is compared to children between 8-12 years old that is why they usually have poor ability to control their emotion.
• Imbeciles are moderate mentally retarded persons. They are trainable and have mental capacity of children between 3-8 yeard old. They never learn the value of money and they have a retarded physical development
• Idiots are severe/profound mentally retarded individuals. They have mental capacity of children between 2-3 years old. They do not know the dangers in life that is why, most of them die early if not in total custody of adults. They are life-time dependents. They are also physically retarded.

Mentally retarded persons have child-like mental capacity and thinking. They need close supervision and guidance, attention, love, and care because of their condition. The extremes of intelligence or exceptional children (mentally gifted and feeble minded) are usually given special education and training.