Synonyms – Mental deficiency, mental handicap, Mental subnormality, amentia.
In mental retardation,, there is a state of arrested development of mind from birth or early childhood.
5% of all babies born and 1 to 4% of all children in school going age are to a varying extent mentally retarded.
Grades of mental retardation –
1. Slightly retarded (high grade defectives or feeble minded subjects, morons) — These subjects lack in alertness and curiosity, are inert, passive, easily fooled, easily led into criminal acts. Their I.Q. (intelligent quotient) varies between 50 – 70. They may be rehabilitated in simple routine jobs.
2. Moderately retarded (medium grade defectives or imbeciles) – They are incapable of earning their living and protecting themselves, but they can be taught to look after themselves, to wash, dress and feed themselves. Their I.Q. varies between 30 to 50.
3. Severely retarded (low grade defectives or Idiots) – They have anatomical and physiological abnormalities. Disproportionate and stunted growth of head and limbs, neurological phenomena like hemiplegia and epileptic fit. Their I.Q. is below 30. Their life span is short. They cannot guard themselves from ordinary dangers of life, and cannot be trained upto minimum degree of satisfaction.