Developmental disability, once called mental retardation, is characterized by below-average intelligence or mental ability and a lack of skills necessary for day-to-day living. People with developmental disabilities can and do learn new skills, but they learn them more slowly. There are varying degrees of developmental disability, from mild to profound.
Someone with developmental disability has limitations in two areas. These areas are:
IQ (intelligence quotient) is measured by an IQ test. The average IQ is 100. A person is considered developmentally disabled if he or she has an IQ of less than 70 to 75.
Developmental disability is thought to affect about 1% of the population. Of those affected, 85% have mild intellectual disability. This means they are just a little slower than average to learn new information or skills. With the right support, most will be able to live independently.