University of Illinois Extension

Mental Retardation

According to the American Association on Mental Deficiency, mental retardation is defined as subaverage general intellectual functioning that originates during the developmental period (prenatal to 16 years) and is associated with impairment in adaptive behavior.

Classification of Mental Retardation

There are many degrees of mental retardation. Persons who are severely retarded are able to learn only the most basic self-care skills. Those who are mildly retarded are able to learn so much that, as adults, some are no longer identified as being retarded. Three common classifications used include:

Mildly (Educable) -- Mental Age 8-12; learn to approximately 6th grade level.

Moderately (Trainable) -- Mental Age 5-8; cannot learn academic subjects in school.

Severely/Profoundly -- Many require life-long care and supervision and are often confined to institutions.


Not all the causes of mental retardation are known; however, more than 200 have been identified, and many others are suspected. The known causes can be placed into five categories:

  • Genetic Irregularities -- for example x-ray exposure, incompatibility of genes inherited from parents, Rh blood factor incompatibility, Down's Syndrome, error in metabolism, or recessive genetic traits.

  • Pregnancy Complications -- for example poor nutrition, German measles, tumors, glandular disorders, infections, exposure to toxic agents, or radiation.

  • Birth Problems -- for example premature birth, too rapid birth, prolonged birth, or any circumstance that reduces the oxygen supply to the infant's brain.

  • Post Birth Situations -- for example childhood diseases, especially in the very young (chicken pox,measles, meningitis, whooping cough); high fevers, severe injuries to the brain, lack of certain chemicals in the blood, or glandular imbalance.

  • Environmental Factors -- for example being born and reared in a deprived environment where there is little opportunity to learn; or serious emotional problems.


A mentally retarded person is slow to learn and may be slow or limited in the development of physical skills. Additionally, physical handicaps may be present, such as speech impairments, visual impairments, hearing defects, or epilepsy. Reminder: Because these secondary handicapping conditions are common among people with mental retardation, this does not mean that individuals who have a speech impairment or epilepsy are mentally retarded.

Help For Leaders

It is often thought that it takes a certain kind of person or an individual with special education to work with people who are retarded. The fact is that anyone who is patient and kind and who has a sincere interest in working with people can be successful. As a volunteer, you can contribute greatly to the happiness and accomplishments of individuals who have mental retardation.

  • One of the most important things to remember when teaching an individual with mental retardation is to break down the skill or project being taught into small tasks. This is called task analysis. A woodworking project provides a good example. During the first meeting, the 4-H club decided to make a pen-and-pencil holder for a Father's Day gift. A break/down of this project follows:

    • 2nd meeting -- located 10" on a ruler and marked a line on the board to be cut to the 10 mark.
    • 3rd meeting -- sawed the board.
    • 4th meeting -- sanded the board.
    • 5th meeting -- stained the board.
    • 6th meeting -- drilled two holes in the board.
    • 7th meeting -- screwed the pen and pencil holders to the board.
    • 8th meeting -- gift wrapped the finished project.

  • If an individual is not successful at completing a task it may be that the task being taught is not broken down far enough. Give simple step-by-step directions, and repeat instructions to be sure the 4-H member understands. Task analysis will help not only the 4-H'er, but it will also help the leader be well-organized and successful.
  • Establish realistic, attainable goals, and allow plenty of time for achieving them. It may take several months to teach a new skill.
  • Concentrate on concrete ideas and skills. Children have trouble with abstract concepts.
  • Be patient, persistent, and consistent.
  • Provide warmth and acceptance. Recognize each individual's potential to grow, learn, and develop.
  • Promote a sense of security through a smile or by providing a word of praise.
  • Demonstrate. Showing is often more effective than telling. Use a combination of the two.
  • "Tell me something a hundred times, and I may still not fully understand what you want me to do. Show me what you mean, demonstrate clearly and slowly, just once or twice and I'll be close to the goal. But do it with me, put your hand on mine and guide me through it, and I'll make it."

    - Author Unknown


National Association for Down's Syndrome
P.O. Box 4542
Oak Brook, IL 60522
(630) 325-9112

The Arc
(a national organization on mental retardation)