About 87 per cent of people with mental retardation will only be a little slower than average in learning new information and skills. When they are children, their limitations may not be obvious. They may not even be diagnosed as having mental retardation until they get to school.

As they become adults, many people with mild retardation can live independently. Other people may not even consider them as having mental retardation.

The remaining 13 per cent of people with mental retardation score below 50 on IQ tests. These people will have more difficulty in school, at home, and in the community. A person with more severe retardation will need more intensive support during his or her entire life. Every child with mental retardation is able to learn, develop, and grow. With help, all children with mental retardation can live a satisfying life.

Mental retardation is diagnosed by looking at two main things:

. the ability of a person’s brain to learn, think, solve problems, and make sense of the world (called IQ or intellectual functioning); and

. whether the person has the skills he or she needs to live independently (called adaptive behaviour, or adaptive functioning).

Intellectual functioning, or IQ, is usually measured by a test called an IQ test. The average score is 100. People scoring below 70 to 75 are thought to have mental retardation.

To measure adaptive behaviour, professionals look at what a child can do in comparison to other children of his or her age. Certain skills are important to adaptive behavior. These are:

. daily living skills, such as getting dressed, going to the bathroom, and feeding one’s self;

. communication skills, such as understanding what is said and being able to answer;

. social skills with peers, family members, adults, and others.