Intellectual disabilities (ID, formerly mental retardation) have multiple causes. For example, there are many genetic causes. Brain injuries can cause an intellectual disability. Some types of medical conditions can also affect the brain's development. These causes are discussed in another section.
These different causes mean each person's disability is unique. There is no single set of shared traits or features. For example, there are no personality traits common to people with ID. However, certain specific syndromes that cause ID have personality characteristics associated with that particular syndrome. For example, children with Williams's syndrome tend to be outgoing. However, by definition, all people with ID have limited intellectual functioning. These limitations often create some commonly observed difficulties.
One such problem is impulse control. You may recall that people with ID have trouble connecting cause and effect. This in turn causes problems with impulse control. For instance, suppose a child sees yummy, hot cookies coming out of the oven. The child wants to grab one immediately. If not controlled, this impulse will cause a nasty burn. Experience is usually a great teacher. So, most children only make this impulsive mistake once or twice. They form a connection between the hot cookie (cause) and the burn (effect). They learn to control the impulse to grab a cookie right out of the oven. However, this is not so easily learned by people with ID. This poor impulse control leads to many unpleasant consequences.
A related problem is poor frustration tolerance. When an impulse is inhibited, it requires the ability to tolerate a bit of frustration. This ability is called frustration tolerance. Frustration tolerance is an important developmental skill. It allows people to comfortably endure the small frustrations of everyday life. This in turn serves to limit the unpleasant consequences associated with impulsive behavior. Returning to the previous example, it is frustrating to inhibit the impulse to grab a cookie. However, it avoids the consequence of a nasty burn.
Frustration tolerance also enables people to build confidence. When we attempt to solve problems, our initial efforts may fail. This can be very frustrating. Without frustration tolerance, people give up. As a result, they do not put forth any effort. Clearly, if we make no effort to solve problems, we cannot develop the skills we need to solve them!
Poor frustration tolerance is not the only problem. This is coupled with many more opportunities to become frustrated. Return to the prior example of a child's impulse to grab a hot cookie. If a caregiver attempted to stop the child from grabbing the cookie, it frustrates the child. She would not readily understand her caregiver's benevolent motivation. It bears mentioning that not all people with ID become easily frustrated. This example simply illustrates that the opportunities for frustration are significantly increased.
The increased opportunities for frustration highlight the importance of frustration tolerance. People respond to frustration in different ways. Some people respond in an impulsive, stubborn, and aggressive manner. Others respond with passivity, withdrawal, and compliance. Poor frustration tolerance may cause aggression toward caregivers. It may also lead to self-injurious behavior. These behaviors are observed in some people with ID.
Another common difficulty is low self-esteem. Self-esteem naturally develops as children learn to solve problems. The ability to solve problems builds self-confidence. However, limited intellectual functioning makes it difficult to solve problems. Skillful problem solving requires sustained attention and persistence in the face of difficulty. These abilities are limited in persons with limited intellectual functioning. Thus, a low self-esteem may develop. Psychiatric disorders related to low self-esteem, such as depression, may accompany intellectual disabilities. However, many people with ID are quite happy and content. They don't exhibit problematic behavior.