Psychology · Ch 1 — Variations in Psychological Attributes
Intellectual Deficiency
Intellectual Deficiency
Intellectual Deficiency
At the opposite end of the spectrum from giftedness lies intellectual deficiency. While some children learn with exceptional ease, others struggle enormously, even with very simple skills. Children who show this kind of intellectual deficiency are termed intellectually disabled.
There is wide variation among individuals who are intellectually disabled. The American Association on Mental Deficiency (AAMD) defines intellectual disability as “significantly sub-average general intellectual functioning existing concurrently with deficits in adaptive behaviour and manifested during the developmental period.” This definition highlights three essential features.
The three basic features of intellectual disability
- Significantly sub-average intellectual functioning. A person must have an IQ below 70 to be considered sub-average in intelligence. The average IQ in the general population is 100.
- Deficits in adaptive behaviour. Adaptive behaviour refers to a person’s capacity to be independent and deal effectively with their environment. This includes everyday life skills like self-care, communication, and social interaction.
- Onset during the developmental period. The deficits must appear between birth and 18 years of age. This distinguishes intellectual disability from cognitive impairments that may result from injury or illness later in life.
Levels of intellectual disability
The severity of intellectual disability is classified by IQ range. The table below shows the standard categories.
| Level | IQ Range |
|---|---|
| Mild | 55 to approximately 70 |
| Moderate | 35–40 to approximately 50–55 |
| Severe | 20–25 to approximately 35–40 |
| Profound | Below 20–25 |
What each level means in practical terms
People with mild intellectual disability develop more slowly than their peers, but they can function quite independently. They are capable of holding jobs and raising families.
As the level of disability increases, difficulties become more strongly marked. Individuals with moderate disability lag behind their peers in language and motor skills. With training, they can learn self-care, simple social skills, and basic communication. However, they need a moderate degree of supervision in everyday tasks. …