Course 2: Individual Learning Differences

A commonly accepted definition of intellectual disability is from the American Association on Intellectual and Developmental Disabilities (AAIDD). AAIDD defines intellectual disability as “a disability characterized by significant limitations in both intellectual functioning and in adaptive behaviour…originating during the developmental period.”

Intellectual functioning refers to general mental capacity and abilities to learn, solve problems, and reason. One common way to measure intellectual functioning is by using an IQ test.

Adaptive Behaviour

Adaptive behaviour refers to a range of practical skills people use in their everyday lives. According to the definition, these are divided into three clusters:

• Conceptual skills such as literacy, numeracy, and the ability to use money
• Social skills such as the ability to follow the norms of society, abide by the rules, and maintain personal safety
• Practical skills such as personal hygiene, occupational skills, and health care

Significant Limitations

For an individual to be diagnosed with an intellectual disability, there must be significant limitations in intellectual functioning and adaptive behaviour.

In British Columbia, an IQ of 70 or below is the determination of eligibility for adult services following school. In the US, an IQ of 70 is considered the definition of severe disability. People who score below 70 are considered to have significant limitations in intellectual functioning.

Standardized tests of intelligence are based on typically developing children with intact sensory and motor systems, and the ability to communicate verbally. Standardized tests of this nature are not able to assess the IQ of a student with complex needs and are not useful in determining learning or support needs.

There are also a number of standardized tests that are used to assess adaptive behaviour. Significant limitations in adaptive behaviour interfere with engaging in typical roles and social responsibilities.

Originating During the Developmental Period

Originating during the developmental period refers to a general time frame in which the disability originates. The definition of the developmental period varies across agencies, provinces, and countries. In British Columbia, age 19 is when an individual with a disability transitions from the Ministry for Children and Family Development supports to adult services provided through Community Living BC (CLBC). Nineteen years is the cap for the developmental period. Therefore, an injury at 20 years of age in B.C. that results in significant limitations in cognitive functioning is not an intellectual disability. It is defined as an acquired brain injury. According to the American Association on Intellectual and Developmental Disabilities (AAIDD) definition, the developmental period extends to age 22.