Welcome to another day of the A to Z Challenge on autism. Today, I will discuss autism and intelligence.
First, what is intelligence? Intelligence is generally defined as a person’s overall cognitive ability across a number of domains, such as verbal comprheension, perceptual reasoning, working memory, etc., as measured by standardized IQ tets. Examples of IQ tests include the Stanford-Binet test used mostly in the U.S. and the Wechsler scales used more in Europe.
An average IQ score is 100. IQ follows the bell curve by which, the further a score deviates from average, the fewer people have this score. The standard deviation used on IQ tests is 15 on the Wechsler scales. This means that an IQ of 70, which is defined as the cut-off for intellectual disability, is two standard deviations below the norm. Approximately 2% of the population have an IQ below 70.
On IQ tests, the score is usually divided in a verbal commmponent and a non-verbal or performance component. Autistic people commonly have a gap between their verbal and non-verbal intelligence quotient. Some non-verbal autistic people show a dramatic increase in their IQ scores once they learn to type. Other people, usually diagnosed with Asperger’s Syndrome, have a high verbal IQ but a lower or even below-average non-verbal IQ.
It used to be thought that autistic people usually had a low IQ or intellectual disability. Current estimates are that approximately 40% of children with autism spectrumd isorder also have an intellectual disability. Children diagnosed with Asperger’s Syndrome by definition do not have an IQ below 70. However, some people with Asperger’s score as borderline intellectual functioning (IQ between 70 and 85) and may benefit from services for people with an intellectual disability.
IQ may be a predictor of how capable a person will be of becoming independent. However, other factors play a role too, such as adaptive functioning. Young children with Asperger’s usually do not have problems with self-help skills or adaptive funcitoning (other than that required for social interaction). However, as children mature, more problems with adaptive functioning in general may arise. I unfortunately have never had an assessment of adaptive functioning, so I don’t know how I’d score. However, people are usually surprised at my ability to use the computer but not, for example, cut up my own food or take proper care of my personal hygiene without prompting.