The autism spectrum quotient is also known as the autism quotient or AQ. It is a numerical value expressing the degree to which a person shows traits associated with autism.
A test to measure an individual's AQ was devised by psychologist Simon Baron-Cohen and his fellow researchers at the Autism Research Centre in Cambridge. Published in 2001, the test was developed as a way of evaluating autistic traits in adults. Baron-Cohen and his colleagues hoped to use the AQ test to help determine whether autistic traits were present in an individual.
The original AQ test is only intended to be applied to adults with normal intelligence. More recently, the same organisation has produced two revised versions of the test for use in evaluating children and teenagers.
The AQ test is an ipsative or "forced choice" test - one in which the subject must choose between two options that are both desirable to some degree. The test consists of 50 statements; subjects are asked to state whether they agree or disagree with these, and to what extent. There are four response options: definitely agree or disagree and slightly agree or disagree.
The questions have been worded so that a neurotypical individual would probably agree with half the statements, while disagreeing with the rest. This makes it harder for the test to be manipulated, for example by a neurotypical subject who wished to obtain a spurious diagnosis; or by someone with autistic traits who wished to conceal them, by (for example) answering "strongly agree" to all the statements.
The statements themselves are each designed to yield information on the five domains that are most strongly associated with, or affected by, autism. These include social skills (the ability to interact appropriately with others); communication skills (the ability to exchange information and share ideas with others) imagination (for example, visualizing different situations or putting oneself in another's position); attention to detail (whether small differences or flaws are noted or overlooked, for instance); and tolerance of change/attention switching (how well a person can remove their attention from one subject and transfer it to another; also how well an individual copes with, for example, moving from the car to the house after a long journey).
For the initial trials, the AQ test was administered to a control group. The average autism spectrum quotient was in the region of 16.4, which provided the investigators with a baseline. When the AQ test was administered to a group of adults who had previously been diagnosed with AS disorders, 80 per cent of the group scored 32 or above; by contrast, only 2 per cent of the control group had an AQ of 32 or more.
The AQ test alone can't identify autism or Aspergers in adults. Although the AQ test is intended for use as a diagnostic tool, it cannot provide a firm diagnosis in isolation. The results of the test must be considered in conjunction with other data.
The AQ test was popularized by Wired magazine, which featured it alongside their cover story "The Geek Syndrome" in 2001. Further online versions have proliferated. As diagnostic tools for spotting Aspergers in adults, these have dubious merit; they may simply cause unnecessary concern and anxiety. Online AQ tests should be regarded as entertainment rather than a medical evaluation.