In the Autism-Spectrum Quotient test, the subject is confronted with fifty statements such as:
I don’t particularly enjoy reading fiction.
I prefer to do things the same way over and over again.
and is asked whether they
- definitely agree,
- slightly agree,
- slightly disagree, or
- definitely disagree
with them. There is no neutral option.
The test is scored as follows: If the subject agrees with an “autistic” statement, they score a point. The same applies, if they disagree with a “non-autistic” statement. There is no distinction between slightly and definitely agreeing (or disagreeing).
I would expect that this test design (no neutral option, no distinction between slight and strong tendencies) leads to an amplification of small effects, such as interpretation of the question, slight tendencies, priming, chance, and so on. While I acknowledge that this effect may be desired in customer surveys and similar, it seems problematic to me in a test for the purposes of diagnosis and epidemology (such as this test). For example, I would expect that people who are already diagnosed with autism (and know this) or people with clichéically autistic interests like mathematics are more likely to tend for the more autistic option – even if their actual stance on the question in neutral.
Now, I am a layman and I acknowledge that designing such a test is not easy, as one has to account for several effects. Hence I wonder: What are the justifications for such a test design, in particular in light of its applications (diagnosis and epidemology) and my above criticism? The paper introducing the test does not provide any citations or reasons for this, at least not in those sections where I would expect it.