I am wondering about this. A lot of people measure intelligence by using IQ scores, and most people consider this to be valid.
But what they don't know is the that IQ scores work like this: They represent a sort of sum of a series of subscores in various levels of ability (be it spatial, verbal, mathematical, etc). Each of these scores measures something very different from the other scores.
Why then do we record a single IQ score? How can this be accurate? Simple. There is theorized to be a general intelligence quotient, called g, which correlates to all the various levels of ability that the IQ test is designed to measure. The subscores also do tend to correlate with each other - and it is because of this that IQ tests are held to be valid.
This is true for those who are close to the mean (which is always 'standardized' to be 100) but as you get futher and further away from this, the correlation seems to drop.
This is probably especially true for autisitcs (who have a tendency for really high performance IQ subscores and really low verbal IQ subscores) and aspies (who have a tendency for really low performance IQ subscores and really high verbal IQ subscores). So the correlation to g may also be low - perhaps aspies have normal levels of g but skewed ability in various areas (more verbal, less performances) and etc.
So aspies aren't necessarily smarter - even the ones with genius level IQs - but just better focused in a select few areas.