Pattern recognition is an interesting way to describe what is being measured. I've always heard that IQ tests are really good at predicting the ability to understand complexity, or perform complex tasks; such as in the way the military has traditionally used intelligence tests to match recruits. I wonder if being really good at advanced math just means 'really good at pattern recognition'.

Anyway, I saw an interesting theory once that suggested IQ simply measures motivation and highly motivated people will tend to do better on standardized tests as well as more generally in life.