From National Public Radio: "For as long as there's been an IQ test, there's been controversy over what it measures. Do IQ scores capture a person's intellectual capacity, which supposedly remains stable over time? Or is the Intelligent Quotient exam really an achievement test — similar to the S.A.T. — that's subject to fluctuations in scores?
The findings of a new study
add evidence to the latter theory: IQ seems to be a gauge of acquired knowledge that progresses in fits and starts."http://www.npr.org/blogs/health/2011/10/20/141511314/iq-isnt-set-in-stone-suggests-study-that-finds-big-jumps-dips-in-teens