I also think Dr. Ruf is quite obviously wrong, but I'd be interested to know the basis of her opinion, if it's more than just a hunch. Perhaps she's seen evidence that practice on particular tasks can boost performance on specific tasks on one type of test (for example, the types of matrix operations on the WISC) without having any effect on the magical
g, as extrapolated from measurements by other tests.
Of course, the fact that one can presumably prep for or affect just a specific test doesn't mean at all that one can't raise one's intelligence through training. Objections to the idea seem to usually boil down to a claimed lack of evidence, just as there is a complete lack of evidence that it doesn't work.
The raised-by-wild-dogs example is often trotted out in these discussions, to show as a threshold matter that training can boost general intelligence; I've done it myself. Then someone may raise in counterpoint that the need for a threshold level of environment/"nurture" doesn't mean that benefits from enhanced nurture extend throughout the whole continuum of intelligence. A counterargument to
that, of course, is that there's no reason to suppose that training effects are simply truncated at any point, and there's evidence that intelligence can be increased in various ways even for people above the mean. Then someone may cite a study showing a decrease in training effect with lapse of time, someone else cites to an inapposite twin study on effects of living with bright mothers, and the whole mess degenerates into petty bickering.
At least that's the way I've seen it go down.
It's interesting to note the extent to which crystallized intelligence can affect scores on modern IQ tests. Are those crystallization-heavy submeasures not meant to test
g at all? And I seem to remember that there is some correlation between crystallized and fluid intelligence.
