Plenty is doing.
"Normally, IQ is quite highly correlated with scholastic performance; and if [the Milwaukee Project] training had affected general intelligence and not just the specificity of the IQ scores, the treated and untreated groups should have differed markedly in scholastic performance. But they did not. {Despite their 30 IQ-point boost, the experimental children remained low in attainment, like their controls, at around the 10th percentile.} A reasonable interpretation of this striking result is that it was the specificity of the IQ test that had been trained up, while general intelligence remained unaffected." A.R.JENSEN, 1989, draft paper, 'Understanding g in terms of information processing.' "Infants in the inner city of Milwaukee who were considered at risk for mental retardation because their mothers had IQs of 75 or below were assigned to Experimental(E) or Control(C) groups. From a few months of age to 6 years of age, the E group was given intensive psychological intervention designed to prevent the deceleration in the rate of mental development typically seen in such children. The gains of the E group in Stanford-Binet and Wechsler IQs, as measured against the untreated C group, were considerable, peaking at about 30 IQ points at age 6, when the special intervention ended and the children entered regular school. Thereafter, the E-C difference rapidly decreased, reaching about 10 IQ points by 14 years of age. The E-C difference in IQ was not reflected in the nonsignificant E-C difference in Reading achievement scores or the questionably significant difference in Maths achievement scores, on which, by the end of the fourth grade, the mean scores for both the E and C groups were at about the 10th percentile of the normative sample. These results are most plausibly interpreted as a specific training effect of the intervention on the item content of the IQ tests without producing a corresponding change in g, the general intelligence factor common to all cognitive tests, that the IQ ordinarily reflects in the untreated population."
Disclaimer: this quote appears here only to spark discussion. It is not endorsed one way or the other. Make up your own mind. Or just refresh the page for another viewpoint. From a collection assembled by the late Chris Brand.