How can we boost IQs of "dull children"?: A late adoption study

From 5,003 files of adopted children, 65 deprived children, defined as abused and/or neglected during infancy, were strictly selected with particular reference to two criteria: ii) They were adopted between 1 and 6 years of age! and (ii) they had an IQ <86 (mean = 77, SD = 6.3) before adoption. The average IQs of adopted children in lower and higher socioeconomic status (SES) families sere 85 (SD = 17) and 98 (SD = 14.6), respectively, at adolescence (mean age 13.5 Sears). The results show (i) a significant gain in IQ dependent on the SES of the adoptive families (mean = 7.7 and mean = 19.5 IQ points in ion: and high SES? respectively), (ii) IQs after adoption are significantly correlated with IQs before adoption, and (iii) during adolescence, verbal IQs are significantly lower than performance IQs.