[jessriedel]

Reply to scott_s: In that article, note that the study addressed the effect of pre-school on strongly disadvantaged children: "Only disadvantaged children living in adverse circumstances who had low IQ scores and a low index of family socioeconomic status were eligible to participate in the Perry program."

[scott_s]

Right, it's not an experiment for the conditions under discussion. It is, however, an experiment which demonstrates the importance of early childhood environment.