Key points are not available for this paper at this time.
Diana T. Slaughter, Felton Earls, Bettye M. Caldwell, Early Intervention and Its Effects on Maternal and Child Development, Monographs of the Society for Research in Child Development, Vol. 48, No. 4, Early Intervention and Its Effects on Maternal and Child Development (1983), pp. 1-91
Slaughter et al. (Sat,) studied this question.