[1] St Christophers Hosp Children, Philadelphia, PA 19134 USA
[2] Cincinnati Childrens Hosp Med Ctr, Cincinnati, OH 45229 USA
[3] Univ Illinois, Dept Psychol, Chicago, IL 60680 USA
[4] Yale Univ, Sch Med, Dept Pediat, New Haven, CT 06520 USA
[5] New Haven Publ Sch, Social Dev Dept, New Haven, CT USA