[1] Johns Hopkins Univ, Dept Psychol & Brain Sci, Baltimore, MD 21218 USA
[2] Kennedy Krieger Inst, Baltimore, MD USA
[3] Johns Hopkins Univ, Sch Med, Dept Neurol, Baltimore, MD 21218 USA
[4] Johns Hopkins Univ, Sch Med, Dept Pediat, Baltimore, MD 21218 USA
[5] Johns Hopkins Univ, Sch Med, Dept Educ, Baltimore, MD 21218 USA
[6] Haskins Labs Inc, New Haven, CT 06511 USA