Key points are not available for this paper at this time.
Robert B. McCall, Mark I. Appelbaum, Pamela S. Hogarty, Developmental Changes in Mental Performance, Monographs of the Society for Research in Child Development, Vol. 38, No. 3, Developmental Changes in Mental Performance (Jun., 1973), pp. 1-84
McCall et al. (Fri,) studied this question.