“…Each of these approaches to defining an RD group implicitly assumes that RD is a relatively homogeneous disorder, at least in terms of its phenotypic presentation. Yet, current research, as well as a perusal of studies identifying children with RD, supports the notion of RD as a heterogeneous disorder (Anderson, 1992;Delamater, Lahey, & Drake, 1981; Doehring & Hoshko, 1977;Finucci, Isaacs, Whitehouse, & Childs, 1983;Flynn & Deering, 1989;Korhonen, 1991;Lubs et al, 1988;Njiokiktjien, 1994;Smith, Pennington, Kimberling, & Ing, 1990) comprising subgroups of children characterized by different patterns of cognitive and information processing.…”