4. 4. CHC Theory Extensions
CHC theory currently consists of nine broad abilities (Gf, Gc, Gv, Ga, Gsm, Glr, Gs, Gq, Grw).  A review of the factor analytic research during the past decade (1993-2003) argues for a number of extensions to the CHC taxonomy.   Following Stankov’s (2000) research distinction, structural extensions reported here are classified as either internal (i.e., elaboration on the nature of existing well-estbablished broad CHC factors) or external (i.e., research that suggests new broad ability domains or domains that have been only been partially investigated).