I've just found this interesting article, with a review of literature
http://findarticles.com/p/articles/mi_hb6470/is_3_21/ai_n28728468/

Quote
Carter's (1985) research on a large sample of gifted young people found that stage advancement is at best two years ahead of typically-developing peers. Comparisons of moderate and highly gifted students (Bekey & Michael, 1987) found no significant difference between groups, although both groups were able to successfully perform at least one formal operations task by age 9 or 10. In the case of formal operations, domain specificity appears to be a factor in studies reported by Berninger and Yates (1993), Keating (1991), and Marini and Case (1994), wherein transitions occurred within but not across preferred domains.

Last edited by Tallulah; 10/27/10 09:15 PM.