Twenty-nine children with learning disabilities (LD) in grades 2 and 4 through 7 were compared with children without LD for their development of proportional structures of thought. Significantly fewer children with LD had constructed second-order logical structures necessary to act on problems using multiplicative and preproportional reasoning.…

Investigated the relationship between the development of formal operations and the formation of ego identity in adolescence. Obtained significant positive correlations between combinatorial ability and degree of identity, suggesting that high identity may facilitate the application of combinatorial operations. Found some gender differences in task…