The prepubescent children of days gone by have given way to a cooler kid — the tween — who aspires to teenhood but is not quite there yet. …Retailers know tweens are a hot market for clothes, music and entertainment. But now psychologists and behavioral researchers are beginning to study tweens, too. They say tweens are a complicated lot, still forming their personalities, and are torn between family and BFFs, between fitting in and learning how to be an individual.
