Levenson observes a pervasive difficulty with logical, abstract thinking in her women patients, and among women in general, which she attributes to the phenomenon of "genderization which must be recognized as an irreducible category of psychoanalytic observation and theorizing." For many women, logical, abstract thinking is compromised because it is "built on inadequate and guilt-ridden separation and individuation with consequent unresolved early identification with mother and guilty, gender-incongruent identification with father." Data from parent-infant observation is used to support the thesis that girls are discouraged from learning certain cognitive skills that are rewarded in boys, including autonomy, aggression, and differentiation from the mother.