Within this overall tradition, the psychologist Krutetskii (1976) has developed a concept of mathematical ability which is more fluid and less hierarchical than that discussed above. He first offers a critique of the relatively fixed views of mathematical ability stemming from the psychometric tradition in psychology. He then offers his own theory of mathematical ability based on the mental processes developed by individuals used in attacking mathematical problems. He acknowledges individual differences
In mathematical attainment, but gives great weight to the developmental and formative experiences
Of the learner in realizing his or her mathematical potential.