Final answer:
Carl Jung is credited with dividing behavior into the two attitudes of introvert and extrovert, which are key elements in the study of personality psychology.
Step-by-step explanation:
The psychologist who divided behavior into two attitudes, introvert and extrovert, was Carl Jung. Jung's concepts of extroversion and introversion are considered some of his most significant contributions to personality psychology, influencing various models of personality. Extroverts are typically outgoing and gain energy from social interaction, whereas introverts may be quiet or socially active but draw energy from within themselves.
Jung's view of extroverted and introverted types has had a lasting impact and even serves as the basis for instruments like the Myers-Briggs Type Indicator (MBTI). It relates to the broader understanding of personality development and traits in the field of psychology.