Final answer:
Jung identified extraversion and introversion as two approaches towards life, and sensation as a function of the psyche. Rational thinking is part of how the mind operates but not considered a separate Jungian function; it aligns with the 'thinking' aspect of the MBTI.
Step-by-step explanation:
According to Carl Jung, rational thinking is not one of the functions of the psyche but rather an aspect of the way the mind operates. Jung's primary contributions to personality psychology were the concepts of extraversion and introversion, which describe two attitudes or approaches toward life. If you are extraverted, you are energized by being outgoing and socially oriented, and if you are introverted, you may be reserved or socially active, but you derive energy from your inner psychic activity.
Jung also put forth functions of the psyche that include sensation, along with thinking, feeling, and intuition. These concepts are integrated into modern assessments like the Myers-Briggs Type Indicator (MBTI), which evaluates psychological preferences in how people perceive the world and make decisions. Rational thinking itself is not categorized as a function by Jung but is associated with either 'thinking' or 'feeling', as part of the four dichotomies used in personality typologies inspired by his work.