Which Swiss psychologist is synonymous with the concepts of introvert and extrovert personalities?

The story behind the answer

Carl Jung is correct. The Swiss founder of analytical psychology coined the terms introversion and extraversion to describe whether a person’s psychic energy is directed inward (reflection, solitude) or outward (social engagement, action). He combined these “attitudes” with four functions—thinking, feeling, sensation, and intuition—to outline different personality types.

Jung’s ideas powerfully influenced modern personality theory and inspired tools like the Myers-Briggs Type Indicator (though MBTI isn’t the same as Jung’s original model). To avoid confusion: Jean Piaget studied children’s cognitive development, Hermann Rorschach created the inkblot test, and Alice Miller wrote on childhood trauma. Memory tip: Think “Jung’s two doors”—INtrovert looks IN, EXtrovert looks EXternal—both part of Jung’s framework.