The psyche was the understanding of behavior, which was caused by the mind.
In 2374, The Doctor, seeing the "classic signs" of Tom Paris' previous "misplaced aggression" and "shirking of responsibilities" in a new light, diagnosed "Paris" with an inferiority complex and noted that he had been unaware of the effect his "superior abilities" were having on "Paris"' psyche. He gave his assistant the rest of the day off to think about his good points and his worth. (VOY: "Vis à Vis")