What is a trait of personality?

AT THE heart of all investigation of personality lies the puzzling problem of the nature of the unit or element which is the carrier of the distinctive behavior of a man. Reflexes and habits are too specific in reference, and connote constancy rather than consistency in behavior; attitudes are ill-defined, and as employed by various writers refer to determining tendencies that range in inclusiveness from the Aufgabe to the Weltanschauung; dispositions and tendencies are even less definitive. But traits, although appropriated by all manner of writers for all manner of purposes, may still be salvaged, I think, and limited in their reference to a certain definite conception of a generalized response-unit in which resides the distinctive quality of behavior that reflects personality. Foes as well as friends of the doctrine of traits will gain from a more consistent use of the term. The doctrine itself has never been explicitly stated. It is my purpose with the aid of eight criteria to define trait, and to state the logic and some of the evidence for the admission of this concept to good standing in psychology.