Specifically, because operant theory (Skinner, 1953) maintained that all
behaviors are motivated by rewards (i.e., by separable consequence such as
food or money), intrinsically motivated activities were said to be ones for
which the reward was in the activity itself. Thus, researchers investigated
what task characteristics make an activity interesting. In contrast, because
learning theory (Hull, 1943) asserted that all behaviors are motivated by
physiological drives (and their derivatives), intrinsically motivated activities
were said to be ones that provided satisfaction of innate psychological needs.
Thus, researchers explored what basic needs are satisfied by intrinsically
motivated behaviors.