1) A hypothesized state inferred by observing an individual expressing a particular behavior at high rates in the absence of any identifiable external reinforcing consequences; presumably, emitting the behavior is itself reinforcing. Behavior controlled by a very thin schedule of reinforcement.

2) The control of behavior by the natural consequences the behavior itself produces. Natural consequences may be conditioned reinforcers - that is, they may be stimuli that have become important through their association with other reinforcers. For example, when society reinforces certain kinds of markings, those markings become conditioned reinforcers. Thus we become reinforced by seeing ourselves produce the kinds of pictures which have in the past been socially reinforced, even if now no one is around to notice. Our motivation to draw is then called intrinsic.