The truth of a normative claim does not depend on its being the case that the person to whom the claim applies would be motivated under any conditions other, of course, than those in which she is moved as she ought to be. Motive is not intrinsic to ethical facts but a necessary consequence of perceiving or knowing them. The existence of motive, perhaps under certain circumstances, is at least part of what it is for a normative proposition to be true.
Obligation consists in motives raised through the use of theoretical reason.
Moral obligation concerns an observer's responses. A distinctive fact of moral obligation is that agents are thought to be accountable for violations. It is a condition of the very possibility of autonomous will that reason be purely practical by enabling a form of normative judgment that is intrinsically motivating. Rather they indicate different philosophical motivations. So someone like Locke is both an autonomist internalist and an empirical naturalist internalist, since he holds that the deliberative thinking that realizes autonomy is identical with the full use of empiricist, theoretical reason.