What Self-Determination Theory says
Self-Determination Theory (SDT) was developed by psychologists Edward Deci and Richard Ryan, who argued that everyone has three basic psychological needs -- autonomy, competence, and relatedness -- and that the more these needs are met, the more autonomous and sustainable a person's motivation becomes. The six-stage continuum above comes from one of SDT's sub-theories, Organismic Integration Theory, which describes how thoroughly a motivation has been internalized.
Not all extrinsic motivation is equal, and autonomy can be built
It's common to lump motivation into just "intrinsic" and "extrinsic," but SDT argues extrinsic motivation itself spans several stages depending on how much a person has genuinely accepted the reason behind it -- a goal followed only under external pressure (external regulation) behaves very differently, in terms of persistence and satisfaction, than the same goal pursued because its value has been personally accepted (identified or integrated regulation). Creating some room for personal choice within a task, or finding your own reason a required task matters, is described as a practical way to shift motivation from external regulation toward identified regulation.
Frequently Asked Questions
Is intrinsic motivation the only good kind?
No. Plenty of life's necessary activities aren't inherently interesting, and identified or integrated regulation -- autonomous forms of extrinsic motivation -- can sustain satisfying, consistent behavior just as well in those cases.
Can offering a reward actually reduce intrinsic motivation?
Some SDT research has found exactly that: adding an external reward to an activity someone was already doing purely out of interest can reframe the activity as a means to the reward, reducing intrinsic motivation for it. That said, the outcome can vary depending on the type of reward and the context.