Attributions vary in three underlying ways: locus, stability, and controllability. Locus of an attribution is the location (figuratively speaking) of the source of success or failure. If you attribute a top score on a test to your ability or to having studied hard, then the locus is internal; that is, being smart and studying are factors within you. If you attribute the score to the test's having easy questions, then the locus is external; in other words, your success is due to something outside of you. The stability of an attribution is its relative permanence. If you attribute the score to your ability, then the source of success is relatively stable—by definition, ability is a relatively lasting quality. If you attribute a top score to the effort you put in to studying, then the source of success is unstable—effort can vary and has to be renewed on each occasion or else it disappears. The controllability of an attribution is the extent to which the individual can influence it. If you attribute a top score to your effort at studying, then the source of success is relatively controllable—you can influence effort simply by deciding how much to study. But if you attribute the score to simple luck, then the source of the success is uncontrollable—there is nothing that can influence random chance.
As you might suspect, the way that these attributions combine affects students' academic motivations in major ways. It usually helps both motivation and achievement if a student attributes academic successes and failures to factors that are internal and controllable, such as effort or a choice to use particular learning strategies (Dweck, 2000). Attributing successes to factors that are internal but stable or controllable (like ability), on the other hand, is both a blessing and a curse: sometimes it can create optimism about prospects for future success (“I always do well”), but it can also lead to indifference about correcting mistakes (Dweck, 2006), or even create pessimism if a student happens not to perform at the accustomed level (“Maybe I'm not as smart as I thought”). Worst of all for academic motivation are attributions, whether stable or not, related to external factors. Believing that performance depends simply on luck (“The teacher was in a bad mood when marking”) or on excessive difficulty of material removes incentive for a student to invest in learning. All in all, then, it seems important for teachers to encourage internal, controllable attributions about success.