Expectations about self-competence and difficulty of a task to be undertaken can foster motivation and hence affect engagement, giving rise to individual differences in performance. This effect was examined in a memory task. An increase in recall performance following instructions about high competence was hypothesised; in addition, a modulating effect of instructions about easiness or difficulty of the material was expected. Two experiments were performed, in which expectations were established by giving instructions of high or low competence and easiness or difficulty of two texts: objectively, one easy, one difficult. The results showed that being given instructions about high competence raises performance if presented alone and if difficult texts are expected when the actual text is easy: the more able-more difficult effect.