The term big-fish-little-pond effect was introduced by Herbert W. Marsh and hypothesized that the abilities of students are connected with the ability of their peers in school: Thus, academic self-concepts depend not only on one's academic accomplishments but also the accomplishments of those in the school that a student attends. Consequently low- or medium-ability students might prefer to attend a low-ability school instead of a high-ability school.
Pupils can receive additional motivation from low- or medium-ability pupils in their class because their own achievements appear more significant, are more honored and they may be motivated to keep their edge over the other pupils. This is especially true for pupils with lack of self-confidence. Some parents send their children with the explicit recommendation of psychologists to schools that are known for a moderate level of proficiency.
A contrary effect is the reflected glory effect (or assimilation effect), which describes the stimulation a pupil may receive from a school with a high level of proficiency.