Journal of Personality and Social Psycholology,  1975 Nov;32(5):783-9

Dissimilarity and attraction: when difference makes a difference.*

Grush JE, Clore GL, Costin F

Students in 93 university classes described themselves and their instructors on personality tests measuring traits relevant (ascendancy and personal relations) and irrelevant (sociability and cautiousness) to teaching skill. Dissimilarity (instructor being higher than student) on relevant trait dimensions was hypothesized to be instrumental for student satisfaction with an instructor's role performance. When students were classified as similar or dissimilar to their instructors on the personality dimensions, those most attracted to their instructors were those dissimilar on relevant (but not irrelevant) traits. The dissimilarity finding was not an artifact of differences in skill of instructor nor of differences in students' perceptions of their instructors' traits. A three-dimensional system was devised to specify when similarity and dissimilarity should promote attraction.

* Reproduced with permission of the APA - Journal of Personality and Social Psychology