The Pygmalion effect

In 1968, Robert Rosenthal and Lenore Jacobson reported the Pygmalion effect, and named it after Pygmalion, a play by George Bernard Shaw.  Students at a single California elementary school were given a disguised IQ test. Teachers were then told the names of some of the students, 20% chosen at random, could be ''spurters'' that year and outperformed their classmates. The actual scores of the students were not disclosed to the teachers.