The Pygmalion effect is fake. The original result was driven solely by wild outliers that indicate that those students were blowing the test deliberately or that the authors were incompetent, it was buttressed by inappropriate statistics, and, in an extremely familiar pattern now for any 'cool' environmental effect in social psychology, the hundreds of replications turned in ever tinier effects and to the extent that there is any effect, it is effectively zero in the long run: http://www.rci.rutgers.edu/~jussim/Teacher%20Expectations%20...