Pygmalion in the Classroom is a 1968 book by Robert Rosenthal and Lenore Jacobson about the effects of teacher expectation on first and second grade student performance.

Soon after Pygmalion's publication, Robert L. Thorndike, an educational psychologist, criticized the study and demonstrated that the instrument used to assess the children's IQ scores was seriously flawed.

[2] For example, the average reasoning IQ score for the children in one regular class was in the mentally disabled range, which, given the circumstances, is impossible.

"[2] Rosenthal countered that "even if the initial test results were faulty, that didn’t invalidate the subsequent increase, as measured by the same test,"[3] although with initial IQ scores in the mentally disabled range the observed change at the conclusion of the study is more likely to reflect regression-to-the-mean effects than the effect of teacher expectations.

"Most studies using product measures found no expectancy advantage for the experimental group, but most studies using process measures did show teachers to be treating the experimental group more favorably or appropriately than they were treating the control group...because teachers did not adopt the expectations that the experimenters were attempting to induce, and/or because the teachers were aware of the nature of the experiment.