An enthusiastic teaching style is more important to students than what's taught, according to a recent study at Cornell University. The authors say the study casts doubt on the validity of the now-standard practice of using student evaluations to help schools make decisions about tenure and promotion.

"Student ratings are far from the bias-free indicators of instructor effectiveness and quality that many have touted them to be," conclude psychologists Wendy M. Williams and Stephen J. Ceci in the September issue of Change. In the Cornell study, Ceci taught exactly the same course on developmental psychology to two very similar classes, totaling 472 students, in fall and spring semesters. The only difference was that the second time around he lectured with more enthusiasm, varying his vocal pitch and using more hand gestures.

But that stylistic difference had a profound impact on student ratings. Given an average rating in the first course, Ceci was praised by the second group for his knowledge, accessibility, and even the quality of the textbook. The authors say they were struck by the magnitude of the effect. For example, when students were asked, "How much did you learn in this course?" the average response leapt from 2.93 to 4.05 on a 5-point scale. The authors call this difference "staggering"--especially since the final grades given in the two semesters were "virtually identical."

Anthony Greenwald, a psychologist at the University of Washington, Seattle, says the study fits in with his own research showing that high grades influence student ratings. "It serves as a healthy reminder that evaluations are sensitive to things other than the amount that students learn," he says.