Here's one source I've found:
Dey, Eric L. COLLEGE IMPACT AND STUDENT LIBERALISM REVISITED: THE EFFECT OF STUDENT PEERS. ASHE 1988 ANNUAL MEETING PAPER. 5 Oct 1988. 28 p. (ED303066)
In this study, student liberalism is examined longitudinally to determine whether it changes as the result of being exposed to different educational environments. The effect of college on liberalism and the relative efficacy of different measures of the college environment are also addressed. The main focus is on the effect of student peers. Data were drawn from the 1983 Cooperative Institutional Research Program survey sponsored by the American Council on Education and the University of California at Los Angeles Higher Education Research Institute. Results indicate that the effect that college has upon liberalism appears to be due to socialization effects. Effects commonly attributed to the educational process may in fact be due to social forces that exist outside of college, suggesting that many of the findings related to affective student outcomes may need to be reexamined. While it is possible that changes in liberalism are due to cognitive or psychodynamic changes in students, these results indicate that involvement in different social systems affects liberalism differently. Colleges may not directly affect student values, yet bring students of different values together. Instead of developing and promoting values among students, colleges may simply serve as forums that reinforce generally held social values. Researchers may need to try to integrate more proximal measures of student experiences. By relying on structural characteristics to measure the college environment, they are adopting an imprecise frame of reference for interpretation.
It is concluded that while college promotes liberalism, the effect is neither large nor universal, and college may now have a moderating rather than liberalizing effect. Contains 28 references. (SM)

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