Subjects' attitudes regarding issues were shown to become more extreme (rather than more moderate) after the presentation of conflicting evidence in a study by Lord, Ross, and Lepper (1979). However, this study had many methodological flaws, such as floor and ceiling effects in the attitude measurement scale, and the use of only self-report data on attitude changes. A recent study by Kuhn and Leo (1996) further examined the "attitude polarization" phenomenon.

In this study's 'evidence' condition, subjects were given a 13 point pre-test opinion scale asking them to assess their attitude towards capital punishment. The subjects then were given arguments for and against capital punishment. After the presentation of evidence, the subjects filled out a post-test identical to the pre-test, and a measure of their self-perceived attitude change; the subjects were post-tested again two weeks later. (The pre- and post-tests are direct measures of attitude change, in contrast to the self-reported attitude change measure).

For subjects in the "evidence" condition, 30% reported having more extreme attitudes. However, the direct comparison of pre- and post-test scores did not differ significantly from zero. Of the 6 subjects whose attitudes did change, 4 changed from a near-neutral or neutral attitude rating to a moderate position. Two of these subjects' reported attitude change consistent with the pre-test post-test change; however, the other two subjects' self-reports stated no attitude change occurred. The final 2 subjects' scores both increased from moderate to extreme ratings, and their self-reports reflected this change.

The results of this study showed that polarization of attitudes is not a common result of exposure to mixed evidence, although this effect is present for a relatively small number of people. Self-reported attitude change was also more common than directly-assessed attitude change. Finally, attitude polarization should be considered separately from attitude change from a near-neutral to more moderate position (labeled "articulating a position" by the authors of the study).

References

• Kuhn, D., and Lao, J. (1996). Effects of evidence on attitudes: is polarization the norm? Psychological Science, v7. pp. 115-20.

• Lord, C.G., Ross, L., and Lepper, M.R. (1979). Biased assimilation and attitude polarization: the effects of prior theories on subsequently considered evidence. Journal of Personality and Social Psychology, v37. pp. 2098-2109.

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