Differential impact of causal and statistical evidence in counteracting belief perseverance: Changing prior beliefs about Acquired Immune Deficiency Syndrome
Slusher, Morgan Paul
Anderson, C. A.
Doctor of Philosophy
Research on belief perseverance--the finding that people cling to initial beliefs to an unwarranted extent--has demonstrated that a belief persists to the extent that there are more explanations available to the believer to support the original belief than to support alternative beliefs. Thus, explanatory evidence that supports an alternative target belief may be more effective in changing prior beliefs than statistical evidence. In an experiment testing this hypothesis, subjects read explanatory (biological) information and/or statistical (epidemiological) information supporting the belief that Acquired Immune Deficiency Syndrome (AIDS) cannot be spread by casual contact. Subjects' beliefs on this issue were assessed before and after reading this information. Subjects also evaluated the evidence they read. Finally, the availability of explanations supporting the target belief was assessed. Results indicated that: (1) explanatory evidence produced significant belief change, whereas statistical evidence did not; (2) evaluations of evidence were biased in accord with subjects' initial beliefs; (3) information polarized attitudes, although attitudes changed in the appropriate direction; (4) final beliefs were more congruent with the target alternative belief after subjects read explanatory information than after they read statistical information. Evidence was mixed regarding whether explanatory evidence was less subject to evaluation bias and subsequent attitude polarization than statistical information. In addition, explanation availability mediated the effectiveness of information in determining final beliefs, and evaluations of the evidence mediated the effect of initial beliefs on attitude polarization. A motivational construct, attitudes toward gay men, was related to initial beliefs and belief change--those with negative attitudes had more inappropriate beliefs and displayed less change in beliefs than those with moderate attitudes. However, evaluations of evidence were better predicted by initial beliefs than by attitudes toward gay men. This study has clear implications for those attempting to change beliefs, including those responsible for AIDS education: explanatory evidence is more effective than statistical evidence in changing beliefs.