80 undergraduates were exposed to arguments advocating supplemental vitamin use. Ending arguments with rhetorical questions (when compared with statements) resulted in more favorable attitudes towards vitamin use and a more favorable profile of questions generated about the message topic. The question profile, principally reflecting uncertainty concerning personal nutrition, mediated the attitudinal effect.
Source: “Question effects on question generation and the mediation of attitude change.” from Psychol Rep. 1994 Aug;75(1 Pt 1):209-10.
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