Editing Vested interest (communication theory) (section)

===Drinking age experiment===
Various studies have been conducted to determine the effects of vested interest on attitude strengths. In one such study, Crano and Sivacek<ref name="S&C"/> visited a university in Michigan and gathered the results of a proposed drinking-age referendum. The referendum sought to increase the legal drinking age from 18 to 21. The respondents were divided into three categories: 1. high vested interest (those who would be significantly and immediately affected as a result of the referendum), 2. low vested interest (those who would be unaffected by the law change at the time of its inception), and 3. moderate vested interest (those who fell between the first two extremes). Although 80% of the subjects were opposed to the referendum, their respective levels of vested interest clearly indicated that the strength of their attitudes significantly affected their resultant behaviors. Half of the highly vested interest groups joined the anti-referendum campaign, but only a quarter of the moderately vested interest group and an eighth of the low vested interest group joined the campaign.<ref name="S&C"/> These results support Crano's theory of vested interest and reinforce the implications and considerations of stake, salience, certainty, immediacy, and self-efficacy discussed above. It also proves the correlation between vested interest and action, based on what level of involvement the three types of students were willing to participate in.