For this study, twelve persuasive messages were designed. Messages were written across two topics (recycling and compact fluourescent bulb), and were manipulated to contain emotion (hope, guilt or no emotion), personal agency arguments (present or not) or a combination of emotion (hope or guilt) and personal agency. All messages were designed to be consistently strong (i.e., contain a high-quality, persuasive argument), and to be consistent regarding other factors, such as message length, in order to isolate the effects of the manipulations.
This study was conducted with 225 participants, located through convenience sampling as students in social science classes at a large, Midwestern university. Students were asked demographic and pre-attitudinal questions, then read one of 12 persuasive messages designed toward pro-environmental behavioral intentions. Participants then completed an online questionnaire asking them about emotions they felt after reading the essay, attitudes and behavioral intentions toward the topic and questions of perceived message effectiveness.
Overall, the manipulations were shown to be effective and, for those who received messages on the topic of recycling, the manipulations were shown to increase (1) general perceived ratings of message effectives, (2) attitude towards the topic, and (3) promote behavioral intention toward pro-environmental behavior. Further, for those in the recycling group, those with the highest pre-message attitude toward the behavior were found to have the highest post-message means regarding perceived message effectiveness, attitude toward the behavior and behavioral intention.
Finally, for those who read messages on the topic of recycling, the effects of the manipulations were found to be significant in regard to behavioral intention above and beyond the contribution of the constructs of the Theory of Planned Behavior (i.e., attitude toward the behavior, subjective norm and perceived behavioral control). These findings were inconsistent with the results of the analyses in regard to the CFL group. It can be theorized that the differences between the two groups was reflective of the fact that those in the recycling group had much higher levels of pre-message knowledge, attitude and personal relevance regarding the topic.