Dynamic public opinion: Communication effects over time

We develop an approach to studying public opinion that accounts for how people process competing messages received over the course of a political campaign or policy debate. Instead of focusing on the fixed impact of a message, we emphasize that a message can have variable effects depending on when it is received within a competitive context and how it is evaluated. We test hypotheses about the effect of information processing using data from two experiments that measure changes in public opinion in response to alternative sequences of information. As in past research, we find that competing messages received at the same time neutralize one another. However, when competing messages are separated by days or weeks, most individuals give disproportionate weight to the most recent communication because previous effects decay over time. There are exceptions, though, as people who engage in deliberate processing of information display attitude stability and give disproportionate weight to previous messages. These results show that people typically form significantly different opinions when they receive competing messages over time than when they receive the same messages simultaneously. We conclude by discussing the implications of our findings for understanding the power of communications in contemporary politics.