Whether people are making financial decisions in the stock market or worrying about terrorism, they are likely to be influenced by what others think. And, according to a new study in this month's Journal of Personality and Social Psychology, published by the American Psychological Association (APA), repeated exposure to one person's viewpoint can have almost as much influence as exposure to shared opinions from multiple people. This finding shows that hearing an opinion multiple times increases the recipient's sense of familiarity and in some cases gives a listener a false sense that an opinion is more widespread then it actually is.

In a series of six experiments that included 1044 students, from the University of Michigan, Princeton University, Rutgers University, University of Michigan -- Dearborn, University of Toledo and Harvard University, researchers sought to understand individuals' accuracy in identifying group norms and opinions. The experiments included dividing students into three groups, (three person control group, single opinion group and repeated opinions group).

Participants in the three person control group read three opinion statements each made by a different group member. The participants in the repeated opinion group read the same three statements but they were all attributed to one group member. Those in the single opinion control group read one opinion statement from one group member.

The studies found that an opinion is more likely to be assumed to be the majority opinion when multiple group members express their opinion. However, the study also showed that hearing one person express the same opinion multiple times had nearly the same effect on listener's perception of the opinion being popular as hearing multiple people state his/her opinion.

Researchers examined the underlying processes that take place when individuals estimate the shared attitude of a group of people and how that estimation of collective opinion can be influenced by repetition from a single source. Since gauging public opinion is such an essential component in guiding our social interactions, this research has implications in almost every facet of modern day life.

"This study conveys an important message about how people construct estimates of group opinion based on subjective experiences of familiarity," states lead author Kimberlee Weaver, (Ph.D), of Virginia Polytechnic Institute and State University. "The repetition effect observed in this research can help us to understand how our own impressions are influenced by what we perceive to be the reality of others. For example, a congressman may get multiple phone calls from a small number of constituents requesting a certain policy be implemented or changed, and from those requests must decide how voters in their state feel about the issue. This study sheds light on the cognitive processes that take place that may influence such a decision."

Article: Inferring the Popularity of an Opinion From Its Familiarity: A Repetitive Voice Can Sound Like a Chorus. Kimberlee Weaver, Virginia Polytechnic Institute and State University, Stephen M. Garcia and Norbert Schwarz, University of Michigan, and Dale T. Miller, Stanford University; Journal of Personality and Social Psychology: Vol. 92, No. 5