Opinion Repetition

Opinion Repetition

Hearing one person repeat the same opinion is surprisingly influential.


When one voice sounds like many. I'm Bob Hirshon and this is Science Update.

Hearing one person repeat the same opinion is almost as influential as hearing it from several different people—at least when it comes to judging the opinion's popularity. This according to a series of experiments by Virginia Tech marketing professor Kim Weaver and her colleagues.

She says the effect was strongest in people who had no prior knowledge of the group's preferences. Yet they weren't simply misremembering who said what.


Our studies suggested that opinion repetition, in those cases, increases the familiarity of the opinion. And that people use that feeling of familiarity to make inferences about how many group members support the opinion.

The findings suggest that decision-makers should rely on systematic surveys, rather than general impressions, to gauge a group's opinion. I'm Bob Hirshon, for AAAS, the science society.

Making Sense of the Research

We all make judgments about what other people think. Often, these judgments are influenced by just a few people. For example, if you live in New York City and you and your close friends love rap, you might assume it's more popular than country music (it isn't, at least not in America). On the other hand, if you and your friends dislike your history teacher, you might assume that most people in your class don't. That might not be true either.

The most reliable way to find out what a group of people thinks is to ask every individual in an objective, non-biased scientific survey, record all answers, and total up the results. If you can't ask everyone, the next best thing is to survey a random sample of the group. For example, if your school has 1000 students, a random sample might include 100 students selected—you guessed it—at random from the entire school. Examples of non-random samples would be all the varsity athletes, or the 100 students with the best grades, or even the first 100 people to volunteer for the survey. These groups might have different opinions than the school as a whole.

Obviously, you can't conduct a scientific survey every time you need to pick pizza toppings for a party. However, this study shows one of the pitfalls that can lead to false impressions about what a group wants or believes. We've already pointed out that it's easy to assume that a large group shares the same opinion as yourself or your close friends. (Remember, your friends are not a random sample—you picked them!) This research goes one step further, and shows how easily we can mistake a single person's opinion for group consensus.

The researchers did several experiments, each slightly different. However, generally, they started by presenting some kind of group decision that had to be made. Two of the scenarios were: 1) whether to create more park space in a neighborhood, and 2) whether to recruit a company's new CEO from another firm, or to promote someone who already worked there.

The volunteers for the experiment then read opinions supposedly written by people in the group (in these cases, the neighborhood or the company). Some volunteers read only one opinion. Others read three opinions, all supporting the same thing, but for slightly different reasons. For example, "We need a CEO from the outside to help us grow," versus "An outside CEO will definitely have experience running a business." Sometimes, the volunteers were told that all three statements came from the same person; other times, they were told that the statements came from three different people.

As expected, volunteers that heard an opinion three times were much more likely to judge it as popular than were volunteers who heard the opinion only once. However, hearing the opinions of three different people was only slightly more powerful than hearing one person say essentially the same thing three times. The researchers found that this was even true when the volunteers specifically remembered that all three opinions came from the same person. Further experiments suggested that hearing an opinion stated and restated makes the opinion more familiar to the listener, which makes it seem more popular—even though that's not necessarily true.

So what? Well, in many cases, it doesn't really matter if we misunderstand the popularity of an opinion. But sometimes, it matters a great deal—such as when we're asked to make a decision on behalf of a group. People who make those decisions, from presidents of the freshman class to presidents of the United States, often hear opinions from some very vocal people, who may or may not represent the majority's view. This study suggests that decision-makers may wrongly assume that the opinion they hear most frequently is the most popular, even if they keep hearing it from one person.

Weaver also notes that we often look to the majority to shape our own opinions, especially in areas we don't know much about. Like it or not, it's a natural human tendency to "go with the group" unless we feel strongly otherwise. And while following the group has its own dangers (think of Nazi Germany), this study suggests that we're not even all that good at knowing what the group really thinks. Stepping back and taking a serious, objective survey will be much more accurate than just going with your general impression.

Now try and answer these questions:

  1. What was the basic finding of this study?
  2. Why did repeated opinions from the same person seem more popular?
  3. Can you think of specific situations in which this problem might occur? How would it affect the group as a whole?
  4. What does it mean to take an “unbiased” survey? What might be some examples of biased survey questions?

You may want to check out the September 7, 2007 Science Update to hear further information about this Science Update and the other programs for that week. This podcast's topics include: counting underwater volcanoes, a new source of antibiotics, which trees are better at fighting global warming, the power of repeating yourself, and crows that use tools to get food.

For Educators

Fundamentals of Polling, from the University of Connecticut's Roper Center, contains information about public opinion polling. The tutorial provides definitions, examples, and explanations that introduce students to the field of public opinion research.

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