The bandwagon effect, also known as social proof or "cromo effect" and closely related to opportunism, is the observation that people often do and believe things because many other people do and believe the same things. The effect is often pejoratively called herding instinct, particularly when applied to adolescents. People tend to follow the crowd without examining the merits of a particular thing. The bandwagon effect is the reason for the bandwagon fallacy's success.
The bandwagon effect is well-documented in behavioral psychology and has many applications. The general rule is that conduct or beliefs spread among people, as fads clearly do, with "the probability of any individual adopting it increasing with the proportion who have already done so." As more people come to believe in something, others also hop on the bandwagon regardless of the underlying evidence.
Literally, a bandwagon is a wagon which carries the band in a parade, circus or other entertainment. The phrase "jump on the bandwagon" was first used in American politics in 1848 because of Dan Rice, President Lincoln's court jester. Dan Rice, a professional circus clown, used his bandwagon for Zachary Taylor's campaign appearances, to gain attention by using the music. As Taylor's campaign became more successful, more politicians strove for a seat on the bandwagon, hoping to be associated with the success. Later, during the time of William Jennings Bryan's 1900 presidential campaign, bandwagons had become standard in campaigns, and 'jump on the bandwagon' was used as a derogatory term, implying that people were associating themselves with the success without considering what they associated themselves with.
The bandwagon effect occurs in voting: some people vote for those candidates or parties who are likely to succeed (or are proclaimed as such by the media), hoping to be on the 'winner's side' in the end. The bandwagon effect has been applied to situations involving majority opinion, such as political outcomes, where people alter their opinions to the majority view. Such a shift in opinion can occur because individuals draw inferences from the decisions of others, as in an informational cascade.
Because of time zones, election results are broadcast in the eastern parts of the United States while polls are still open in the west. This difference has led to research on how the behavior of voters in western United States are influenced by news about the decisions of voters in other time zones. In 1980, NBC News declared Ronald Reagan to be the winner of the presidential race on the basis of the exit polls several hours before the voting booths closed in the west.
It is also said to be important in the American Presidential Primary elections. States all vote at different times, spread over some months, rather than all on one day, some states (Iowa, New Hampshire) have special precedence to go early while others have to wait until a certain date. This is often said to give undue influence to these states, a win in these early states is said to give a Candidate the "Big Mo" and has propelled many candidates to win the nomination. Because of this other states often try frontloading (going as early as possible) to make their say as influential as they can. In the 2008 presidential primaries many states had all or some of their delegates banned from the convention by the central party organisations for going too early. 5 states may lose half of GOP delegates Florida Democrats Stripped of Convention Delegates Due to Early Primary
Several studies have tested this theory of the bandwagon effect in political decisionmaking. In the 1994 study of Robert K. Goidel and Todd G. Shields in The Journal of Politics, 180 students at the University of Kentucky were randomly assigned to nine groups and were asked questions about the same set of election scenarios. About 70% of subjects received information about the expected winner. Independents, which are those who do not vote based on the endorsement of any party and are ultimately neutral, were influenced strongly in favor of the person expected to win. Expectations played a significant role throughout the study. It was found that independents are twice as likely to vote for the Republican candidate when the Republican is expected to win. From the results, it was also found that when the Democrat was expected to win, independent Republicans and weak Republicans were more likely to vote for the Democratic candidate.
A study by Albert Mehrabian, reported in The Journal of Applied Social Psychology, tested the relative importance of the bandwagon (rally around the winner) effect versus the underdog (empathic support for those trailing) effect. Bogus poll results presented to voters prior to the 1996 Republican primary clearly showed the bandwagon effect to predominate on balance. Indeed, approximately 6% of the variance in the vote was explained in terms of the bogus polls, showing that poll results (whether accurate or inaccurate) can significantly influence election results in closely-contested elections. In particular, assuming that one candidate "is an initial favorite by a slim margin, reports of polls showing that candidate as the leader in the race will increase his or her favorable margin". Thus, as poll results are repeatedly reported, the bandwagon effect will tend to snowball and become a powerful aid to leading candidates.
During the 1992 U.S. presidential election, Vicki G. Morwitz and Carol Pluzinski conducted a study, which was published in The Journal of Consumer Research. At a large northeastern university, some of 214 volunteer business students were given the results of student and national polls indicating that Bill Clinton was in the lead. Others were not exposed to the results of the polls. Several students who had intended to vote for Bush changed their minds after seeing the poll results.
Internationally, British polls have shown an increase to public exposure. Sixty-eight percent of voters had heard of the general election campaign results of the opinion poll in 1979. In 1987, this number of voters aware of the results increased to 74%. According to British studies, there is a consistent pattern of apparent bandwagon effects for the leading party.