A well known example of voter conformism is a bandwagon effect. A bandwagon effect occurs when the poll prompts voters to back the candidate shown to be winning in the poll, thus increasing his/her chances of being on the ‘winner’s side’ in the end. The idea that voters are susceptible to such an effect is old, and has remained persistent in spite of much debate on its empirical existence. Bartels, for instance, shows that voters are motivated in part by a desire to vote for the winning candidate. The opposite of the bandwagon effect is an underdog effect; this occurs when people vote, out of sympathy, for the candidate perceived to be ‘losing’ the elections. In a meta-study of research on this topic, Irwin and van Holsteyn show that from the 1980s onward a bandwagon effect is found more often by empirical researchers, while it finds less empirical evidence for the existence of an underdog effect than that for the existence of a bandwagon effect.
There have been at least two explanations for the existence of voter conformism.
The first consists in assuming that polls may exert a normative influence over voters; when voters perceive the existence of a social norm – defined by a majority preference expressed in polls in the case of a bandwagon effect – they may feel compelled to abandon their views and comply with such norms, to avoid perhaps cognitive dissonance.
The second, which seems more compelling, consists in assuming that individuals may be influenced by polls because they use revealed public preferences as information about the correct option to take.
Considering they have strong incentives to minimize the costs of acquiring the information necessary to make right choices, voters may rely upon ‘information shortcuts,’ such as group references, party identification, or knowledge about where other voters stand on issues.