According to Wikipedia:
The bandwagon effect is a phenomenon whereby the rate of uptake of beliefs, ideas, fads and trends increases the more that they have already been adopted by others. In other words, the bandwagon effect is characterized by the probability of individual adoption increasing with respect to 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.
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.
So I'd like to know if there are countries in which polls are forbidden completely or forbidden for a few months before elections take place. (Of course not opinion polls in general, but surveys on the upcoming election)