Leading up to elections, voters often rely on the media as a source of information for each candidate running for office. Since the average voter does not know each candidate personally, they will turn to newspapers, TV, radio or the Internet to get information on where the candidates stand on particular issues in order to make an informed decision. Media exposure can therefore play a direct role in how a person ultimately casts their vote.
One of the most obvious ways the use of media influences voting behaviour is through the use of advertisements by political campaigns. A typical political ad will tout a candidate's experience or highlight where they stand on certain issues. In many cases, those same ads will be used to cast their opponent in a negative light. The ad might, for example, draw attention to them taking an unpopular stance on a certain social or political issue. Such political ads are designed to draw voters into supporting one candidate over another by appealing to their desire to vote for someone who aligns closely with their own political philosophy.
By their nature, opinion polls influence what choices voters make going into an election. An opinion poll can create what is called a bandwagon effect. In this situation, a poll can prompt some voters to back a candidate who is shown to have a significant lead in the poll because they believe that candidate will win the election. These voters act out of a desire to align themselves with the popular candidate. Opinion polls can also work to influence public perception of a candidate. If a poll is taken after a candidate makes a major speech or debate, poll numbers will frame the context in which voters view that speech or debate. If they are trailing, the candidate is viewed as struggling in the campaign. If they lead, they are seen as the front-runner.
Media coverage of elections can go a long way toward determining which issues end up becoming most important or relevant during any given election. If several newspaper articles and TV reports choose to emphasise economic issues, for example, a candidate running for political office may tailor their message to tell voters how they will deal with economic problems once elected or re-elected. Media influence can dictate what talking points emerge during the course of an election simply by pointing out a candidate's previous record and experience in dealing with whatever hot button issues are before the public.
Unbiased reporting is a foundational element of journalistic ethics. The reality is that mass media political bias has existed almost since the invention of the printing press and has influenced plenty of elections since that time. The rise of 24-hour news channels on cable TV during the 1990s fuelled public perception that media bias plays a major role in shaping the political environment. A common criticism on these channels is many of the reporters and talk-show hosts report in a manner slanted to put the political ideology of their corporate owners in a positive light. This can include favourable reports on candidates or parties who match that ideology and attacking candidates or parties who are opposed to it.