A new survey shows that social media such as Twitter and Facebook are likely to play a key role in the outcome of Wednesday's elections. According to a poll by Nielsen Korea of 1,000 citizens aged 18 to 54, 85 percent of respondents said information on social networking services would have an impact on their selection.

However, just 14 percent of respondents saw social media sites as a very credible source of information, while 63 percent described them as reasonably trustworthy. Some 22 percent dismissed them as not at all credible. Overall, nearly 40 percent of respondents in the poll said social media influenced their political involvement.