In a tight election campaign there’s no telling what will separate the winners from the losers on voting day. A key policy announcement, an embarrassing gaffe or an impressive debate performance can end up making all the difference.

But according to a new U.S. study, there’s an untapped force that has the potential to be just as decisive as any of those: Internet search rankings.

Research published this month in the academic journal Proceedings of the National Academy of Sciences found that search engine results could have a powerful effect on how people vote. It determined that if search rankings were manipulated to allow a preferred candidate to dominate the top results, it could shift voting preferences of undecided voters by at least 20 per cent.

The paper did not accuse Google or any other company of manipulating results; nor is there evidence that search engines have deliberately interfered in elections anywhere. But the researchers said their results suggest that a search engine company, if it chose to, “has the power to influence the results of a substantial number of elections with impunity.”

The authors dubbed it the “search engine manipulation effect,” or SEME.

“This is a very scary phenomenon,” study co-author Dr. Robert Epstein told the Star.

Recent polls suggest the Canadian federal election could come down to the wire. According to a poll conducted by Forum Research on Aug. 10 and 11, the NDP had 34 per cent support, compared to the Conservatives’ 28 per cent, and the Liberals’ 27 per cent. One poll published earlier in the month found 60 per cent of voters were still undecided.

The paper looked at five double-blind, randomized controlled experiments using 4,556 undecided voters in the U.S. and India. Certain demographic groups, including moderate Republicans, were more susceptible to the effect than others, but most were unaware that search rankings were being manipulated.

The difficulty to detect such manipulation is one of the things that make SEME so potentially dangerous, said Epstein, a research psychologist. “When people are unaware of a source of influence, they’re helpless (to combat it).”

The paper suggested SEME’s influence could be amplified by search-engine monopoly in many areas. When it comes to media like newspapers or radio shows, voters have a wide range of options. But in many locales, a single company, Google, handles the vast majority of Internet searches. In addition, many modern elections are very close, meaning even a small shift in undecided voters’ behaviour could be decisive.

Epstein, who in previous writings has criticized Google’s reach in other areas of society, warned that unless steps are taken to reduce search engines’ potential influence, elections risk being manipulated and becoming “meaningless.”

A spokesperson for Google Canada declined the Star’s request for an interview but suggested in an emailed statement it would be against the company’s best interests to skew political search results.

“Providing relevant answers has been the cornerstone of Google’s approach to search from the very beginning,” wrote Leslie Church. “It would undermine people’s trust in our results and company if we were to change course.”

Several experts who spoke to the Star cautioned about drawing firm conclusions from the SEME paper because experimental studies, in which researchers create artificial scenarios and observe the results, tend to overstate how powerful a phenomena would be in a real-life environment.

“We shouldn’t panic about these results, but we should be aware of them,” said Conrad Winn, a political science professor at Carleton University and an expert in public affairs.

Winn said the study was “entirely valid” and it’s possible that search engines could sway an election, but in our media-saturated world, “the likelihood is very low.”

“There are countless sources of information,” he said.

Another safeguard is that while search engines can determine what information voters see, how voters will use that information to vote isn’t predictable.

People are often heavily influenced “by things of no great consequence,” Winn said, like a politicians’ physical appearance. “It tells you how immune voters are to information.”

The power of search engines: By the numbers

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50 per cent: Amount of search engine clicks that go to the first or second results on the page

86 per cent: Number of U.S. voters who use search engines to get information about candidates

75 per cent: Number of subjects in one experiment who couldn’t detect that search results were being manipulated

340,000: Number of additional people who voted in the 2010 U.S. congressional elections after Facebook sent get-out-the-vote messages to users

1.2 per cent: Margin of victory up to which researchers found election outcomes would be vulnerable to search engine manipulation

Source: The search engine manipulation effect (SEME) and its possible impact on the outcomes of elections, Robert Epstein and Ronald E. Robertson, Proceedings of the National Academy of Sciences

Anything that can have even a minor effect on election results could end up being decisive if the vote is close. Some are so tight they have to be decided by a flip of a coin — literally.

United Kingdom, 2010: Sinn Fein candidate Michelle Gildernew squeaked out a victory in the Northern Irish district of Fermanagh and South Tyrone with 21,304 votes, just four more than Rodney Connor, an Independent.

Prince Edward Island, 2015: The May provincial election in Vernon River-Stratford was decided by a coin toss after the Liberal and Conservative candidates each won exactly 1,173 votes.

Florida, 2000: George W. Bush won the state, and with it the U.S. presidency, by controversially besting Al Gore by only 537 votes.

Quebec, 2003: The provincial contest in the riding of Champlain had to be redone after the Parti Québécois’ Noëlla Champagne tied with Liberal Pierre Brouillette at 11,852 votes. Champagne took the second vote.

Nevada, 2002: When Republican Dolores Honeycutt and Democrat R.J. Gillum each wound up with 107 votes for a seat on the Esmerelda County Commission, they settled matters by — what else — drawing cards. Gillum’s jack of spades beat Honeycutt’s jack of diamonds