WASHINGTON (Reuters) - On the Saturday before the November 6 election, President Barack Obama might want to root for Ohio State University's football team when it takes on his home-state University of Illinois. A win by the Buckeyes could boost his chances of carrying Ohio, a crucial battleground state.
Obama can take heart that Florida beachgoers haven't suffered from a spate of shark attacks this year, which could have hurt his prospects there. On the other hand, the brutal drought that has gripped much of the Midwest could make it tougher for the president to win Iowa.
In 1980, Ronald Reagan famously asked Americans to base their votes on whether they were better off than they had been four years earlier - a mantra repeated this year by Obama's rival, Republican Mitt Romney.
But a growing body of research indicates that many Americans vote based on how they're feeling on that particular day - and that if they're happy, it can be good news for incumbents. Voters' feelings can hinge on factors beyond the control of any politician, from the weather to the play of local sports teams.
Voters typically know how the economy has performed over the past six months, but not the past four years, researchers say. Many aren't aware of major political developments, let alone candidates' policy views. The daily twists and turns of the campaign have little impact.
"You might imagine there's an ideal world in some peoples' heads where everyone votes on policy and knows what the candidates and parties stand for," said Gabriel Lenz, a political science professor at the University of California, Berkeley. "I think we're pretty sure we're not in that world."
Surveys have shown for decades that a significant number of voters know little about politics. This year appears to be no exception.
Nearly half of those surveyed by the Pew Research Center in July didn't know that Republican Mitt Romney favors more restrictions on abortion than Obama.
Only 40 percent knew that Republicans control the House of Representatives - a crucial piece of information needed to assess the Democratic president's tenure and the partisan gridlock that has plagued Washington.
Voters with strong partisan affiliations tend to know more about politics. But they also are more likely to retain inaccurate information if it reinforces their views.
For example, nearly one-third of Republicans polled by YouGov last January said they believed Obama was born abroad - and therefore ineligible to be president, as conspiracy theorists claim - even though Obama had released a long-form birth certificate showing that he was born in the United States.
Ignorance makes sense for some voters when it comes to politics, said George Mason University law professor Ilya Somin.
The act of voting is relatively easy, but it takes a lot more effort to gather the amount of information needed to determine which candidate reflects a voter's own policy views. Because any single vote is extremely unlikely to tip the outcome of an election, many voters believe it does not make sense for them to invest a lot of time in following a campaign, he said.
With limited time and interest, voters often rely on shortcuts to settle on a candidate, whether party affiliation or a sense that a candidate shares a voter's values.
A candidate's policy positions tend not to matter much - in fact, voters are more likely to shift their own policy views if they don't line up with their chosen candidate than they are to vote for someone else, Lenz said.
Many others appear to treat elections as a referendum on the performance of the incumbent.
Romney hopes voters will punish Obama for the nation's high unemployment rates and sluggish economic growth the president has presided over since taking office in January 2009.
But most voters have a hard time thinking back that far. So they tend to look at the six months to a year before the election as a proxy for the incumbent's term, according to research by Larry Bartels, a political science professor at Vanderbilt University.
When incumbents have presided over robust election-year growth, as in 1964 (Lyndon Johnson) and 1984 (Reagan), they have been re-elected handily. In years when growth has been less robust, the results typically have been closer.
This short-term focus has had real consequences.
Republican candidates Dwight Eisenhower in 1952, Richard Nixon in 1968 and George W. Bush all owed their victories to the fact that voters either forgot or ignored strong periods of income growth early in the terms of their Democratic predecessors, Bartels writes in "Unequal Democracy: The Political Economy of the New Gilded Age."
This time around, the pattern might help Obama, who has presided over periods in 2009 and 2011 when personal income actually shrank. Based on this year's mediocre-but-still-positive growth in personal income and gross domestic product, many forecasters expect Obama to defeat Romney next month - a scenario that current opinion polls reflect.
"The die is cast, I'd say," said George Washington University political scientist John Sides.
Voters seem to hold presidents accountable for events over which they had no control.
One group of researchers found that incumbent presidents, senators and governors got an average boost of 1.6 percentage points if the local college football team won shortly before election day.
The increased sense of well-being that a victory fostered among fans made them more likely to stick with an incumbent rather than vote for a challenger, the researchers found.
The effect was more dramatic in areas where the local team had a large following. That could have implications in states such as Ohio, Florida and Michigan, which are home to successful college football programs and are likely to play a key role in determining who wins the presidency.
"The football stuff, it's alarming," said Loyola Marymount University economics professor Andrew Healy, one of the study's authors. "It's good to know how voters actually think."
A 2004 study by Bartels and Christopher Achen of Princeton University found that voters punished incumbent President Woodrow Wilson for a spate of 1916 shark attacks in New Jersey.
In the election that year, Wilson's share of the vote in the beach towns that suffered a decline in tourism after the attacks dropped by 8 percentage points from his total in the 1912 election. His vote total in nearby inland towns that were not affected by the shark attacks showed no difference from 1912.
"Shark attacks are natural disasters in the purest sense of the term, and they have no governmental solution. Yet the voters punished (Wilson) anyway," Bartels and Achen wrote.
Bartels and Achen also found that voters punish incumbent politicians for bad weather. Examining rainfall data back to 1896, they found that extreme droughts or floods cost office holders an average of 1.5 percentage points.
Lousy weather, even more than confusing ballots in Florida, may have cost Democratic Vice President Al Gore the White House in the 2000 election, Bartels and Achen wrote. They said that severe drought and excessive rainfall probably cost Gore victories in seven states, from Arizona to New Hampshire.
Bartels and Achen said their research indicated that voters are less rational than experts had previously thought.
"Democracies take their electoral direction from human beings with fewer capacities for self-government than either writer imagined," they wrote.
News media could help voters by putting developments in the economy or politics in the context of a president's four years in office, said political scientists who have studied the issue.
Politicians could avoid pandering to voters' fears by, for example, pointing out that trade with China allows U.S. consumers to save money on a wide range of goods.
Voters could help fix the problem as well, said George Mason University economist Bryan Caplan.
"If you don't know what you're doing," he said, "don't vote."
Editing by David Lindsey and Lisa Shumaker