The Minnesota Vikings kick off their 2015 season tonight with a game against the San Francisco 49ers.
Both teams’ fans are likely to have an overly rosy view of how well their players are going to do tonight — and throughout the season.
For, as a study published last week in the journal PLOS ONE reports, National Football League (NFL) fans collectively believe their favorite teams are going to win more than 300 games this season — a statistical impossibility.
The reason for these unrealistic expectations is a psychological phenomenon known as optimism bias. It’s the tendency of people to overestimate the likelihood of experiencing a positive outcome and to underestimate the likelihood of experiencing a negative one.
Challenging to research
Optimism bias has been observed in many situations. Studies have found, for example, that people tend to be overly optimistic about their risk for getting in a traffic accident, or developing cancer or getting injured on the job.
Americans, especially young people, conservatives and members of the upper class, also tend to overestimate social mobility in the U.S. — the ability of people to move up economically by working hard and saving money.
Optimism bias is believed to help inspire humans to continue persevering, even under difficult circumstances. But it can also have negative consequences. People who underestimate health risks, for example, may not seek medical care when the need actually arises.
And people who overestimate their personal chances at social mobility may vote against their own economic interests.
Conclusively demonstrating that optimism bias exists is a challenge, however, primarily because most studies do not use a system with zero-sum outcomes. (The fact that one person avoids cancer doesn’t mean that another will develop the disease.) So it’s difficult to establish with certainty whether people’s optimism about outcomes that affect them are biased or not.
That’s why the authors of the current study turned to NFL fans. The NFL “is the perfect system to study optimism bias because it’s zero sum — one team winning means another team losing,” explains Brad Love, the study’s lead author and a psychologist at the University College London, in a released statement.
For the study, Love and his colleagues surveyed 1,116 NFL fans (mean age: 34) last April. They were asked to predict how many games they believed both their favorite team and least favorite teams would win this season.
The researchers averaged these predictions by individual teams and then across all teams. The number of wins predicted by the fans for their favorite team averaged 9.59, compared to 6.10 wins for the team that they most disliked. That meant the fans had collectively predicted a total of 307 victories for their favorite teams — 51 more than possible.
The study found that the New England Patriots were the most-liked team among the fans surveyed. It was also, however, the one most disliked. Both groups — those who liked and those who disliked the Patriots — were optimistic about the team doing well in 2015, but the fans were slightly more so, predicting, on average, one more victory.
This “optimism” gap between the predictions of fans and rivals was also narrow (about one game) for the Denver Broncos, the Seattle Seahawks and the Philadelphia Eagles. The gap was widest for the Cincinnati Bengals and the Arizona Cardinals, whose fans predicted an average of 6.6 more wins than did people who declared a dislike for these teams.
“It’s interesting that both fans and rivals of high-profile, successful teams are generally in agreement about their expected performance,” said Love. “By contrast, we see the largest optimism gap for lower-profile teams that receive little national media coverage, enabling fans and local media to construct their own optimistic narratives.”
Unfortunately, the study does not mention the Minnesota Vikings.
Experts also biased
Sports reporters — so-called experts — appear to have biases similar to those of NFL fans.
Love and his colleagues examined data from a pre-season 2014 survey of 32 of ESPN’s football reporters. The experts were asked to predict the final record for the team they had been assigned that year to cover. Collectively, they predicted an average of 8.93 wins for the 16-game season — significantly greater than the average number of wins possible.
“We should perhaps take the predictions of experts assigned to a single team with a pinch of salt as they may not appreciate the bigger picture,” said Love.
Implications beyond football
This study provides an interesting insight into a psychological phenomenon that affects all of us, whether we follow football or not.
“We find that optimism bias is not limited to one’s own prospects, but extends to those dear to an individual such as a favored team,” write Love and his colleagues in their paper. “These results align with the finding that people judge their friends to be better than average.”
“Perhaps these positive beliefs about close associates confer many of the proposed advantages of the optimism bias to others,” the researchers add. “Indeed, these positive evaluations of close associates may contribute to recipients developing the optimism bias. In effect, positivity may be contagious even in situations where there are only so many winners.”
You can read the study in full on the PLOS ONE website.