For a recent paper, researchers from Duke University, London Business School, and New York University conducted six studies across a variety of sports and other domains. In one study, the authors found that chess players had a lower chance of winning if their opponents had recently moved up in ranks. The more momentum an opponent had, the less likely a player was to win. In another study, the researchers analyzed nearly 60,000 professional tennis matches. they found that as an opponent gains momentum, a player’s chances of winning drop from 52 percent to 38 percent.

The likely reason this happens, the researchers determined, is not simply that opponents gaining momentum are always rapidly getting better at winning. Instead, the researchers found that players tended to expect opponents with momentum to keep rising. The players themselves, in other words, seemed to be anticipating their own failure. In a parallel scenario involving two competing watch brands, study participants expected a middling brand moving up in a fictitious ranking to eventually overshadow a luxury watch brand that was ranked higher and showed no sign of movement. It was almost as though mediocre things are given a boost if they’ve recently gone from “bad” to “just fine.”

Part of the reason momentum alone exerts such an influence seems to be that as we see the status of an opponent jumping up, we are struck by a fear of the opponent’s unpredictability.