For the study, Greenberg and colleagues first recruited basketball players to play two back-to-back, one-on-one games with lead researcher Colin Zestcott, another psychologist at the University of Arizona. (The players didn’t know that Zestcott was a researcher; they thought he was another study participant.) After the first game, half of the participants were randomly assigned to take a questionnaire on how they felt about basketball. The other half took one about their thoughts on their own death.

Those that took the spooky survey saw a 40-percent boost in their individual performance during the second game as compared with their first. Those that took the non-macabre survey saw no change

In a second experiment, participants were given a basket-shooting challenge, which a researcher described to them in a 30-second tutorial. Based on a coin-toss, half the participants got the tutorial while the researcher was wearing a plain jacket. The other half saw the researcher in a T-shirt with a skull-shaped word-cloud made entirely of the word ‘death.’ The participants’ performance on the shooting challenge was then scored by another researcher who didn’t know which players saw the death shirt.

In the end, players who did see the shirt took more shots, and outperformed by 30 percent, those that just saw the jacket.

Source: “You’re all going to die”: A scientifically proven pep-talk for winning