The rival auction houses approached the impending game very differently. Kanae Ishibashi, the then president of Christie’s in Japan, took the challenge seriously. She studied the psychology of the game and phoned a friend: She consulted 11-year-olds Alice and Flora Maclean, the twin daughters of Nicholas Maclean, the international director of Christie’s Impressionist and modern art department at the time, figuring they’d have more expertise on the playground ritual than she. The twins suggested Ishibashi start with scissors—as Flora explained to the New York Times: “Rock is way too obvious, and scissors beats paper.” In preparation for the competition, the auction house executive also prayed, carried charm beads, and sprinkled salt for good luck.

Sotheby’s, on the other hand, believed the game would come down to chance, “so we didn’t really give it that much thought,” Blake Koh, a former specialist in the house’s Los Angeles office, said at the time (he now works at Phillips). “We had no strategy in mind.” (Both Christie’s and Sotheby’s declined to comment for this story.)

On game day, Ishibashi met her Sotheby’s competitor in a board room. Instead of playing rock, paper, scissors the traditional way—thumping a fist on an outstretched palm, then making the gesture that corresponds to the object thrown—the participants wrote their object of choice on a piece of paper. Ishibashi dutifully chose scissors, beating her paper-throwing opponent in one swift go—scissors cut paper.