Separating psychological momentum from strategic momentum: Evidence from men's professional tennis

In dynamic contests, strategic momentum and psychological momentum potentially coexist, which makes it difficult to distinguish between the two. We employ the setting of professional tennis, which allows us to separate psychological from strategic momentum. In tennis, converting a break point potentially triggers both strategic momentum-due to a change in the relative position of the players-and psychological momentum-due to a change in the perception of the players. To distinguish between these two momentum types, we employ exogenously given interruptions. Interruptions are predicted to affect psychological momentum negatively, while leaving strategic momentum unaffected. Using 4930 game-by-game observations from 141 Grand Slam men's single matches, we show that the breaking players' probability of winning a game increases after converting a break point, which provides evidence for momentum. Moreover, we show that this momentum effect is negatively affected by an interruption. Thus, psychological momentum seems to be the main trigger leading to a performance increase after a converted break point.