Two university varsity swimming teams took the Attributional Style Questionnaire (ASQ) at the start of the season. Swimmers with a pessimistic explanatory style went on to show more unexpected poor performances during competition than optimistic swimmers. We then tested the purported mechanism of this effect by experimentally simulating defeat, giving each swimmer falsely negative times. Performance deteriorated for those swimmers with a pessimistic explanatory style for bad events on their next swim, whereas performance for those swimmers with an optimistic style did not.
Seligman, M. E., Nolen-Hoeksema, S., Thornton, N., & Thornton, K. M. (1990). Explanatory style as a mechanism of disappointing athletic performance. Psychological Science, 1(2), 143-146.