People focus on optimistic scenarios and disregard pessimistic scenarios while predicting task completion times

J Exp Psychol Appl. 2000 Sep;6(3):171-82. doi: 10.1037//1076-898x.6.3.171.


Task completion plans normally resemble best-case scenarios and yield overly optimistic predictions of completion times. The authors induced participants to generate more pessimistic scenarios and examined completion predictions. Participants described a pessimistic scenario of task completion either alone or with an optimistic scenario. Pessimistic scenarios did not affect predictions or accuracy and were consistently rated less plausible than optimistic scenarios (Experiments 1-3). Experiment 4 independently manipulated scenario plausibility and optimism. Plausibility moderated the impact of optimistic, but not pessimistic, scenarios. Experiment 5 supported a motivational explanation of the tendency to disregard pessimistic scenarios regardless of their plausibility. People took pessimistic scenarios into account when predicting someone else's completion times. The authors conclude that pessimistic-scenario generation may not be an effective debiasing technique for personal predictions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Affect*
  • Attitude*
  • Female
  • Forecasting*
  • Humans
  • Male
  • Surveys and Questionnaires