Ir. Newby-clark et al., People focus on optimistic scenarios and disregard pessimistic scenarios while predicting task completion times, J EXP PSY-A, 6(3), 2000, pp. 171-182
Task completion plans normally resemble best-case scenarios and yield overl
y optimistic predictions of completion times. The authors induced participa
nts to generate more pessimistic scenarios and examined completion predicti
ons. Participants described a pessimistic scenario of task completion eithe
r alone or with an optimistic scenario. Pessimistic scenarios did not affec
t predictions or accuracy and were consistently rated less plausible than o
ptimistic scenarios (Experiments 1-3). Experiment 4 independently manipulat
ed scenario plausibility and optimism. Plausibility moderated the impact of
optimistic, but not pessimistic, scenarios. Experiment 5 supported a motiv
ational explanation of the tendency to disregard pessimistic scenarios rega
rdless of their plausibility. People took pessimistic scenarios into accoun
t when predicting someone else's completion times. The authors conclude tha
t pessimistic-scenario generation may not be an effective debiasing techniq
ue for personal predictions.