Dm. Sanbonmatsu et al., THE SUBJECTIVE BELIEFS UNDERLYING PROBABILITY OVERESTIMATION, Journal of experimental social psychology, 33(3), 1997, pp. 276-295
Teigen (1974a, 1974b, 1983) observed that the numerical probabilities
assigned to a set of exhaustive and mutually exclusive events frequent
ly exceed one. Three experiments were performed to examine why these i
nflated numerical probability judgments form and what they reflect abo
ut people's subjective beliefs. Some work suggests that numerical prob
ability overestimations stem from a fundamental misunderstanding of th
e rules of probability calculation. Our findings, though, indicate tha
t biased hypothesis testing processes operate that contribute to the s
ubjective overestimation of the likelihood of a hypothetical event. Pe
ople tend to perceive events to be more plausible than is possible bec
ause of confirmatory processes characterizing the selective testing of
a hypothesis. Our findings indicate that these processes may lead to
the unwarranted disconfirmation of a focal hypothesis when the evidenc
e for all of the alternatives is weak. (C) 1997 Academic Press.