Abstract
People often overestimate probabilities of conjunctive events. The authors explored whether the accuracy of conjunctive probability estimates can be improved by increased experience with relevant constituent events and by using memory aids. The first experiment showed that increased experience with constituent events increased the correlation between the estimated and the objective conjunctive probabilities, but that it did not reduce overestimation of conjunctive probabilities. The second experiment showed that reducing cognitive load with memory aids for the constituent probabilities led to improved estimates of the conjunctive probabilities and to decreased overestimation of conjunctive probabilities. To explain the cognitive process underlying people’s probability estimates, the configural weighted average model was tested against the normative multiplicative model. The configural weighted average model generates conjunctive probabilities that systematically overestimate objective probabilities although the generated probabilities still correlate strongly with the objective probabilities. For the majority of participants this model was better than the multiplicative model in predicting the probability estimates. However, when memory aids were provided, the predictive accuracy of the multiplicative model increased. In sum, memory tools can improve people’s conjunctive probability estimates.
Highlights
EXPLORING THE OVERESTIMATION OF CONJUNCTIVE PROBABILITIES Over the last decades, hundreds of studies have explored people’s ability to estimate conjunctive probabilities (Wedell and Moro, 2008)
The accuracy of the constituent probability estimates increased with growing experience in terms of r and root mean squared error (RMSE) but not in terms of mean error (ME), which was already low in Block 1
One-tailed independent samples t tests showed that the increase in accuracy was significant both when considering RMSE, t (54) = 2.69, p = 0.005, and when considering r, t (54) = 1.88, p = 0.033
Summary
EXPLORING THE OVERESTIMATION OF CONJUNCTIVE PROBABILITIES Over the last decades, hundreds of studies have explored people’s ability to estimate conjunctive probabilities (Wedell and Moro, 2008). A problematic aspect of previous literature on the accuracy of conjunctive probability estimates is that almost all attention has been devoted to the coherence criterion We fear that this disproportionate focus might have led to an overly negative view of people’s ability to estimate conjunctive probabilities. To assess the probability of conjunctively sampling a black marble out of Box A and a black marble out of Box B, probability theory prescribes multiplying the two constituent probabilities:. This multiplicative rule holds whenever the two constituents are independent, as in the experiments presented below. The difference between RMSE and ME is that RMSE captures magnitude of deviation, whereas ME captures systematic bias
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
