Date Awarded


Document Type


Degree Name

Master of Arts (M.A.)




Christopher Ball

Committee Member

Joanna Schug

Committee Member

Harvey Langholtz


Bayesian probability problems are notoriously difficult for people to solve accurately. Base rate neglect refers to the hypothesis that people ignore base rate information in preference for individuating information when making these probability judgments (Kahneman & Tversky, 1973). Correct answers to base rate neglect problems often require complex Bayesian calculations involving probability information embedded within realistic event descriptions. The past research emphasis on base rate neglect responses for such problems has overlooked the fact that responses can actually vary widely across participants and within participants from one problem to the next. The verbal protocol analyses of participants’ decision making processes found in the current study revealed that participants use a variety of cognitive strategies to solve such problems. The between-participant and within-participant variability can result from simple miscalculations to difficulties with translating probability statements into numerical calculations. This translation process can be further complicated by idiosyncratic subjective interpretations of the event descriptions and a basic misunderstanding of objective probability information. The results of the current study highlight that improving an individual’s Bayesian reasoning requires the instructional procedure to be tailored to their sources of difficulties, and that individual protocol analyses could help define these instructional procedures.



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