| Summary: | When people judge
risk or the probability of a risky prospect, single case narratives can bias
judgments when a statistical base-rate is also provided. In this work we
investigate various methodological and procedural factors that may influence
this narrative bias. We found that narratives had the strongest effect on a
non-numerical risk measure, which was also the best predictor of behavioral
intentions. In contrast, two scales for subjective probability reflected
primarily statistical variations. We observed a negativity bias on the risk
measure, such that the narratives increased rather than decreased risk
perceptions, whereas the effect on probability judgments was symmetric.
Additionally, we found no evidence that the narrative bias is solely produced
by adherence to conversational norms. Finally, changing the absolute number of
narratives reporting the focal event, while keeping their relative frequency
constant, had no effect. Thus, individuals extract a representation of
likelihood from a sample of single-case narratives, which drives the bias.
These results show that the narrative bias is in part dependent on the measure
used to assess it and underline the conceptual distinction between subjective
probability and perceived risk.
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