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No abstract is provided for this article.
Decision makers are often presented with explicit likelihood assessments (e.g., there is a 10% chance that an attack will occur over the next 3 months) and supporting narrative evidence in forecasting and risk communication domains. Decision makers are thought to rely on both numerical and narrative information to the extent that they perceive the information to be diagnostic, accurate, and trustworthy. In two studies, we explored how lay decision makers varying in numeracy evaluated and used likelihood assessments and narrative evidence in forecasts. Overall, the less numerate reported higher risk and likelihood perceptions. In simple probabilistic forecasts without narrative evidence, decision makers at all levels of numeracy were able to use the stated likelihood information, although risk perceptions of the less numerate were more affected by likelihood format. When a forecast includes narrative evidence, decision makers were better able to use stated likelihood in a percentage as compared to frequency or verbal formats. The more numerate used stated likelihood more in their evaluations whereas the less numerate focused more on the narrative evidence. These results have important implications for risk analysts and forecasters who need to report the results of their analyses to decision makers. Decision makers varying in numerical ability may evaluate forecasts in different ways depending on the types of information they find easiest to evaluate.
Prior studies have observed that, in separate evaluation, the attractiveness of playing a simple gamble (7/36 to win $9; otherwise win nothing) is greatly enhanced by introducing a small loss (7/36 win $9; otherwise lose 5¢). The present studies tested and confirmed an explanation of this finding based on the concept of evaluability and the affect heuristic. Evaluators of the no-loss gamble lack a precise for how good $9 is, hence give it little weight in their judgment. The unattractive probability (7/36) determines the response. In the second gamble, comparison with the small loss makes $9 come alive with feeling and become weighted in the judgment, increasing attractiveness of the gamble. These results demonstrate the importance of contextual factors in determining affect and preference for simple risktaking opportunities. They show that the meaning, utility, and weighting of even a very familiar monetary outcome such as $9 is not fixed, but depends greatly on these contextual factors
