How Numeracy Influences Risk Comprehension and Medical Decision Making

Department of Human Development, Cornell University, B44 Martha Van Rensselaer Hall, Ithaca, NY 14853, USA.
Psychological Bulletin (Impact Factor: 14.76). 11/2009; 135(6):943-73. DOI: 10.1037/a0017327
Source: PubMed


We review the growing literature on health numeracy, the ability to understand and use numerical information, and its relation to cognition, health behaviors, and medical outcomes. Despite the surfeit of health information from commercial and noncommercial sources, national and international surveys show that many people lack basic numerical skills that are essential to maintain their health and make informed medical decisions. Low numeracy distorts perceptions of risks and benefits of screening, reduces medication compliance, impedes access to treatments, impairs risk communication (limiting prevention efforts among the most vulnerable), and, based on the scant research conducted on outcomes, appears to adversely affect medical outcomes. Low numeracy is also associated with greater susceptibility to extraneous factors (i.e., factors that do not change the objective numerical information). That is, low numeracy increases susceptibility to effects of mood or how information is presented (e.g., as frequencies vs. percentages) and to biases in judgment and decision making (e.g., framing and ratio bias effects). Much of this research is not grounded in empirically supported theories of numeracy or mathematical cognition, which are crucial for designing evidence-based policies and interventions that are effective in reducing risk and improving medical decision making. To address this gap, we outline four theoretical approaches (psychophysical, computational, standard dual-process, and fuzzy trace theory), review their implications for numeracy, and point to avenues for future research.

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    • "Moreover, healthcare professionals must take particular care in consultations with patients who have low health numeracy, to ensure that information is understood correctly (Weiss et al. 2005; Rothman et al. 2006; Fagerlin et al. 2007). Low numeracy affects people of all educational levels (Lipkus et al. 2001; Golbeck et al. 2005; Gazmararian et al. 2005; Peters et al. 2007; Reyna et al. 2009), including healthcare professionals. Nurses and pharmacists are known to struggle with drug dose calculations, posing a threat to patient safety in relation to the preparation and administration of drugs, intravenous (IV) fluids and nutritional supplements (Latif and Grillo 2002; Oldridge et al. 2004; McMullan et al. 2010; Wright 2010; Hegener et al. 2013). "

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    • "However, the accuracy of lay perceptions commonly decreases when it comes to estimating more complex numbers of risk, and systematic deviations between risk assessment and lay risk perception occur (see for further discussion Gigerenzer et al., 2008; Renner and Schupp, 2011). How well risk statistics are understood depends on numeracy, i.e., the ability to process basic numerical and probability concepts (Reyna et al., 2009). As expected, highly numerate adults are more likely to extract and use appropriate numerical principles and thereby have more complete and complex information than less numerate individuals. "
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    ABSTRACT: Perceptions of health-related risks are a prerequisite for taking protective action, adopting a healthier lifestyle, attending health screenings, and adhering to medical care. It seems inherently plausible that the greater the perceived risk for one's own health is the greater the motivation for protective action. Accordingly, it is important to understand how people perceive health risks, how accurate these perceptions are, and how information about one's own health risk is received. This article focuses on general and personal risk perceptions, discusses the role of intuition in personal risk perception, and presents findings regarding reactions to individualized feedback about risk.
    No preview · Chapter · Dec 2015
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    • "The findings replicate past work showing that those high in numeracy have less distorted value functions (Schley & Peters, 2014), and provide evidence that they also have less distorted probability functions, consistent with past findings of greater sensitivity to changes in probabilities (see Reyna et al., 2009). While curvature of the probability function was moderately correlated with numeracy in the present study, elevation was only weakly correlated, suggesting different sources of variation. "
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    ABSTRACT: It is well documented that individuals distort outcome values and probabilities when making choices from descriptions, and there is evidence of systematic individual differences in distortion. In the present study, we investigated the relationship between individual differences in such distortions and two measures of numerical competence, numeracy and approximate number system (ANS) acuity. Participants indicated certainty equivalents for a series of simple monetary gambles, and data were used to estimate individual-level value and probability distortion, using a cumulative prospect theory framework. We found moderately strong negative correlations between numeracy and value and probability distortion, but only weak and non- statistically reliable correlations between ANS acuity and distortions. We conclude that low numeracy contributes to number distortion in decision making, but that approximate number system acuity might not underlie this relationship.
    Full-text · Article · Dec 2015 · Psychonomic Bulletin & Review
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