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

ABSTRACT 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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Available from: Nathan F Dieckmann, Sep 26, 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.
    Psychonomic Bulletin & Review 12/2015; in press. DOI:10.3758/s13423-015-0849-9 · 2.99 Impact Factor
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    • "Individuals need a certain level of numeracy to comprehend these messages. One might expect college students to have sufficient numeracy, which is essential for risk assessments and decision making (Reyna et al., 2009), but this is not the case for all American college students. Based on a recent study on math achievement, American college students performed poorly in solving math problems, such as comparing the magnitude of two fractions (Richland, Stigler, & Holyoak, 2012). "
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    ABSTRACT: We conducted an experiment to examine whether risk perceptions of alcohol-attributable cancer influence college students' binge-drinking intention and to explore how message formats (text, table, and graph) and numeracy influence risk perceptions of alcohol-attributable cancer. We found that a majority of participants (87%) perceive some risks of alcohol-attributable cancer. Risk messages in tabular and graphic formats are more effective in elevating risk perceptions, but there is no significant difference between these two formats. Numeracy and its interaction with message formats, however, do not predict risk perceptions. We recommend risk messages should be delivered using tabular or graphic formats to enhance risk perceptions. We also advocate the less-is-more principle in presenting risk information.
    Journal of Drug Education 09/2015; 45(1):37-55. DOI:10.1177/0047237915604062 · 0.28 Impact Factor
    • "In line with previous research (Reyna et al., 2009), participants lower in numeracy overestimated the vaccination risk more so than those with greater numerical skills. However, this effect was limited to the 85% condition, that is, when almost all narratives implied vaccination risks. "
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    ABSTRACT: Immunization rates are below the Global Immunization Vision and Strategy established by the World Health Organization. One reason for this are anti-vaccination activists, who use the Internet to disseminate their agenda, frequently by publishing narrative reports about alleged vaccine adverse events. In health communication, the use of narrative information has been shown to be effectively persuasive. Furthermore, persuasion research indicates that the credibility of an information source may serve as a cue to discount or augment the communicated message. Thus, the present study investigated the effect of source credibility on the biasing effect of narrative information regarding the perception of vaccination risks. 265 participants were provided with statistical information (20%) regarding the occurrence of vaccine adverse events after vaccination against a fictitious disease. This was followed by 20 personalized narratives from an online forum on vaccination experiences. The authors varied the relative frequency of narratives reporting vaccine adverse events (35% vs. 85%), narrative source credibility (anti-vaccination website vs. neutral health forum), and the credibility of the statistical information (reliable data vs. unreliable data vs. control) in a between-subjects design. Results showed a stable narrative bias on risk perception that was not affected by credibility cues. However, narratives from an anti-vaccination website generally led to lower perceptions of vaccination risks.
    Journal of Health Communication 06/2015; DOI:10.1080/10810730.2015.1018605 · 1.61 Impact Factor
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