Rocio Garcia-Retamero

Using Icon Arrays to Communicate Medical Risks: Overcoming Low Numeracy

OBJECTIVE Icon arrays have been suggested as a potentially promising format for communicating risks to patients-especially those with low numeracy skills-but experimental studies are lacking. This study investigates whether icon arrays increase accuracy of understanding medical risks, and whether they affect perceived seriousness of risks and helpfulness of treatments. DESIGN Two experiments were conducted on samples of older adults (n = 59, 62 to 77 years of age) and university students (n = 112, 26 to 35 years of age). MAIN OUTCOME MEASURES Accuracy of understanding risk reduction; perceived seriousness of risks; perceived helpfulness of treatments. RESULTS Icon arrays increased accuracy of both low- and high-numeracy people, even when transparent numerical representations were used. Risks presented via icon arrays were perceived as less serious than those presented numerically. With larger icon arrays (1,000 instead of 100 icons) risks were perceived more serious, and risk reduction larger. CONCLUSIONS Icon arrays are a promising way of communicating medical risks to a wide range of patient groups, including older adults with lower numeracy skills.

Who proficts from visual aids: Overcoming challenges in people's understanding of risks

Many people have difficulties grasping numerical concepts that are prerequisites for understanding treatment risk reduction. Visual aids have been proposed as a promising method for enhancing comprehension. In a survey of probabilistic, nationally representative samples in two different countries (United States and Germany), we compared the effectiveness of adding different types of visual aids (icon arrays and bar graphs representing either affected individuals only or the entire population at risk) to the numerical information in either an absolute or a relative risk reduction format. We also analyzed whether peoples numeracy and graphical literacy skills affected the efficacy of the visual aids. Our results showed large improvements in accuracy both when icon arrays and when bar graphs were added to numerical information. Highest increases were achieved when the visual aids depicted the entire population at risk. Importantly, visual aids were most useful for the participants who had low numeracy but relatively high graphical literacy skills. Building on previous research showing that problems with understanding numerical information often do not reside in peoples minds, but in the representation of the problem, our results show that visual aids help to modify incorrect expectations about treatment risk reduction. Our results have important implications for medical practice.

Statistical Numeracy for Health: A Cross-cultural Comparison With Probabilistic National Samples

BACKGROUND Statistical numeracy is essential for understanding health-related risks and making informed medical decisions. However, this concept has not been investigated with probabilistic national samples or compared cross-culturally. We sought (1) to investigate differences in the level of statistical numeracy between 2 countries with different educational and medical systems-the United States and Germany; (2) to study the relationship between statistical numeracy and demographic characteristics such as age, sex, and education; and (3) to test whether a subjective measure of numeracy is a valid indicator of objective measures. METHODS In a survey of probabilistic, representative national samples in Germany and the United States, conducted in July and August 2008, we asked questions testing objective and subjective statistical numeracy. RESULTS German participants had higher numeracy skills than did US participants. On average, 68.5% (SE, 1.1%) and 64.5% (SE, 1.3%), respectively, of items testing objective numeracy were answered correctly. Subjective estimates of numeracy were a good indicator of the objective measures. There is a large gap in numeracy skills between persons with lower and higher educational levels, particularly in the United States. CONCLUSIONS Physicians should be aware that many patients may not understand all information relevant to making an informed decision. Fortunately, they can identify such patients and use nonnumerical presentation formats, such as graphical displays and analogies, to communicate important statistical information.

Graph literacy: a cross-cultural comparison

Background. Visual displays are often used to communicate important medical information to patients. However, even the simplest graphs are not understood by everyone. Objective. To develop and test a scale to measure health-related graph literacy and investigate the level of graph literacy in the United States and Germany. Design. Experimental and questionnaire studies. Setting. Computerized studies in the laboratory and on probabilistic national samples in the United States and Germany. Participants. Nationally representative samples of people 25 to 69 years of age in Germany (n = 495) and the United States (n = 492). Laboratory pretest on 60 younger and 60 older people. Measurements. Psychometric properties of the scale (i.e., reliability, validity, discriminability) and level of graph literacy in the two countries. Results. The new graph literacy scale predicted which patients can benefit from visual aids and had promising measurement properties. Participants in both countries completed approximately 9 of 13 items correctly (in Germany, x¯ = 9.4, s = 2.6; in the United States, x¯ = 9.3, s = 2.9). Approximately one third of the population in both countries had both low graph literacy and low numeracy skills. Limitations. The authors focused on basic graph literacy only. They used a computerized scale; comparability with paper-and-pencil versions should be checked. Conclusions. The new graph literacy scale seems to be a suitable tool for assessing whether patients understand common graphical formats and shows that not everyone profits from standard visual displays. Research is needed on communication formats that can overcome the barriers of both low numeracy and graph literacy.

Take-the-Best in Expert-Novice Decision Strategies for Residential Burglary

We examined the decision strategies and cue use of experts and novices in a consequential domain: crime. Three participant groups decided which of two residential properties was more likely to be burgled, on the basis of eight cues such as location of the property. The two expert groups were experienced burglars and police officers, and the novice group was composed of graduate students. We found that experts’ choices were best predicted by a lexicographic heuristic strategy called take-the-best that implies noncompensatory information processing, whereas novices’ choices were best predicted by a weighted additive linear strategy that implies compensatory processing. The two expert groups, however, differed in the cues they considered important in making their choices, and the police officers were actually more similar to novices in this regard. These findings extend the literature on judgment, decision making, and expertise, and have implications for criminal justice policy.

Do Icon Arrays Help Reduce Denominator Neglect

Background and Objective. Denominator neglect is the focus on the number of times a target event has happened (e.g., the number of treated and nontreated patients who die) without considering the overall number of opportunities for it to happen (e.g., the overall number of treated and nontreated patients). In 2 studies, we addressed the effect of denominator neglect in problems involving treatment risk reduction where samples of treated and non-treated patients and the relative risk reduction were of different sizes. We also tested whether using icon arrays helps people take these different sample sizes into account. We especially focused on older adults, who are often more disadvantaged when making decisions about their health. Design. Study 1 was conducted on a laboratory sample using a within-subjects design; study 2 was conducted on a nonstudent sample interviewed through the Web using a between-subjects design. Outcome Measures. Accuracy of understanding risk reduction. Results. Participants often paid too much attention to numerators and insufficient attention to denominators when numerical information about treatment risk reduction was provided. Adding icon arrays to the numerical information, however, drew participants’ attention to the denominators and helped them make more accurate assessments of treatment risk reduction. Icon arrays were equally helpful to younger and older adults. Conclusions. Building on previous research showing that problems with understanding numerical information often do not reside in the mind but in the representation of the problem, the results show that icon arrays are an effective method of eliminating denominator neglect.

Communicating Health Risks With Visual Aids

Informed decision making requires that people understand health risks. Unfortunately, many people are not risk literate and are biased by common risk communication practices. In this article, we review a collection of studies investigating the benefits of visual aids for communicating health risks to diverse vulnerable people (e.g., varying in abilities, ages, risk characteristics, and cultural backgrounds). These studies show that appropriately designed visual aids are often highly effective, transparent, and ethically desirable tools for improving decision making, changing attitudes, and reducing risky behavior. Theoretical mechanisms, open questions, and emerging applications are discussed.

How to Reduce the Effect of Framing on Messages About Health

ABSTRACTBACKGROUNDPatients must be informed about risks before any treatment can be implemented. Yet serious problems in communicating these risks occur because of framing effects.OBJECTIVETo investigate the effects of different information frames when communicating health risks to people with high and low numeracy and determine whether these effects can be countered or eliminated by using different types of visual displays (i.e., icon arrays, horizontal bars, vertical bars, or pies).DESIGNExperiment on probabilistic, nationally representative US (n = 492) and German (n = 495) samples, conducted in summer 2008.OUTCOME MEASURESParticipants’ risk perceptions of the medical risk expressed in positive (i.e., chances of surviving after surgery) and negative (i.e., chances of dying after surgery) terms.KEY RESULTSAlthough low‐numeracy people are more susceptible to framing than those with high numeracy, use of visual aids is an effective method to eliminate its effects. However, not all visual aids were equally effective: pie charts and vertical and horizontal bars almost completely removed the effect of framing. Icon arrays, however, led to a smaller decrease in the framing effect.CONCLUSIONSDifficulties with understanding numerical information often do not reside in the mind, but in the representation of the problem.

Visual representation of statistical information improves diagnostic inferences in doctors and their patients

Doctors and patients have difficulty inferring the predictive value of a medical test from information about the prevalence of a disease and the sensitivity and false-positive rate of the test. Previous research has established that communicating such information in a format the human mind is adapted to-namely natural frequencies-as compared to probabilities, boosts accuracy of diagnostic inferences. In a study, we investigated to what extent these inferences can be improved-beyond the effect of natural frequencies-by providing visual aids. Participants were 81 doctors and 81 patients who made diagnostic inferences about three medical tests on the basis of information about prevalence of a disease, and the sensitivity and false-positive rate of the tests. Half of the participants received the information in natural frequencies, while the other half received the information in probabilities. Half of the participants only received numerical information, while the other half additionally received a visual aid representing the numerical information. In addition, participants completed a numeracy scale. Our study showed three important findings: (1) doctors and patients made more accurate inferences when information was communicated in natural frequencies as compared to probabilities; (2) visual aids boosted accuracy even when the information was provided in natural frequencies; and (3) doctors were more accurate in their diagnostic inferences than patients, though differences in accuracy disappeared when differences in numerical skills were controlled for. Our findings have important implications for medical practice as they suggest suitable ways to communicate quantitative medical data.

Identity, Power, and Threat Perception A Cross-National Experimental Study

Realists in international relations and realistic conflict theorists in social psychology argue that the perception of threat in intergroup conflict is a function of power asymmetries between groups. In contrast, social constructivists and social identity theorists argue that a shared sense of identity can reduce perceptions of intergroup threat. In this article, we test these competing arguments using three laboratory experiments conducted in two different countries (Spain and the United States). Four findings emerge from the experiments: (1) a weak position in terms of military power increases threat perception, as realists predict; (2) shared identity decreases threat perception, as constructivists predict; (3) an interactive relationship between power and identity appears in two of the three studies; and (4) shared identity increases cooperation in economic policy areas.