Using Analogies to Communicate Information about Health Risks

Summary: Analogies are often used to explain health-related concepts in medical practice, but it is unclear whether they actually improve understanding and, if so, why. Here, we studied these issues in experiments on probabilistic national samples in two countries, focusing on two questions. First, we investigated whether analogies are helpful in communicating medical information to people with different levels of numeracy and for tasks of different levels of difficulty. Second, following existing theories of analogies, we studied what characteristics of analogies improve their helpfulness. Our results revealed that for difficult medical problems, analogies were helpful to high-numeracy people but less so to low-numeracy people. For easy medical problems, the results were reversed. Different analogies were successful in different cultural contexts. In accord with theoretical expectations, the most helpful analogies were those with high similarity of the relationships between objects in their target and base and those with highly familiar bases. Copyright © 2012 John Wiley & Sons, Ltd. Many patients have little understanding of basic statistical concepts—such as probabilities and the notion of a random toss—that are prerequisites for understanding information about the risks and benefits of health-related behaviors and medical treatments (Lipkus & Peters, 2009). As a consequence, they are at risk of making inadequate health-related choices and in turn of suffering illness and having higher mortality (Reyna, Nelson, Han, & Dieckmann, 2009). Visual aids can improve understanding in patients with low numeracy who understand basic graphs (Gaissmaier et al., 2011; Garcia-Retamero & Galesic, 2010). However, a significant portion of the general population—up to one-third—lacks the basic skills required to understand both numerical and visual formats (Galesic & Garcia-Retamero, 2011b). Therefore, it is crucial to explore alternative ways to communicate medical information to this particularly vulnerable group of people. Here, we investigate a method that may improve understanding of complex medical information even in patients that lack basic numeracy and graph literacy: using analogous examples from everyday life (Galesic & Garcia-Retamero, 2011a; Sopory & Dillard, 2002). Analogies, metaphors, and related figures of speech compare objects from different domains to illuminate some of their aspects (Holyoak, Gentner, & Kokinov, 2001). To illustrate, consider the following analogy that a doctor might use in medical practice: ‘Cancer screening is to cancer as a car alarm is to car theft’. The analogy explains the relationship between cancer screening and cancer (the target of the analogy) by means of the relationship between car alarm and car theft, one that is well grounded in everyday experience (the base of the analogy). The relationship that holds in the car domain— the fact that a car alarm sometimes signals theft but sometimes gives false alarm or does not activate when it should—is applicable to the cancer domain as well. Analogies have long been used in science education to explain a wide range of concepts (Oppenheimer, 1956). For instance, Mintz and Ostbye (1992) used analogies from legal practice to explain statistical concepts to medical professionals. Boyle, Robinson, Heinrich, and Dunn (2004) explained the complexities involved in a team approach to cancer treatment by comparing it to a rugby game. Newby, Ertmer, and Stepich (1995) successfully used analogies to improve understanding and recall of advanced physiological concepts. Halpern, Hansen, and Riefer (1990) used the analogy of judges who make and dissolve marriages to explain the workings of enzymes in the body. Doctors have been using analogies to explain medical concepts to patients since the dawn of medicine. As Edwards (2003, p. 749) illustrated, one doctor used the following story to explain the limited