Abstract
Risks can be explained to patients in narratives, numbers, or graphs. All these methods depend upon description. However, decisions from description differ systematically from decisions about risks that are experienced through activities such as drawing cards from a deck. We have developed a dynamic graphic interface that provides a virtual experience of event probabilities, with potential applications in patient education and decision support.
Background
Clear communication about risks is crucial in shared decision-making, informed consent, health promotion, and other health contexts. Risks can be described in narratives, numbers, or graphs. Unfortunately, all 3 forms can produce reasoning biases that complicate risk communication.1–4 Patients’ comprehension can also be impaired by educational factors such as numeracy.5 Decisions from experience differ systematically from such decisions from description, according to experimental decision research. For example, people overweight rare events when they read described probabilities, but assign them much lower weight when they experience probabilities through an activity such as drawing cards from a deck.6,7 Decisions from experience may exploit associative learning and thus may be less affected by learned numeracy skills.
Objective
To develop and test a set of dynamic probability graphics in a diverse population, with the goal of producing an e-tool for educational, informed consent, or decision support systems.
Development
We developed a JavaScript application to generate grids of figures with those affected by disease in a darker color. Users interact with the display repeatedly to sample populations to see how many are affected. Users can also view a blank array and click on any icon to see if it will be affected by the disease. The interaction and repetition provide a virtual experience of the event probability. The application has undergone heuristic usability evaluation by 3 experts. Qualitative interviews and usability analysis will be conducted in the Usability Lab of the Harlem Health Promotion Center with members of the public.
Experimental methods
IRB approval has been granted to test the application in a decision-making study. Users (recruited from the Harlem center and online through the Virtual Lab of Columbia’s Center for the Decision Sciences) will be randomized to view the displays or static graphs, and will complete a web-enabled survey about quantitative and qualitative risk perceptions. Demographics, numeracy, and computer familiarity will be assessed.
Expected results
On the basis of the literature, we predict that allowing participants to experience the probability of rare events by drawing repeated samples will tend to lower perceived risks and quantitative risk estimates, whereas describing the probabilities through static graphs will produce higher perceived risks and higher, less accurate risk estimates. We also expect interactions with the arrangement of the icon figures (random versus sequential arrangement) and user characteristics (high versus low numeracy).
References
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