One approach to making statistical information more understandable in a medical context is the visual representation of health risks. An example of such visualizations are icon arrays. Icon arrays are matrices of often 100 or 1000 symbols representing a potentially at-risk population. In practice, however, icon arrays often differ in their design characteristics. The aim of this study was to investigate the influence of different icons and colors on the perception of medical risks. In particular, little is known about the effect of color in icon arrays.
The results showed that the use of different icons (person icons vs. smiley icons) and colors (black/white vs. red/yellow) had no effect on the perception or recall of a 10-year cardiovascular risk estimate, i.e. the risk of having a heart attack or stroke. There was also no difference between the visualizations in terms of emotional response or intention to reduce risk through health behavior change. However, participants preferred the person symbols over the smiley symbols.
The results suggest that the icon arrays may be equally suitable for communicating medical risks, such as the results of cardiovascular risk calculators. The results were consistent for individuals high or low in numeracy and for individuals with or without a history of cardiovascular disease. Guidelines for the design of visual aids could benefit from these findings, as there are currently no specific recommendations for the use of color.