Icons for health effects of cigarette smoke: a test of semiotic type.

We sought to identify icons to effectively communicate health harms of chemicals in cigarette smoke. Participants were a convenience sample of 701 U.S. adults. A within-subjects online experiment explored the effects of icon semiotic type: symbolic (arbitrary, most abstract), indexical, and iconic (representative, most concrete). Outcomes were perceived representation, affect toward smoking, elaboration, perceived severity, and perceived effectiveness. For not-easy-to-visualize harms of cancer and addiction, symbolic icons received the highest ratings (all p < .001). For easy-to-visualize symptoms of heart attack/stroke, indexical icons received the highest ratings (all p < .001). For easy-to-visualize harm of reproductive organ damage, the iconic image did best (all p < .001). Icon type often had a larger impact among participants with higher health literacy. Symbolic icons may be most effective for health effects not easily visualized. Iconic or indexical icons may be more effective for health effects attributable to specific body parts or symptoms.