How effective are pictograms in communicating risk about driving-impairing medicines?

To evaluate and compare the effectiveness of 2 pictograms in communicating risk in terms of respondents' level of understanding, estimated level of driving risk, and intention to change driving behavior. The added value of a side-text was also investigated.

Two experiments were conducted among 270 drivers visiting a pharmacy. Experiment one used a 2 (rating model vs. triangle model pictogram, same side-text) × 3 (minor vs. moderate vs. severe driving risk) between-subjects design. Respondents (n = 30 per condition) were exposed to one of the 6 conditions. To verify the added value of the side-text, a 2 (rating model with side-text vs. rating model without side-text) × 3 (same categories as before) between-subjects design was used.

Although the majority of the respondents understood that the pictograms were related to driving behavior, less than 10 percent and about 36 percent of the respondents looking at the triangle model and at the rating model, respectively, understood it fully. For all categories of risk, respondents who saw the rating model pictogram associated the pictogram significantly more often with risk of medication intake for driving than those who saw the triangle model pictograms. Those exposed to the triangle model overestimated the driving risk of the lowest category and underestimated the risk of the highest category; 78.8 percent of the respondents stated they were (very) likely to change their driving behavior if they were confronted with the pictogram. The added value of the side-text was not confirmed.

Despite not being fully self-explanatory in conveying warnings and safety-related information, the pictograms evaluated in this research provided good insight into the different levels of driving risks, especially the rating model pictogram, because respondents' intentions to change their driving behaviors increased with higher categories of risk. The added value of the side-text in the rating model pictogram was not confirmed in this research. Pictograms can be seen as a valuable means to reinforce both written and spoken information given to patients by health care providers at the time of consultation.