Effect of visual aids and individual differences of cognitive traits in judgments on food safety

We examined the effect of visual aids on judgments on food safety in conjunction with individual cognitive differences. In this study, participants (nine hundred Japanese women) were presented with explanations of pesticide residue either in written form only or in written form accompanied by a visual aid (functional graph or illustration), and were asked to make judgments on safety for foods that have pesticide residue. Findings through a web-based survey showed that judgments on food safety were highly difficult for laypeople since they had little knowledge of the technical terms used to describe amounts of pesticide residue. We found that although a visual aid showing their functional relationship did not improve understanding of the technical terms, an illustrated visual aid led to both improved understanding and more accurate judgments on safety. We also found that although cognitive traits measured with the subjective numeracy scale (Fagerlin et al., 2007b) and the Cognitive Reflection Test (Frederick, 2005) correlated with judgments on food safety, the judgments were improved with the use of visual aids regardless of cognitive traits. These results show that while not all visual aids enhance understanding of food safety information, appropriately designed visual aids do, and that cognitive traits producing individual differences in judgments on food safety should be taken into account when considering how food safety information should be conveyed.