Effects and interactions of labels? color scheme and the individual difference variable lay rationalism on pro-environmental choices

Recent eco-labeling research suggests that labels that use traffic light colors to communicate an evaluation of product attributes are more effective in guiding consumer choices toward environmentally friendlier products than those that merely provide quantitative information. However, it remains unclear whether the effect of traffic light labels is attributable to the additional information provided by the colors or whether the colors themselves impact consumer choices. We investigated the influence of labels' color scheme on consumers' preferences for environmentally friendly electricity. In two experiments, participants chose between electricity products differing in price and carbon emissions. The products had labels based on either traffic light colors, grayscale colors, or text (Study 2) to classify carbon emissions as low, medium, or high. Furthermore, we used the lay rationalism scale to assess participants' tendency to base decisions on feelings versus reason. The two main findings were that traffic light labels increased the choice share of low-emission electricity relative to text-based labels but not relative to grayscale labels, and that there is an interaction effect between labeling format and lay rationalism. Another finding is that both emotional affinity toward nature and guilt proneness are strong predictors of preference for low-emission electricity. Our data underline the importance of examining different label formats and further suggest that labels should be designed according to a target group's decision-making style.