Environmental impact judgments of meat, vegetarian, and insect burgers: Unifying the negative footprint illusion and quantity insensitivity

Climate-related risks for natural and human systems increase with global warming. Meat production contributes considerably to global greenhouse gas emissions. Changes in consumption patterns can help reduce this impact - e.g., by replacing meat with plant or insect-based alternatives. For this to happen, it is important to understand how such products are perceived in terms of their environmental impact. Two cognitive biases - the negative footprint illusion and quantity insensitivity - have been shown to affect this perception. The present study (N = 501; M-Age = 47.8, SD = 16.8; 48.9% female) tries to replicate both biases in the context of meat, vegetarian, and insect burgers. In an online experiment, participants viewed pictures of a variety of meals and rated their environmental impact on a carbon footprint scale (between-subject design). We found that footprint ratings of a prototypic fast food meal consisting of fries, water, and either a vegetarian or an insect burger did not significantly differ from the ratings given to the meal without the burger (negative footprint illusion), while the addition of a meat burger increased the rating. Furthermore, we found that participants' judgments were insensitive to the quantity of the presented burgers, and they reacted only to the type of the burger patty (quantity insensitivity). We did not find that green consumer values - the tendency to express the value of environmental conservation through one's purchase and consumption behavior - influenced the estimation. Throughout all conditions, beef burgers consistently received higher footprint ratings than vegetarian and insect burgers. While we could not strictly replicate the original results, we conclude that our findings are still consistent with previous studies and can enrich the understanding of the underlying cognitive processes causing them. Specifically, we propose that both biases can be attributed to the same general-purpose heuristic of intuitive judgment - namely, attribute substitution, and the prototype heuristic in particular.