Green versus Grey Framing: Exploring the Mechanism behind the Negative Footprint Illusion in Environmental Sustainability Assessments

Given the complexity of assessing the environmental sustainability of products, consumers rely on cognitive strategies to simplify complex information and develop quick judgments, often referred to as heuristics, when processing eco-information. One of these heuristics is called ‘the Negative Footprint Illusion’: Consumers erroneously estimate the total environmental impact of a combination of a green and non-green product as lower than the same non-green product alone. In this research, we test this bias and explore its underlying mechanism. We evoke a more summative vs. more evaluative mindset by framing the response scales negatively (in terms of environmental damage, referred to as ‘grey scaling’) vs. positively (in terms of environmental friendliness, referred to as ‘green scaling’). This is carried out by using an online between-subject experiment in which respondents either respond on an evaluative response scale (green scaling), or a summative response scale (grey scaling). A hamburger and bio-apple were used as stimuli (either shown together or apart). First, the results show that the negative footprint is only apparent in the green scaling condition. Second, respondents who score higher on environmental concern show a stronger negative footprint illusion for the green scaling condition. Our study not only elucidates the cognitive mechanisms driving the negative footprint illusion but also offers strategic directions for both theoretical advancement and practical applications in environmental decision-making, highlighting effective ways to mitigate this bias.