Consumers often depend on salient cues to judge sustainability, even when these cues imperfectly reflect an offering’s true environmental impact. We demonstrate that adding visible eco-friendly components to offerings improves perceptions, whereas reducing or removing such components – despite potential sustainability gains – receives little recognition. We call this asymmetry the sustainable additive bias.

Across eight online and lab studies and one field experiment, we demonstrate the existence of this bias and uncover its underlying mechanism. Studies 1 and 2 show that companies are judged more sustainable when they add, rather than subtract, eco-components. Studies 3 to 5 confirm the bias for eco-friendly additions, but also show consumers recognize that component subtraction can improve sustainability in the case of non-sustainable components. Studies 6 and 7 suggest this bias effect is linked to perceptions of company effort. Finally, Studies 8 and 9 show this bias can be mitigated by prototypicality (i.e., whether a component is a typical example of sustainability). Overall, our findings highlight how environmental cues can mislead sustainable decision-making and be counterproductive to true sustainability; we describe implications of the bias and actions for its reduction.