Designing Smarter Nudges: Cognitive Load Theory in Sustainable Checkout Choices

E-commerce's exploding "last-mile" deliveries already emit millions of tons of CO₂, yet checkout interfaces still treat home drop-off as the default. While sustainability nudges can redirect orders to lower-carbon pickup points, designers lack evidence on how much information such prompts should convey- a critical gap, given shoppers' limited cognitive bandwidth. Grounded in Cognitive Load Theory, the author predicts an Inverted-U link: moderate message complexity maximizes click-and-collect uptake, but richer detail overloads working memory and backfires. A first empirical test— re-analyzing a public field experiment with 980 observations—supports this curve. Two additional studies (a lab and a field experiment) are planned to confirm causality, trace the mediating role of cognitive load, and probe age and internet-literacy boundaries. The work pinpoints a lean "sweet spot" for green checkout cues and offers an adaptive, skill-aware blueprint for cutting last-mile emissions.