Consumers credit visible green additions over unseen waste cuts across nine studies

The authors trace the bias to visibility. "The problem is that adding something is visible, while removing something is not," said Dr. Diletta Acuti of the University of Bath School of Management ^[6]. When a business removes products to save resources, she said, "customers cannot see what is no longer there, so that action may receive much less recognition" ^[7].

The 302-guest hotel experiment compared a room with a larger selection of eco-friendly amenities against one with a minimal set ^[4]. In our view that is the contrast a hotel creates when it trims its miniatures, so the test sits close to a decision hotels actually make.

The researchers report two ways to shrink the bias: clearly communicating the environmental effort behind a removal, and keeping highly recognizable signals such as refillable bottles or reusable products ^[5]. Acuti's example is a swap of "several miniature toiletry bottles with one clearly labeled refillable dispenser" ^[8]. The researchers add that hotels should explain removed amenities so guests understand that having fewer products is a deliberate sustainability measure ^[11].

Acuti's other worry is the giveaway. "Reusable cups, water bottles and tote bags can all be good alternatives to disposable products, but people increasingly have cupboards full of them," she said ^[9]. Her own tally: "I have accumulated around 20 tote bags myself, many given away at conferences and events" ^[10].

We think the advice to label removals follows from these findings, on one condition: the outcome measured is how sustainable people judge a business to be ^[1]. The thing this doesn't tell you is whether a higher rating changes what guests book or buy, and the phys.org write-up leaves out the field study's result and the effect sizes.