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Many of us try to reduce our ecological footprints or to buy cruelty-free products. Still, our good intentions often disappear once we see the price difference between organic products and the 'regular' cheap alternatives. The increasing popularity of online supermarkets may provide ways to seduce customers to exchange their cheap mass-produced sausage for a more sustainable, organic or even a plant-based alternative. In this blog, we investigate some possible ways.

Supermarkets employ various strategies in order to let you buy more products than you originally may have planned. The vegetable section is typically near the entrance and aims to promise freshness and health during your whole shopping trip. Popular convenience items and snacks are often placed in the middle of the aisle, so that you can easily grab them. The most expensive brands are at eye-level, house brands are placed at the bottom. Music, the smell of fresh bread and several other elements influence your shopping speed as well.

Buying groceries online is a different experience, where users systematically browse and search for the products they need. Still, making use of recommendations and suggestions, supermarkets still try to stimulate you to buy products that you bought before or that they think you will like. In a similar way, supermarket customers could be made aware of the impact of their choices on, for example, water conservation and land management. However, attempts thus far with certification marks or other labels have had only limited success. Therefore, in our study, we aim to 'nudge' customers to (arguably) better choices.

Nudging techniques for choosing better alternatives

Suppose you just have chosen to exchange a regular sausage that would have costed for a more expensive organic alternative. Suppose you would then discover that the plant-based alternative is only 20 cents more expensive? Would you then consider to go vegan for today?

Or, alternatively, if you would have found the organic alternative too expensive and then discovered that the price of the plant-based sausage is cheaper than the organic one (but still more expensive than the regular sausage)? This might make going vegan even more attractive.

The first strategy is called the 'decoy effect' nudge: first, the customer is moved into the desired direction and then seduced to go one small step further. The second strategy is the 'middle-option' nudge, which speaks for itself. Both strategies may work with or without price information.

decoyoption middleoption1

Left: the decoy nudge, where customers are led to the vegetarian option via an organic product. Right: the middle-option nudge, where the key product is placed in the middle.

Shopping experiment

We asked 204 people to visit an experimental online supermarket to select potatoes, vegetables and a meat product or substitute for their evening meal. For the meat product, we randomly used the decoy or middle-option nudge, with or without price information, to nudge them via organic meat to the most sustainable, vegetarian option. As a baseline, some participants were not shown a nudge. We also asked them whether they usually would buy eco-friendly products.

The decoy nudge indeed stimulated customers to buy the most ecological, vegetarian alternative more often (an increase from 24% to 53%). The organic meat option was chosen slightly more frequent as well.

The middle-option nudge was just as effective in increasing the sales of the vegetarian alternative to 50%, but the nudge did not increase the sales of organic meat. Apparently, the decoy nudge managed to present both alternatives (organic and vegetarian) as attractive, whereas the middle-option nudge only managed to convince those who were willing to go vegetarian alltogether.

We also presented versions without price information. As expected, without price information the sales of organic meat increased slightly, even without nudge. As expected, both the decoy and middle-option nudges did not succeed in convincing participants to go vegetarian - as the decoy effects largely depend on the price.

Nudges for stimulating conscious shopping behavior

Our study confirmed that price does play a role in choosing between regular, organic and vegetarian alternatives, with some tendency to choose the cheapest option. However, the effects of the nudges were stronger. This would mean that - even though organic and vegetarian options are inherently more expensive - supermarkets can still convince customers to buy them. Our results show the effectiveness of direct comparison and pro-active suggestions at the moment that the customer makes a choice. We hope that this study will inspire supermarkets and other stores to experiment with new ways to guide customers to more sustainable choices.

This blog post is based on the master thesis "Digital Nudging Aspects Shifting Consumer Purchase Behavior to Become More Ecological in Web Supermarkets" by Wim Fechner, supervised by me and successfully defended in August 2020.

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Privacy Engineering, User Modeling, Personalization, Recommendation, Web Usage Mining, Data Analysis and Visualization, Usability, Evaluation

Dr. Ir. Eelco Herder
Associate Professor
Human-Centered Computing Group
Information and Computing Sciences
Utrecht University

Buys Ballotgebouw
Princetonplein 5
3584 CC Utrecht
The Netherlands