How rearranging displays increased healthy drink purchases by 11%

Intervention Health

Abstract

This intervention attempted to address the increasing problem of obesity in Denmark through choice architecture.1 Researchers nudged students from four vocational schools towards healthier drinks by making unhealthy drinks less visible.  The first nudge moved unhealthy drinks towards the bottom of the cooler, whereas healthy drinks were at eye-level. This nudge increased the proportion of healthy drinks purchased by 11%. In the next phase of the experiment, the researchers added a secondary nudge: a frosted sticker over the unhealthy drinks section. However, this addition was insignificant in most canteens. Overall, the researchers concluded that the first nudge was successful, and should inform policies and the design of canteens in other educational settings.

Rating = 4/5 (Easy to implement; significant results; moderate consistency in results)

How drink placement decreased unhealthy purchases
Condition Results
Week 1: Control  33.3% of purchased drinks were healthy
Week 2: Unhealthy drinks at the bottom of the cooler  43.7% of purchased drinks were healthy
Week 3: Addition of a frosted sticker at the bottom of the cooler 44.6% of purchased drinks were healthy

Key Concepts

Nudges – interventions created to assist people in making choices in line with their own preferences without impeding their ability to choose freely. 

Choice architecture – The presentation of choices in different ways will impact decision making.

The Problem

Childhood obesity in Denmark

Obesity is a significant public health problem, which can lead to many serious physical health complications, as well as poor mental health and stigmatization.2  Obesity’s prevalence has been growing globally and Denmark is no exception. A 2017 report found that 10% of children in Denmark were overweight or obese.3 Although preventative measures are used, traditional methods like campaigns or food labels have had limited effectiveness in the past.1 One reason might be that people make less rational choices regarding food than we previously thought.1

Increasing healthy choices

Mikkelson et al. created an experiment based on our increasing knowledge surrounding choice architecture. Since the consumption of sugar-sweetened beverages (SSB) is associated with unhealthy weight gain and a higher risk of mortality, the researchers chose to target students’ choice of SSB over healthier options, such as water or milk.

Design

Past successes through nudging

The design of this intervention was based on the idea that nudges — aspects of choice architecture that change behavior in a non-forceful manner — can be used to promote healthy decisions. Nudge theory became famous in 2008 after the release of Nudge: Improving Decisions About Health, Wealth, and Happiness, by behavioral economist Richard Thaler and legal scholar Cass Sunstein. Since then, many studies have demonstrated that physical environments can influence food choices. For example, increased portion size has been shown to cause more food intake, while manipulating proximity and visibility has increased fruit and vegetable consumption among college students.4

The intervention: healthy beverage visibility 

Inspired by these successes, the creators of this intervention nudged students to make healthier drink choices by rearranging the location of beverages in the coolers of canteens of vocational schools. In particular, the researchers made SSBs less visible than the healthier option. The subjects of the experiment were vocational school students. Canteen managers collected data on beverage sales.

The intervention was pre-tested in a canteen at Aalborg University, which demonstrated that changing the visibility of drinks in coolers affected student choice.

The intervention phases

The intervention was rolled out in three steps:

  • Week 1: SSB located at eye height with high visibility (as it was previously)
  • Week 2: SSB in medium visibility at foot height
  • Week 3: SSB in low visibility at foot height with a frosted film covering the glass front

What is a healthy beverage?

Beverages were categorized as healthy or unhealthy in the following way:

  • Healthy = water, juice, skimmed milk, and smoothies
  • Unhealthy = SSB, energy drinks, and cocoa milk

The dependent variable being measured in the experiment was the healthiness of purchased beverages each week.

Results and application

Nudge 1: Higher healthy beverage take-up

Across three of the four vocational schools, the proportion of healthy beverages increased after the first intervention. However, in one of the schools, there was virtually no change in the proportion of healthy drinks chosen.  The researchers suggested this exception may have occurred because the cooler was less visible to students in this location compared to the other canteens.

Overall, the first nudge led to an 11% increase in total sales of healthy drinks from four canteens. The total sales of drinks remained almost identical, further suggesting that nudging worked to promote healthier drink choices.

Nudge 2: The null effect of frosted film

Across all canteens, the difference in sales between healthy and unhealthy drinks did not increase significantly between week two and three, with the exception of one school. This suggests that adding frosted film to the cooler wasn’t any more beneficial than the original nudge.

Furthermore, qualitative interviews demonstrated that some students felt the nudge was undermining their freedom of choice. As a result, the researchers recommend only applying the first nudge in school settings.

Overall, the study demonstrates that food choice is at least partially an automatic behavior that can be influenced through choice architecture. The researchers recommend that policymakers and schools take this into account when designing their environments. They also explain that this approach should not be limited to SSBs, but also other foods whose intake should be reduced.

Applications

Industry Application
Climate and Energy A study conducted in Sweden has found that changing the physical set-up of a waste sorting system can increase food waste sorting by 44-49%5
Health and Wellbeing  The importance of hand hygiene has been emphasized time after time throughout COVID. Watson and Driebelbis suggest that using environment change nudges can help promote student handwashing. Some examples of altering the physical environment included: ensuring handwashing facilities are directly in one’s path when exiting toilets and positioning them within view of others to increase social pressure.6 
Retail and Consumer Very similar to the current canteen study, another study found that placement of potato chips on the middle of shelves was associated with the highest percentage of purchases.7  Companies can use this information to manipulate sales to their advantage — so shoppers beware!

Ethics

  • Although consent was not demanded from the students, since only group sales data was collected with no possible identification of the individuals from the data, the experiment did not create any ethical violations.
  • Unfortunately, the intervention did not test whether the nudge would be successful in promoting healthy behaviors in the long term.
  • Since obesity can disproportionately burden certain populations, by including children of lower socioeconomic position, the study indirectly promotes a more equitable distribution of welfare.
Yes Room for improvement Insufficient information/Not applicable
Welfare
Does the intervention demonstrably improve the lives of those affected by it? Yes, all participants can benefit from a reduction in unhealthy drink purchases
Does the intervention respect the privacy (including the privacy of identity) of those it affects? Only group sales were reported, so researchers protected students’ privacy. 
Does the intervention have a plan to monitor the safety, effectiveness, and validity of the intervention? Although the intervention was safe and valid,  it would be interesting to see if healthier drink choices lead to an overall reduced calorie intake, since the overall goal is to prevent obesity. Additionally, as mentioned by the researchers, the intervention was relatively short, and it is unclear how well this nudge would do in the long term.
Autonomy
Does the intervention abide by a reasonable degree of consent? Although participants couldn’t consent, as no data was linked to individuals, consent  could have affected the results, due to the observer-expectancy effect.
Does the intervention respect the ability of those it affects to make their own decisions? Although all options of drinks remained available through-out the three weeks, the frosted film reduced visibility to an extent that bothered some students and made them feel their ability to make choices was threatened.
Does the intervention increase the number of choices available to those it affects? The drink choices available to students remained the same.
Equity
Does the intervention acknowledge the perspectives, interests, and preferences of everyone it affects, including traditionally marginalized groups? The experimental design wasn’t community driven. Student participation likely could have helped avoid the negative reactions to the second nudge.
Are the participants diverse? Diversity of the participants was unclear and depends on the diversity of students at the four vocational schools.
Does the intervention help ensure a just, equitable distribution of welfare? Obesity is unequally distributed in the Danish population. For example, children from a lower socioeconomic position are at a greater risk of developing obesity. Consequently, this intervention can help prevent the unequal distribution of the burden.

Related TDL Content

Nudging Can Encourage Sustainable Food Choices

In addition to promoting healthier food choices, nudges can also promote more environmentally sustainable food choices. Read this interview with Dr. Jolien Vandenbroele, a postdoctoral researcher in the Department of Marketing, Innovation, and Organization at the University of Ghent to learn how her team impacted consumers’ willingness to swap meat for non-meat substitutes.

Dr. Mitesh Patel on Nudging, Tech, and Health Care

Nudging gained traction very quickly in fields such as retail and entertainment; however, the highly regulated field of health care has been slower in adapting behavior science. This is starting to change rapidly though. Read this article with one of the key catalysts in the field, Dr. Mitesh Patel, as he discusses the opportunities that nudges, personalization, and technology can create for practitioners and patients.

Jesse Itkowitz: Nudging Against Polarization

In this episode of The Decision Corner, Senior Vice President and Behavioral Scientist at Ipsos Behavioral Science Center, Jesse Itkowitz, is interviewed by Jakob Rusinek from the World Bank’s Knowledge Management Unit. Their fascinating conversation touches on how to determine whether to nudge or not, nudging within advertising, and much more!

Sources

  1. Mikkelsen, B. E., Sudzina, F., Ørnbo, L. E., & Tvedebrink, T. D. (2021). Does visibility matter? – a simple nudge reduces the purchase of sugar sweetened beverages in canteen drink coolers. Food Quality and Preference, 92, 104190. 
  2. World Health Organization. (2017, October 10). World obesity day: Understanding the social consequences of obesity. World Health Organization. https://www.euro.who.int/en/health-topics/noncommunicable-diseases/mental-health/news/news/2017/10/world-obesity-day-understanding-the-social-consequences-of-obesity.  
  3. OECD Obesity Update 2017. OECD. (n.d.). https://www.oecd.org/health/obesity-update.htm.  
  4. Diliberti, N., Bordi, P. L., Conklin, M. T., Roe, L. S., & Rolls, B. J. (2004). Increased portion size leads to increased energy intake in a restaurant meal. Obesity Research, 12(3), 562–568. https://doi.org/10.1038/oby.2004.64.  
  5. Sand, H., et al. (2017), Nudging and pro-environmental behaviour, TemaNord, Nordic Council of Ministers, Copenhagen K, https://doi.org/10.6027/TN2016-553.  
  6. Watson, J., & Dreibelbis, R. (2020). (rep.). USING ENVIRONMENTAL NUDGES TO IMPROVE HANDWASHING WITH SOAP AMONG SCHOOL CHILDREN. UNICEF, Save the Children, WaterAid & Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH On behalf of the German Federal Ministry for Economic Cooperation and Development (BMZ). 
  7. Sigurdsson, V., Saevarsson, H., & Foxall, G. (2009). Brand Placement and consumer choice: An in-store experiment. Journal of Applied Behavior Analysis, 42(3), 741–745. https://doi.org/10.1901/jaba.2009.42-741.