By guest blogger Freddy Parker

Fast food chains are not exactly renowned for encouraging healthy eating. But in a new study a team of psychologists, eager to turn that assumption on its head, chose McDonald’s as their target for a somewhat unconventional, psychologically-informed health intervention. Writing in Psychology & Marketing, the researchers report successfully “nudging” a group of Coca-Cola-guzzling customers into opting for its sugar-free counterpart, Coke Zero — simply by changing the order of options on the menu.

We like to think that our choices as consumers are completely under our own control — but researchers have shown that the location of a product on a list or display can subtly influence whether we decide to buy it. To examine this phenomenon in a real-world setting, Kelly Ann Schmidtke from Manchester Metropolitan University and colleagues sought to manipulate soft drink positions within the McDonald’s digital menu and see whether this could “nudge” people into making healthier choices (for those wondering, a nudge is any way that alters behaviour without forbidding options or using economic incentives).

Before the intervention, soft drinks were presented on the kiosk touchscreens in the following : Coca-Cola, Diet Coke, Coke Zero, Sprite Zero, Oasis and Fanta. The team theorised that presenting Coke Zero in first place would cause customers to choose this healthier offering. Normally, their logic went, customers expect the first location to hold the most popular drink, formerly Coca-Cola. But even when this turns out to be Coke Zero, they would still opt for this choice without considering additional items (psychologists term this kind of behaviour “satisficing”). So, for 12 weeks across 622 stores, the team swapped Coke Zero from the third location to the first, and put Coca-Cola in the last position.

Of the 511 stores with sufficient sales to be included in the analyses — those that had sold at least one of each type of soft drink each week — purchases of Coca-Cola fell by 9% on average in the first week of the intervention (translating to about 34 fewer sales per store), while sales of Coke Zero increased by 21%. The menu change continued to bear fruit for the entire 12 weeks, with sales of Coke Zero increasing by 30% and sales of Coca-Cola falling by 7% compared to the 12 weeks before the study, representing a reduction of about 345 sales of Coca-Cola per store. A back-of-the-envelope calculation puts the total calories removed from customers’ diets at just below 25 million.

It is not difficult to envisage how, when extrapolated to greater timescales and store numbers, this intervention could potentially have a huge impact on cola-eyed consumers’ health.

Notably, however, information was not collected from consumers about their feelings towards the intervention — indeed, it was not even clear if consumers were consciously aware of the manipulation at all. That’s important because although some research suggests that nudges to promote healthy food choices are generally considered acceptable, other studies have documented “reactance” wherein individuals feel an urge to defy the system once aware of nudges in place. Psychologists are still trying to understand the conditions that might initiate reactance to any particular intervention, so policymakers and fast-food-chain managers alike must be careful when implementing nudge designs to avoid provoking unintended negative reactions. Nevertheless, McDonald’s did not receive many complaints and continue to use the new item positioning to this day, the authors report.

These findings support calls for managers and policymakers to consider how physical layouts of food joints can influence expectations, and how knowledge of these expectations might be used to improve public health. Despite the role habits often play when making food choices, this study shows that nudges can be used to intervene where appropriate. The appetite for behavioural economics continues to grow.

– Menu positions influence soft drink selection at touchscreen kiosks

Post written by Freddy Parker for the BPS Research Digest. Freddy is a long-standing reader of the Research Digest and student at the University of Bath, studying for his final undergraduate year in Psychology.

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