Touchscreen menus at McDonald's have been 'tricking' customers into choosing healthier options, it was claimed today.
The fast food giant is well-known for its calorific Big Macs, French fries and milkshakes.
But an academic study has found that the introduction of the touchscreen order kiosks persuaded customers to choose less sugary options.
The revelation came when the company changed the positioning of the soft drinks in the menu list.
The button for Coke Zero was moved to the top left in 622 stores for 12 weeks in 2016.
Researchers found that sales of Coke Zero, which contains no sugar, increased by 21 per cent.
Meanwhile, sales of Coca Cola, which contains 170 calories for the medium size and 42 grams of sugar, fell by 9 per cent.
The researchers, from the Universities of Warwick and Manchester, found that sales of Coke Zero increased and Coca Cola decreased overall by more than 300 drinks per store.
The authors believe that by changing the order and listing a healthier item first, the customer has a chance to reconsider their choice.
McDonald's unusual international menu
McDonald's unusual international menu
An Ikasumi (squid ink) burger from McDonald's Japan is pictured at one of its fast-food outlets in Tokyo October 8, 2014. McDonald's Japan has launched the Halloween-themed black burger, which have buns made from a flour mix of bamboo charcoal powder and black sesame to create the charred look, and beef patties marinated with squid ink sauce. The burger is priced at 370 yen ($3.40) each. REUTERS/Toru Hanai (JAPAN - Tags: BUSINESS FOOD SOCIETY)
These McDonald's international items are now available in the U.S.!
Top 10 Exclusive McDonald's International Menu Items
From customer Lim Wan Ting: "Ordered a black pepper mayo chicken burger meal. The chicken is missing from the burger."
(Photo: Lim Wan Ting/Facebook)
From customer Kelvin Teo: Where is the patty?
(Photo: Kelvin Teo/Facebook)
Uggh, McDonald’s. Home of the flattest and most-non-burger tasting (but best ever) burger. McDonald’s food only vaguely reminds you of actual meat...
對不起，鴨鴨錯了，原來由麥當勞與 nanoblock 合作 crossover 推出的 McDonald’s Food Icons x nanoblock，是今期在麥當勞惠顧任何食品加 HK$20 去換購的五款經典美食潮流擺設，不可以食用的。可以食用的，是由即日起至 6 月 24 日以經典滋味價 HK$26 及 HK$31，與脆薯皇一起推出超值套餐，讓大家重溫麥當勞跨時代的經典口味的 Big Mac 與及 Mega Mac 才對。衷心希望不會有朋友因為看得太快，已經將 nanoblock 放進肚子了吧…（誤很大！） 除了 Big Mac 與及 Mega Mac 之外，很多朋友喜歡的熱焦糖新地，將會聯同全新的熱焦糖 Double 新地以及熱焦糖新地蘋果脆一起登場。 … 閱讀全文
Berlin, Germany - December 9, 2014: MC Donalds Bag at Alexanderplatz in Berlin - Germany. The McDonald 's Corporation is an American provider of globally active fast-food restaurants and the best-selling fast food chain in the world .
MIAMI, FL - APRIL 25: McDonald's crew member Samantha Medina prepares french fries as the McDonald's restaurant stock price reached record territory on April 25, 2017 in Miami, Florida. The company continues to beat expectations and credits changes to its menu and other new initiatives it has launched. (Photo by Joe Raedle/Getty Images)
FILE- This Aug. 8, 2018, file photo shows electronic menus at McDonald's flagship restaurant in Chicago. Robots aren’t replacing everyone, but a quarter of U.S. jobs will be severely disrupted as artificial intelligence accelerates the automation of today’s work, according to a new Brookings Institution report. The report published Thursday, Jan. 24, 2019, says roughly 36 million Americans hold jobs with “high exposure” to automation, meaning about 70 percent of their work tasks could soon be performed by machines using current technology. (AP Photo/Nam Y. Huh, File)
FILE - This Thursday, Jan. 28, 2016, file photo shows a McDonald's McGriddle sandwich in New York. McDonald's says it will expand its all-day breakfast menu with the addition of McGriddles nationally starting in late August. The company is hoping to continue momentum from the launch of a limited all-day breakfast menu from 2015 as it tries to revive slumping sales. (AP Photo/Candice Choi, File)
SAN FRANCISCO, CA - NOVEMBER 03: A McRib is seen at a McDonald's restaurant on November 3, 2010 in San Francisco, California. The sandwich arrived on the menu for the first time since 1994 and is offered at all McDonald's nationwide for a limited time until December 5, 2010. The McRib was first introduced in 1981. (Photo by David Paul Morris/Getty Images)
A cheesy champignon angus burger is seen at a McDonald's restaurant in Hong Kong July 27, 2017. REUTERS/Bobby Yip
This Aug. 8, 2018, photo show an electronic menu at McDonald's flagship restaurant in Chicago. (AP Photo/Nam Y. Huh)
This Aug. 8, 2018, photo shows electronic menus at the McDonald's flagship restaurant in Chicago. (AP Photo/Nam Y. Huh)
This Thursday, Jan. 28, 2016, photo, shows a McDonald's McGriddle sandwich in New York. McDonald’s plans to push its operational limits by testing the addition of the McGriddle to its all-day breakfast menu. The move comes after the company reported its biggest U.S. sales jump in nearly four years, following the launch of all-day breakfast in October. (AP Photo/Candice Choi)
This Monday, Jan. 4, 2016, photo, shows a "McPick 2 for $2" deal at a McDonald's restaurant in New York. Another price fight is breaking out among the country's biggest burger chains, this time with meal combos designed to make people forget about the once ubiquitous dollar menus. (AP Photo/Candice Choi)
Pictured is the exterior of a McDonald's Angus Third Pounder hamburger in carton purchased at a Chicago area McDonald's fast food restaurant Friday, March 1, 2013, in Chicago. McDonald's is getting rid of its Chicken Selects and Fruit & Walnut Salad and is considering the removal of Angus burgers. The change up comes as the world's biggest hamburger chain plans to step up the number of limited-time menu items in the year ahead. (AP Photo/Charles Rex Arbogast)
Pictured is a McDonald's Angus Third Pounder hamburger in carton purchased at a Chicago area McDonald's fast food restaurant Friday, March 1, 2013, in Chicago. McDonald's is getting rid of its Chicken Selects and Fruit & Walnut Salad and is considering the removal of Angus burgers. The change up comes as the world's biggest hamburger chain plans to step up the number of limited-time menu items in the year ahead. (AP Photo/Charles Rex Arbogast)
LISBON, PORTUGAL - SEPTEMBER 4: McDonald's restaurant digital menu boards self-serve kiosks with touch screen in passenger area at Terminal 1 of Humberto Delgado International Airport on September 04, 2018 in Lisbon, Portugal. Portuguese tourist industry has gone through an excellent year in 2018, for the country is rated as very safe by travelers. (Photo by Horacio Villalobos - Corbis/Corbis via Getty Images)
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The customer expects Coca-Cola to be in one place but is then prompted to reconsider 'their otherwise habitual menu choice', according to the findings.
Dr Ivo Vlaev, a behavioural scientist from Warwick Business School and co-author of the study, said it was 'shocking' that such a large change had been observed.
'You can call it a cognitive trick. 'It's based on a bias, or a psychological blind spot we have when we are looking at the range of options in front of us or the world outside of us, because we focus our attention on things that are more salient, or are immediately coming in front of us,' he said.
'Our eyes follow certain patterns when we are looking at the world, as when you're reading a page in a magazine.'
The researchers initially worked with McDonald's, which funded the study, to make Coke Zero the 'default' choice when ordering a meal.
But they were not able to do this because some people are allergic to the sweeteners used to replace sugar.
The study shows that changes can be made without affecting businesses' profits, and shows how industry can be a conduit for public health messages.
'You can make a big difference by small changes at the right time and place,' Dr Vlaev said.
'It doesn't need to be complex, you can replicate what we did with McDonald's.'
'It's a win-win if you do it the right way, and behavioural science could be the tool to find such a win-win situation.'
The study was published in the journal Psychology & Marketing.