The science behind why we always pick the same meal deal

“It’s lunch, not a hobby.”

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With great shifts in politics, an accelerating digital revolution and climate change, one question has plagued me for years: when there are hundreds of potential lunch options, why do I always buy the same Pret sandwich? Why do I always buy the same meal deal? 

In a £20bn food-to-go industry, meal deals are now a staple of working life. Available in most supermarkets, they tend to consist of a sandwich, a snack and a drink for as little as £3. So embedded are meal deals in popular culture, that a tweak by a supermarket will make headlines in the tabloid press

In theory, the attraction of the meal deal is that it can be varied by simply choosing a different combination.  Even if we were to eat only meal deals at Tesco for lunch, there are literally thousands of possible combinations (that's binominal distribution for you) of the classic snack, sandwich and drink combo. Yet as I once again gather my Ploughman’s cheese sandwich, my prawn cocktail crisps and my Diet Coke, I wonder whether I am alone in being so risk-averse. 

A not-very-scientific poll (much thanks to all 36 people who completed it) confirms that I am not the only one who buys the same thing for lunch most days in the week. About 52 per cent of our poll participants said that they eat the same thing for lunch three to four days of the week. More than eight in ten said that they eat the same thing at least twice a week.  

The regularity and predictability of our eating habits is confirmed by Pret A Manger, which tells me that while salads and fruits are at their most popular on Mondays (and steadily decreasing each day of the week), their cakes and desserts are most popular on Thursdays. 

The answer for why we always pick the same sandwich for lunch, however, goes beyond simply sticking to our favourites. 
 
It’s a habit

Al, 31, who responded to my online survey, tells me that he's “resigned to having a below average lunch, but below average tuna seems somehow better than below average chicken, bacon, cheese et cetera.” But why, Al, is below average tuna better than below average chicken?

I pose this question to Professor Roy Baumeister, an influential psychologist who specialises in free will. He suggests that the “human mind is designed to form habits and doing things automatically which consumes less willpower and mental energy than making a free, authentic choice each time”. 
 
Dr Sander van der Linden, the director of the Cambridge Social Decision-Making lab, also speculates that habit must play a factor in why we always end up buying the same sandwich repeatedly. These habits can be “triggered by stable environmental cues”, he suggests. In other words, the meal deal section of every supermarket. 
 
Context matters
 
Outside a bustling Co-op just before the lunchtime rush, Tom Goodwyn, 31, tells me his daily meal deal routine. “I do my own work at lunchtime, so I buy a meal deal and then sit in a coffee shop to work. He will have a meat-feast roll as his sandwich at least twice a week.

Lunchtime routines such as this allow us to overlook the repetitive nature of these meals. This was made evident by a study which looked at two groups of people – those that always bought popcorn when they went to the cinema, and those that didn’t. 

In the experiment, the participants were taken to the cinema and (unknowingly) either given some fresh popcorn or seven day old stale popcorn. 

While those that didn't always eat popcorn at the cinema consumed less of the stale popcorn than fresh popcorn, the habitual popcorn eaters ate roughly the same amount. The quality did not matter to the habitual popcorn eaters. 
 
When this experiment was repeated outside the context of the cinema (in a small room with a TV playing), both groups of people reacted negatively and therefore ate less of the stale popcorn. In other words, context matters. It's the same reason you're OK with your same egg-mayo sandwich in the office, but want to try something new when you're working away from your desk. 
 
We are distracted 

Another regular theme in people’s comments were that they were too distracted by work to think properly about their meal choice. Several studies show that when we are distracted we are likely to fall back into habitual actions, as the distraction is likely to occupy much of our working memory. 

So if you're thinking about what you have to get done before the end of the day while you browse through the shelves at EAT, that may also be why you always pick up the same thing. 

Diversification Bias
 
A report on shopping trends by the Co-op in 2015 found that 27 percent of us now choose our meals as each day comes. This increasing trend to only shop for the day has led to us consuming less variety. Interestingly, this lack of variety can be explained by a phenomenon called diversification bias. Essentially we choose more variety (and think in the long-term) when we make decisions simultaneously, as opposed to making decisions sequentially. 
 
So if you made meal plans at the start of the week, you would likely plan for meals that vary the types of meats and veg you had for the week. Whereas when you decide your meals each day, your choices overall for the week will be far less diverse than had you made all your decisions at the same time. 
 
Decision Fatigue

The concept of decision fatigue has been fashionable for the last decade or so. It can be used to describe why after you spend two hours browsing through every website for that perfect coat, you feel utterly exhausted. Humans are only capable of making a finite number of decisions each day. It is why we form habits, so we can focus our attentions on the decisions that really matter. 

Most notably, leaders of the business and political world such as Mark Zuckerberg and President Barack Obama have used decision fatigue to explain their decision to wear the same style of clothes each day. We mere mortals have the meal deal. 

Hunger affects our decision making

Intriguingly, studies have also shown that small amounts of glucose can counter the effects of decision fatigue. Perhaps your low-glucose levels before you have lunch is contributing to why you take two minutes to stare at your meal-deal options, before opting for the same thing you always eat. 

While it is unlikely any one of these reasons is the only reason you really just seem to like Pret's posh cheddar sandwiches, all of these cognitive biases add up. Then again maybe I've just overcomplicated things. Perhaps there is a more obvious answer, such as the one suggested by John, 42, in my survey: “By the time you've worked out which three sandwiches you actually like, after five years or so there's little point in trying to surprise yourself. It's lunch, not a hobby.”

Jason Murugesu is a postgraduate student in science communication at Imperial College London, and a former Wellcome Scholar at the New Statesman.

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