Interview with an Oxford Food Psychologist

Posted by Meghan Rossi on May 2, 2019 in Neuroscience of appetite, Perception, Sensory Systems | Leave a comment

The surprising ways our brains steer our eating experiences, and how to use them to our advantage

According to Dr. Charles Spence, when it comes to experiencing food, taste is the least important factor. But can that really be true? To learn about food psychology – or how our brains process multisensory information about what we eat and drink – we arrived on a sunny spring day outside Dr. Spence’s flat in Jericho, a trendy neighborhood lined with redbrick Victorian houses and buzzing gastropubs just north of the center of Oxford. He ushered us in, leading us downstairs with a jovial trot into his glass-walled study. Dr. Spence is, seemingly, a jack of all trades: professor of experimental psychology at the University of Oxford, head of Oxford’s Crossmodal Research Lab, energetic bon vivant, consultant for behemoth food and beverage companies like Pepsi, and enthusiastic collaborator with prominent chefs including Heston Blumenthal – a London-based Michelin-starred celebrity chef and UK household name. Sunlight and the sound of buzzing insects filtered in through the open windows while Dr. Spence told us about all things food psychology: from strategies to encourage insect-eating, to helping cancer patients enjoy their food despite suffering from metallic tastes.

Tell us about your recent experiments with Heston Blumenthal. I’ve been working with Heston since about 2003 when he first came to the lab in Oxford. We do experiments with his chefs looking at everything from food and meal design and plating to, on occasion, training the front and back of house staff to describe how the brain processes flavor when discussing dishes with the diners. Some of what we’ve been working on is the shape of foods and how they’re arranged on a plate. We did an experiment where the Fat Duck [Heston Blumenthal’s Michelin 3-star restaurant] team made some beetroot jelly, and they either served it on a round plate as little semi-circular round balls, or they served it onto angular plates with the jelly made into angular pyramid shapes. Everyone got to taste the same jelly, but those who tasted the angular jelly thought it tasted more sour, and those who tasted the rounder jelly thought it was more sweet. This backs up our lab research, and also shows how the chef might use that plating strategy to potentially serve something with less sugar but with the same taste.

How else can we change food to make it healthier, but trick ourselves into thinking that what we’re eating is maybe a bit sweeter than what it is? Well, a lot of food companies have the problem that, either of their own volition or on instructions from the government, they’re being told to reduce sugar, salt, fat, and other “less healthy ingredients” shall we call them. But, when they do that, very often consumers will complain, “What have you done to my favorite brand? It’s not the same as it was, give me it back!” So companies have to evolve different strategies to improve the composition of their product without consumers necessarily knowing that they’re being changed. For example, we’ve seen breakfast cereal manufacturers gradually reduce salt, month-by-month, year-by-year, so that, from one month to the next nobody notices a difference, but if you compared today’s cereals to those of 3 years ago, they’re 10% lower in salt or more. That’s kind of a “health-by-stealth” approach, which does work, but it takes a long time.

It’s almost as if people can’t separate the product from a pack, and what they think about the pack carries over to influence their perception of the product.

Others are thinking about how to use psychological tricks: if you know how the mind works and how it constructs flavor perception, you can change the design of the product, or, increasingly, the pack in which it comes in order to deliver something that has less of the unhealthy stuff but the same perception in the mind. Take the weight of the packaging. We’re doing studies in the lab and in restaurants where, if you just drop a weight into the bottom of a yogurt pot, or underneath a can of soft drink, then people will rate the product as better. And, if it’s yogurt, they will rate it as more filling. It’s almost as if people can’t separate the product from a pack, and what they think about the pack carries over to influence their perception of the product. It could be the weight of the packaging, it could be the texture of the packaging, it could be the color of the packaging. If you change the color of a can, it can change people’s perception of the sweetness or the taste of the contents too.

We know in the short-term it works, but quite how long some of these effects last, we don’t know. We have submitted grant applications to look at, say, if you had your coffee out of a red mug every day for a year rather than a white one – and I know, for instance, that the red mug makes things taste sweeter – would it still taste sweeter at the end or would your brain just learn “hold on a minute, there’s something not quite right here” and adapt in a way? Our brains do seem to adapt, for example to low-fat processed ready-meals. Initially, people lower their weight a bit, but then after a month or two the brain’s figured out it’s not getting what it wants, and then you start eating more and your weight goes back up. So it seems there are some of these tricks that will last in the long term, others that won’t.

In our hands, we can add up to 10% sweetness just by changing the shape and color of the plate.

Are there other ways to alter sweetness without changing the actual composition of the food or drink? We did some research with Ferran Adrià in his test kitchen just outside Barcelona back in 2012, showing that exactly the same strawberry ice cream was rated as tasting sweeter when served on a round, white plate rather than on a round, black plate. Paul Bocuse’s cookery school and restaurant in France has also found that round and white is sweeter than angular and black. In our hands, we can add up to 10% sweetness just by changing the shape and color of the plate.

You can also manipulate the background music. We had a dish that came out of collaboration with the Fat Duck that was served at the House of Wolf restaurant in Islington a few years ago: the sumac cake-pop, which was a bittersweet chocolate lolly. The diners were encouraged on the menu to dial up one of two telephone numbers on their mobile device. If they dialed 1, they heard a high-pitched tinkling sound, and if they dialed 2, the soundtrack was a low-pitched rumbling sound. Research with the Fat Duck and here in the lab in Oxford showed that you can get about 5-10% sweetness just by the sounds in the background, with higher pitches being perceived as more sweet and lower pitches as more bitter. Sounds really shouldn’t affect the flavor, but they do! I think these are all small nudges; each one not huge, but maybe when you add them up, they could have some sort of beneficial effect.

As a chef, could you make metallic taste into a desirable food sensation?

What about cancer patients who suffer from metallic sensations when they eat? Can we change hospital food for these patients to encourage them to eat more? We’re now working with a very forward-thinking hospital in Barcelona to see if you can take the modernist chef’s techniques and tricks, along with the psychologist’s, to eliminate those metallic tastes. We as humans love eating some disgusting stuff, like French cheeses and things. They smell vile but we still like it – it’s clear we can get to like anything. As a chef, could you make metallic taste into a desirable food sensation? As long as the first time you experience it isn’t in the hospital, then perhaps it could even become a preferable sensation. Then when you get that taste in the hospital, you could respond to it differently. A financial case can certainly be made that, by improving the quality of food, you can get people to eat more, equating to a reduction in bed nights.

I saw that your lab is interested in potentially using these “psychological tricks” to promote insect eating. Though eating bugs isn’t well accepted in our society right now, could we maybe use these tricks and packaging techniques to somehow make it more palatable? Hmm, I’m not sure if I’ve still got any bee brood ice cream in the fridge – I think it’s waiting for this year’s baby bees. Our chef lives in the house and brings his father’s unused male brood back for ice cream and chocolate ganache, which is very good! So yes, given everything we know, can we use that for the biggest challenge of them all, which is nudging people towards thinking of bugs as desirable? It’s a big psychological problem, and the World Health Organization suggests we should be moving in that direction and doing so fast.

We are doing experiments now where you’re shown a picture of a dessert made out of insects, and we show it either as a full-on modernist dish or deconstructed into its elements, and we’re also playing with the labeling. You might see that dish on the computer screen, described either as an “insect product,” or a “bee product,” or also as “an environmentally-friendly source of protein,” and then we see how the labeling and the presentation might change how much you’d be willing to eat it. Of course, that experiment is on a screen so you’re never actually going to have to eat it. But we also do experiments at food festivals and Food Matters Live [annual showcase of food technology innovations in London] giving people biscuits that they’ve been told might contain insects. In that case, it never did because we didn’t have the ethics in time, but we wanted to see how even the belief that you might be eating insects could change things.

What we found, with Ben Reade [Scottish chef, former head of culinary research at Nordic Food Lab in Copenhagen, co-founder of Edinburgh Food Studio] who is big on insect eating, and Ophelia Deroy [philosopher at the Centre for the Study of the Senses, London], is that all the approaches that have been used so far saying, “you should eat insects as they’re good for the environment,” “they’re rich in protein,” all of those sorts of arguments don’t work because people don’t eat things because they’re told they should eat them.

We’re suggesting that the best way in is to actually use the “bugs by stealth” route. If you like peanut butter, that’s actually got up to 100 insect parts per 100g already. Fig jam, no doubt even more. So, for a number of products, a certain amount of bugs are allowed to get in the mix without you having to declare them, so they are there, you’re eating them already, you just didn’t realize. So you could imagine if now it’s 100 bug bits per tub of peanut butter, next month it’s 110, and then by next year we were having 2,000 bug bits, then we’re all eating insects without anyone ever having to make that kind of conscious choice.

The other way to do it is to actually accentuate it and say these are wonderful-tasting products. Not all of them – the bugs that look beautiful taste horrible, in fact it’s probably the ugly ones you want to aim for. But they have some unique flavors, some unique mouth feels, and we’re working with chefs like Jozef Youssef [chef and founder of Kitchen Theory] and Ben Reade and his colleagues to see how the modernist chef will take the insects and turn them into a desirable thing. We’re working with people who are coating locusts in gold, drawing your attention to them.

At Jozef’s former pop-up restaurant Synesthesia in London, you’d get a bread roll to start the meal, and on one side of the slate there is mealworm butter, and the other side is just regular butter. All that’s said really is “this is insect butter.” There are two choices, so no one is forcing you to do anything, but it’s there at your table, and you know some percentage of people will be curious enough to try it, and it tastes just fine, a few wormy bits in it but nothing that detracts from the pleasure of the bread. So that might get people in there slowly as well. One idea that we like is just getting one of these little things to stick next to your microwave in your kitchen, a locustarium or something, that’s only so big but would generate a few insects on a regular basis.

If you’re on Port Meadow and a little ladybug lands on the head of your beer at the pub, do you throw it away? Of course not. I just pick the ladybug out and continue drinking.

Most of the psychology of bug eating was done by Paul Rozin [Professor of Psychology at the University of Pennsylvania] in the 1980s looking at disgust. He always uses a cockroach as his insect of choice. The classic experiment is: here’s a glass of apple juice and a glass of orange juice, let’s drop a little sterilized cockroach into one of those drinks, take it out, and now how much do you want to drink it? And everyone says, “No, of course not, I don’t want to.” So there’s this idea of contamination, even from a sterile insect, whereas you know if you’re on Port Meadow [next to the Thames River in Oxford] and a little ladybug lands on the head of your beer at the pub, do you throw it away? Of course not. I just pick the ladybug out and continue drinking.

So there’s no idea of contamination there – there are some insects that are more closely associated with disgust and contamination, and others you don’t care about. Making that distinction between different classes of insects – how many is it? A million insect types out there? – will also be important. That’s why, with the chef in the lab whose father is a beekeeper – sure, bees are endangered, but all the baby male bees, no one knows what to do with them, and they don’t want to get disposed of – so he brings them in and makes ganache and ice cream out of them, and we serve that and it’s very tasty. That’s kind of saying, okay, you already eat honey don’t you? That’s a bee product, an insect product. You already eat pollen and royal jelly, so already you’ve got 3 or 4 insect-based products that you’re quite happy to eat, so maybe picking on bees is the best. We’ve already got the perfect name – the Killer Bee ice cream. And of course we’re thinking about the packaging, what should it come in as well. You’re already there eating insects and things contaminated by bees, and so the ice cream should be an easy way in, and then from there, broaden it out. One of the juices that we have to break down stuff in our gut is most likely there to break down insect matter. It could have another purpose, but its distribution across populations from the poles to insect-rich landscapes suggest in fact, somewhere in our past, we were eating bugs.

I think it’s great, this bugs by stealth kind of approach. It’s funny, if you showed me a picture of, say, a shrimp and a grasshopper side-by-side, it’s a tough competition for the ugliest bug there, but everyone is fine with eating stuff out of the sea… Now, now, I’m not sure, but there must be a history book written somewhere 200 years ago, and no one would eat those insects of the sea floor. You couldn’t give shellfish away unless you were feeding the poor or when people were starving, nothing else. And that’s completely changed! Now they’ve become a highly desirable foodstuff. So, what changed, and how did that change in attitude take place?

Eating chocolate seems to make other people look more attractive.

Going back to the kind of multi-sensory eating experience, do the people that you eat with have any effect on how delicious you perceive your food to be or vice versa, does great food make you appreciate your company even more? Could you hijack a first date by- All sorts of devious means! [Laughs] We’ve found that pleasant fragrances make people look more attractive. Some of my students in Germany have been doing experiments getting people to eat chocolate and then rate attractiveness, so eating chocolate seems to make other people look more attractive. Whether it’s the aroma of chocolate or what we haven’t figured it out yet, but something is in there, so it could work that way. Certainly the people you’re with affect your mood and your mood affects how much you enjoy your food. There are some scary numbers about the number of people at your table – really a strong correlation between the number of people at your table and how much you end up eating. So something like with 7 other people at the table, you double your food intake.

There’s also the nice behavioral economics work insisting that those who order later in the sequence like their food less. Asking “what will you have?” and then “well, you’ve already ordered it, so I’ve got to order something else,” and that kind of translates into a slight reduction in liking. And then there’s all the studies in rats where preferences for food can be picked up from the breath of other rats – I’m not sure if we do that, but maybe. So it does go both ways, the company affects your mood, mood affects perception of food. The more people, the more you eat, but the less you like it, because you order later on average. And then what you eat – it could be the chocolate that makes people more attractive, or, what I always used to do was cook very spicy food, and that leads to, well, pupil dilation and sweating, which might be confused for, you know… [laughs] the source of that arousal might be misattributed. But it worked. Those sort of things like if you’re on a rope bridge and it looks like it’s going to fall, and if you’re asked for a date up there by somebody, you’re more likely to say yes and that they look more attractive than if the same person asks you on dry land.

Is there one thing that you find is perhaps of greater importance – a color or shape or something that really seems to stand out in terms of the whole sensory experience? Definitely not taste, because there’s not much of the brain given over to taste – sweet, sour, bitter, salty. That’s the starting point for it all, but in fact, not at all interesting, by and large. If you lose your tongue, or lose your taste buds, you wouldn’t really notice a difference.

It probably has to be vision in the sense that you always see foods before you taste them, and most of your expectations about food come from what it looks like and how it’s presented. So that’s probably the biggest one, and those expectations then anchor the experience that comes thereafter. But maybe sound is the one that’s least thought about, or at least not until recently, and it’s the easiest thing to change. If I said I could change the light bulbs in here and you’d eat less breakfast but be no less satiated, you might say, okay, but I can’t really be bothered to change the light bulbs or paint the walls. But if I said it was something as simple as music, that’s much easier for someone to change. Sound is never going to reach the heights of what vision can do to you, but, it’s been neglected for so long and it’s so simple to change and modify.

Interview conducted by Meghan Rossi and Drew Duglan and transcribed by Meghan Rossi. Interview has been edited for brevity and clarity.