The yuck factor: How scientific research into revulsion is shaping our supermarkets

The yuck factor: How scientific research into revulsion is shaping our supermarkets
Toenail clippings, creepy-crawlies, rotting food – scientists devote their research to the most disgusting things. But there are serious lessons to be learnt about revulsion.
By Simon Usborne
Published: 11 July 2007

You watch as a dead but sterilised cockroach is dipped for two seconds into a freshly poured glass of orange juice. Then you're offered a sip. Do you raise the glass to your lips and take a gulp – after all, there's nothing wrong with the juice – or do you turn up your nose in disgust and push it away?
That was the choice given to a group of scientists at a lecture by Professor Paul Rozin, a specialist in the psychology of disgust. Everyone rejected the juice, and if the very thought of it causes you emit a "yuck", Professor Rozin is proving his theory – the concept of touch-transference.
Rozin's research says that if something we perceive to be dirty or disgusting (such as a cockroach) touches something harmless (such as orange juice), in our minds the latter becomes "contaminated", even if the rational side of our brain knows there is nothing physically wrong with it.
Among the participants in Rozin's experiment were Andrea Morales, an assistant professor of marketing at Arizona State University, and Gavan Fitzsimons, a psychology and marketing professor at Duke University, North Carolina. The scientists were fascinated by Rozin's work and began to wonder how disgust could shape consumer behaviour.
An article Morales and Fitzsimons published in the Journal of Marketing Research last month suggests that as we push our trolleys around the supermarket, a lot more goes through our minds than how to nab the best bargain. According to their research, "disgusting" items on the supermarket shelf – such as lard, nappies, athlete's foot cream – can have a remarkable effect on the way we view other products that come into contact with them. "It's predominately a non-conscious effect," says Morales. "It sounds ridiculous to not want a packaged product that was touching another packaged product, but it's real."
So what separates a disgusting product from a desirable one? To find out, Morales drew up a list of the 200 top-selling food and non-food items from an average supermarket. She then asked volunteers to evaluate them using a 10-point scale of disgust. Scores above five indicated a moderate level of repulsion. These products included sanitary products and stomach medicines (" Just the word 'gastrointestinal' was enough to elicit a negative response," says Morales) as well as cat litter, dog food, and rubbish bags. Cigarettes topped the disgust chart.
"We didn't ask them to explain their choices," says Morales. " But in most cases you can kind of understand them." But there was one decision Morales couldn't explain. "There was an interesting reaction to mayonnaise," she says. "Half the population doesn't find it at all disgusting but the other half is grossed out by it."
With her "disgusting" trolley filled, Morales took a second basket of more appealing items such as biscuits and rice cakes, and arranged the products on a supermarket shelf for a number of tests. In all cases the items remained sealed, removing any risk of actual contact, much less contamination. The only variable was that in some instances the desirable products touched the disgusting ones, while in others they were separated by a few inches.
Volunteers were then asked to look at the shelf, but were not told why. After a few minutes they were asked questions such as "how much would you pay for this item?", or "how appealing do you find this item?" .
"The results were incredibly strong," says Morales. "We always found that in the touching conditions, ratings of the cookies or rice cakes would always be lower than when they were not touching." Even more surprising were the results of a second test in which participants were asked to evaluate the products more than an hour after viewing them, still not realising what the experiment was about. "The effect was the same," says Morales. "When my students hear the theory they always say it wouldn't happen to them, but they're amazed when they react in the same way."
British psychologist Dr David Lewis, an expert on the science of the supermarket, or "trolleyology", as it has become known, says these kinds of responses serve an important evolutionary function: "It seems irrational not to eat biscuits because they're on a shelf next to some nappies when both are wrapped up in layers of cellophane, but these inbuilt disgusts are designed to prevent us doing things which could harm us." Morales adds: "There are plenty of cases where the effect is rational – if a cockroach touches orange juice we know we shouldn't drink it – but we seem to have generalised what is rational to include cases where it simply doesn't apply."
So are supermarkets aware of product contagion? "They are generally aware of everything," says Dr Lewis, who has advised some of the UK's top retailers. "These aren't shops but machines designed to sell, and you'd be amazed how much thought goes into product placement."
But Morales suggests shop managers could do more. "Store layout is becoming more important as supermarkets start clustering products that wouldn't normally appear together." Morales points to "baby" aisles as a prime example where "disgusting" products such as nappies or wipes might appear next to baby food or toys. "If they separated them they'd sell more," she says.
Morales also advises supermarkets to let shoppers keep products apart away from the shelf. "They could put more separators in trolleys to keep things from coming into contact with each other. Or an extra bag to put diarrhoea medicine in."
Measures like this might seem unnecessary but Morales says they could affect profits. "Usually it takes a while for research like this to trickle down to managerial practice," she says. "But it's only a matter of time before they say, 'Wait – we should apply this.'"
This isn't the first time Morales has studied the psychology of disgust on the shop floor. She achieved similar results in earlier research into " consumer contamination". When picked up this newspaper, did you take the second one in the pile? If you did, you're not alone. "It's the same mechanism," says Morales. "We feel disgusted knowing someone else may have been in contact with the products we want to buy so we devalue these 'contaminated' products."
However irrational, this response serves the same evolutionary function: to prevent the spread of disease. If we know or assume an item has already been touched, we assume the "contaminator" has had a negative effect on it that could pose a risk. But in one experiment, where Morales hired models to handle T-shirts in a mock-up of a clothes shop, the opposite is also true.
It's no mystery that attractive sales assistants help sell more clothes, but Morales' research shows it's not as simple as that. In her experiment, shoppers who had seen someone attractive of the opposite sex touching a T-shirt were more likely to buy it. "It isn't enough for an attractive person to like a T-shirt – they have to touch it and 'transfer' their attractiveness on to it."
So what's next for Morales and Fitzsimons? A new study will take them back to the supermarket and to how we behave not when we see a disgusting product, but when we have to buy one. Preliminary research suggests that adding something nasty to our shopping list can affect what else we buy and even force us into making unplanned purchases.
"If we go in for antifungal foot cream, we might then subconsciously choose to get some soap to fight the feeling of disgust we have. We might also put off buying things like fruit and veg."
So could that spell the end of the in-store chemist and pet food aisle? " At f irst we thought the effect might cut down the size of the basket, so maybe that would have had implications on the kinds of products stores stock, but we found that it changes the types of products, not the quantity. If supermarkets sell more soap, well that's probably OK with them."

The anatomy of disgust

* International surveys have revealed universal sources of disgust, including bodily secretions, wounds, corpses, toenail clippings, decaying food, creepy crawlies, and people who are ill.

* Most scientists believe we are genetically hardwired to be disgusted by things that could make us ill, and that a "disgust gene" arose through the process of natural selection.

* Disgust grows as we learn what might pose a threat; babies presented with fake faeces find them fascinating, while older children and adults are repulsed.

* Studies have revealed culture-specific disgusts, including dog meat in the UK, food cooked by menstruating women in India, and fat people in the Netherlands.

* The way we express disgust is universal; we use the same facial expression, triggered by the anterior insular cortex part of the brain, and even the same word – "yuck".

Hard sell: the things that get left on the shelf

Baby food and nappies

It might seem logical to group baby products on the same supermarket aisle, but research suggests items that come into contact with nappies, with all their connotations, become contaminated in our minds.

Mayonnaise and soup

Researchers were surprised when many subjects singled out mayonnaise as a " disgusting" product which, when shelved next to more palatable products such as soup, might put customers off buying.

Feminine hygiene products and paper towels

According to research, tampons and face towels should never share shelf space. Psychologists say the "yucky" associations of hygiene products taint items that we choose for their cleansing qualities.

Diarrhoea medicine and aspirin

Anything with the word "diarrhoea" or "gastrointestinal" is enough to turn the stomach, and, on a subconscious level, could taint products such as aspirin, which ideally are seen by consumers to have cleansing connotations.