Perception vs. reality is a venerable versus. From prisoners in Plato’s cave mistaking shadows for reality, to studies about the unreliability of eyewitnesses, the difference between what is and what we perceive has been a problem for thousands of years.
When it comes to eating and drinking, most of us generally assume that what we taste and smell is what’s there in the food. In fact it’s not. Fortunately, the categorical accuracy of what is or isn’t there is less important at the table than in the witness box. What actually matters at the table is perception. Perception is king when we’re eating and enjoying. It is its own reality.
FLAVOR IS IN THE BRAIN, NOT IN FOODS
There’s a simple fact that underlies the general discrepancy between perception and reality—why it is that we can’t trust our faculties of perception to give us a full and straightforward account of what’s around us: our brains and our senses are selective about what they notice about reality. They’re error-prone, and each of us makes his or her own unconscious selections and errors. Each of us has perceptions that don’t necessarily correspond to someone else’s. These days, neuroscientists are telling us that flavor is all in the brain. Flavor is a perception, an experience that’s constructed in the brain. Food is made up of molecules, and molecules by themselves don’t have any sensory qualities. Our experience of food is sensory: there’s taste and smell and pungency, texture and temperature. The chemical and physical materials that generate these sensations in us do not, by themselves, have any of those qualities.
So the quality of saltiness is something that is the result of sensors in our tongue telling our brain that there are sodium and chloride ions in whatever we just put in our mouth. Our brain turns that into a sensation of saltiness. Yes, chemically, the food has salt in it—but the taste and experience of salt is a construction of our brain and the sensors that feed into it.
Moreover, each of us has a different set of sensors and a different brain. This is partly a matter of genetics. There are a half dozen taste receptors and a few hundred different smell receptors; no one gets a complete set, and everyone gets a different set. There can be a tenfold difference between one person and another in the number of taste buds on their tongues. And we all have different databases of experience to which the brain is always referring to make sense of what’s going on in the moment.
The chili pepper offers another twist to the tangled nature of perception. You put something in your mouth and it is a certain objective temperature, X number of degrees Fahrenheit, and your body registers that particular temperature as being cold or warm or hot. Then you eat a chili pepper, and you eat exactly the same food at exactly the same temperature, and it seems hotter. Chili peppers contain capsaicin, a chemical that messes with the heat sensors on your tongue; it can shift your sensors’ response by ten or fifteen degrees. Temperature is an objective, measurable thing, but our perception of temperature is very much dependent on our tongue, our brain, and whatever we may have exposed our temperature sensors to beforehand.
Smell is usually the dominant sense in the experience of flavor. The smell receptors in the upper nose report on some of the molecules that escape from food into the air, but when the brain turns that report into a smell perception, it edits it, taking into account past reports in its database of smell experiences. It’s not a pure account of what smell molecules are present. Initially the brain is interested in a smell to evaluate what it might mean for survival. Is this stuff going to sustain me or kill me? Certain smells go with food, others go with danger, and so on. Your brain makes a prediction, and generates signals of attraction or disgust from the database it has accumulated.
When you think about how we describe tastes, we have abstract words for sweet and sour and bitter. But if you talk about aroma in a wine, it’s going to be a leather saddle or a raspberry. We name smells by the materials we’ve experienced those molecules in before. The moment you smell something and recognize it, you’re relying on past experiences of reality. Those experiences in turn influence what you experience in the moment.
So flavor’s all in the brain. But cooks create flavor by what they do with foods, even if in reality we’re all experiencing things differently. They know that if you add salt to a food, you’re going to increase everyone’s perception of saltiness. Those things are commonsensical. But it can be useful for cooks to know things that aren’t so obvious.
One is that some people are hypersensitive to salt, and others are hyposensitive. This isn’t simply a matter of preference; it’s the very different intensity experienced by different people from the same food. It’s good for any cook to compare notes with others and know where his or her taste buds are on that spectrum. Salting only to your own taste can limit your food’s appeal.
Another thing worth knowing about flavor perception is mixture suppression, which is how tastes and smells tend to dampen our perception of the other tastes and smells they are mixed with.
If you give someone a salt solution and ask them how salty it is, they might rate it a seven on a scale of ten. But if you add a little bit of sugar and ask them to rate the same solution again, they’ll say five. The elements of a mixture tend to suppress each other.
Plainly, this means that if you really want people to experience something in particular, you actually don’t want to have a lot of other stuff going on at the same time. If you have a very simple combination of tastes or smells, then you perceive those tastes and smells clearly. If you complicate the situation by adding more tastes or more smells, then your perception of the prior, already-there tastes and smells is diminished because now you’ve got something else to pay attention to. If you want to emphasize tartness, then you don’t add salt or sugar, except if you want to balance it, in which case you are intentionally dampening down its perception.
You can think of mixture suppression as working a bit like an audio equalizer. With just one or two flavors, you have prominent peaks that are jumping way up above everything else. If you want to keep everything below the red line and balance and even things out, then you add a couple more components.
One notable exception to the phenomenon of mixture suppression is umami—glutamate and its coconspirators tend somehow to increase our sensitivity to salt. So if you add glutamate to something that’s salty, it’ll tend to taste saltier, not less salty. Now, we only have a half dozen tastes that we know about, but we have thousands of different smells we recognize, so mixture suppression becomes more complicated with smell because it is much more various and variable.
There was an interesting experiment done by Dr. Noam Sobel at the Weizmann Institute of Science in Israel a few years ago that showed that if you mix enough different smells that are about equal in their intensity, once you have about thirty different odorants, you reach what he calls “olfactory white.” It’s kind of like white noise; you can’t really pick out anything in particular. That’s useful for a cook to keep in mind when composing dishes. Sometimes you just want to put all kinds of ingredients in there because they’re cool, or they’re interesting, or delicious in other contexts. But after a certain point you’re just creating white noise.
There’s also a limit to the number of smells that someone can actually distinguish and appreciate in a dish. Sensory psychologists have demonstrated that if you give people one familiar smell and then a second equally strong smell and a third and so on, the number at which they max out being able to identify the different smells is around four. Four!
Of course this was an academic exercise. When we’re having wine or food, no one’s engineered the experience to make sure every smell has an equal chance of being detected or not, and we take repeated sips and bites. Some flavors are stronger and some are weaker, some aromas fade while others persist. If you smell something that’s really strong you may adapt to it, so the next sip or bite highlights something different. Still, when it comes to building the flavor of a dish, more isn’t always more.
Our experience of flavor is influenced by other senses, not just taste and smell. Touch is how we judge texture, and vision and hearing also play important roles. Flavor is also affected by cognitive influences, by memories and thoughts and ideas about the particular foods that are in front of you.
Sometimes these non-gustatory influences are taken as evidence that our perceptions of food and drink are unreliable. Even wine experts describe the flavor of a white wine differently when a touch of red food coloring is added to it, and people have been known to like a wine more if it’s described as expensive. Yes, our perceptions are easily manipulated. But the other way to look at it is, if you’re aware of all these other influences on your perception, as a cook or a restaurateur, you can use them to your advantage. Not to deceive or embarrass, but to intensify and enhance and emphasize. You can consider all the aspects of presentation and setting that influence the way people perceive what you actually put into the food itself.
Dr. Charles Spence is a sensory psychologist at Oxford who studies and writes extensively about these matters, which are called “crossmodal associations.” He published a book in 2014 that I think a lot of cooks would be interested in, The Perfect Meal: The Multisensory Science of Food and Dining. It’s a summary of the research that’s been done on crossmodal correspondences with flavor: how the color of foods makes a difference to how we perceive them, as does the color of the plate, the shape of the plate, the music or noise in the background, what the menu or the server tells you about the food.
For example, in the early days of modernist cooking, Heston Blumenthal made a savory ice cream with crab at The Fat Duck. He discovered that if it was described as crab ice cream, people didn’t like it much. But when he changed the name to frozen crab bisque—exactly the same recipe—people loved it. That was higher-level thinking at work, affecting the basic perception and pleasure that we take in a food.
Sensory scientists have learned from experiments with brain imaging that if someone reads the word cinnamon on a menu, the parts of the brain that respond to smells light up. You’re not actually eating or even looking at a fleck of cinnamon, but you’re reading and thinking and that’s enough to get your brain to be, in a way, virtually smelling cinnamon.
Dr. Spence’s book is filled with dozens of examples of this kind. He and other researchers have found that in a setting where there are sounds that are not related at all to what you’re eating, loud rock music or something like that, eaters tend to be less sensitive to the flavors in foods. They rate the foods that they’re eating as being less intense and satisfying than they do if it’s quiet, probably in part because they’re less distracted and can actually sense more.
But sound can work in both directions. In a collaboration with Heston Blumen thal, Spence confirmed Blumenthal’s hunch that if you supply noises that are somehow congruent to the experience of eating what you’re eating, it has an enhancing effect on the experience rather than a distracting effect. That led to Blumenthal developing his dish “The Sound of the Sea,” which looks like a line of sea-foam on sand, has real sand visible underneath a glass plate, and is accompanied by a conch shell with earbuds through which you hear waves and seagulls.
Some establishments will be more interested in enhancing flavor perception, while others will be more interested in distracting from it. Work by Dr. Spence and others has shown that the noisier a restaurant or bar is, the less intense and less pleasant people perceive flavors to be—and the faster and more they tend to drink. Since a similar effect is seen in lab animals, it’s been proposed that this effect is partly a stress response! So if what you’re trying to do is sell drinks, it’s a great idea to have loud music or lots of hard, noise–reflecting surfaces. And if you’re like me and don’t like loud restaurants, you can know that it’s not just a matter of being unable to hear your companions. You’re getting less enjoyment from the food, and paying for the privilege of subliminal stress.
PERCEPTION AT SECOND HAND
Knowing a bit about the realities of flavor perception can help any of us get more out of our perceptions. Because flavor is an experience formed in the brain, we can influence it by taking advantage of what some sensory psychologists have referred to as “perception at second hand.” We can choose to open our brain to what other people experience or know—a story from a wine expert who chose the wine, or cheesemonger who chose the cheese, or impressions from our friends around the table. Our experience of that food or drink can be enriched by becoming aware of other dimensions that we might otherwise not have noticed.
We can also choose to make an awareness of how we perceive flavor part of the experience. That can encourage us to pay more attention to the details, to work a little harder to pin down qualities and echoes and resonances and personal meanings.
I realize that it probably sounds paralyzingly overwhelming and crazy to talk like this about something as basic as tasting food! But what it boils down to is: if you’re aware of how your perception of flavor can be shaped by all these different factors, then your inner reality can be as rich and complicated as you want it to be. It’s up to you to construct it.