The sensation of taste includes five established basic tastes: sweetness, sourness, saltiness, bitterness, and umami. Scientific experiments have demonstrated that these five tastes exist and are distinct from one another.
Taste buds are able to distinguish between different tastes through detecting interaction with different molecules or ions. Sweet, savory, and bitter tastes are triggered by the binding of molecules to G protein-coupled receptors on the cell membranes of taste buds. Saltiness and sourness are perceived when alkali metal or hydrogen ions enter taste buds, respectively.
In this video, neuroscientist Camilla Arndal Andersen takes us into the lab where she studies people’s sense of taste via brain scans. She reveals surprising insights about the way our brains subconsciously experience food – and shows how this data could help us eat healthier without sacrificing taste.
So I had this very interesting experience five years ago. You know, me and my husband, we were out grocery shopping, as we do every other day, but this time, we found this fancy, you know, I’m talking fair-trade, I’m talking organic, I’m talking Kenyan, single-origin coffee that we splurged and got.
And that was when the problem started already. You know, my husband, he deemed this coffee blend superior to our regular and much cheaper coffee, which made me imagine a life based solely on fancy coffee and I saw our household budget explode.
And worse … I also feared that this investment would be in vain. That we wouldn’t be able to notice this difference after all. Unfortunately, especially for my husband, he had momentarily forgotten that he’s married to a neuroscientist with a specialty in food science.
Alright? So without further ado, I mean, I just put him to the test. I set up an experiment where I first blindfolded my husband.
Then I brewed the two types of coffee and I told him that I would serve them to him one at a time. Now, with clear certainty, my husband, he described the first cup of coffee as more raw and bitter. You know, a coffee that would be ideal for the mornings with the sole purpose of terrorizing the body awake by its alarming taste.
The second cup of coffee, on the other hand, was both fruity and delightful. You know, coffee that one can enjoy in the evening and relax. Little did my husband know, however, that I hadn’t actually given him the two types of coffee. I had given him the exact same cup of coffee twice.
How We Sense Food
And obviously, it wasn’t this one cup of coffee that had suddenly gone from horrible to fantastic. No, this taste difference was a product of my husband’s own mind. Of his bias in favor of the fancy coffee that made him experience taste differences that just weren’t there.
Alright, so, having saved our household budget, and finishing on a very good laugh, me especially, I then started wondering just how we could have received two such different responses from a single cup of coffee. Why would my husband make such a bold statement at the risk of being publicly mocked for the rest of his life?
The striking answer is that I think you would have done the same. And that’s the biggest challenge in my field of science, assessing what’s reality behind these answers that we receive. Because how are we going to make food tastier if we cannot rely on what people actually say they like?
To understand, let’s first have a look at how we actually sense food.
When I drink a cup of coffee, I detect this cup of coffee by receptors on my body, information which is then turned into activated neurons in my brain. Wavelengths of light are converted to colors.
Molecules in the liquid are detected by receptors in my mouth, and categorized as one of five basic tastes. That’s salty, sour, bitter, sweet and umami. Molecules in the air are detected by receptors in my nose and converted to odors. And ditto for touch, for temperature, for sound and more.
All this information is detected by my receptors and converted into signals between neurons in my brain. Information which is then woven together and integrated, so that my brain recognizes that yes, I just had a cup of coffee, and yes, I liked it. And only then, after all this neuron heavy lifting, do we consciously experience this cup of coffee.
And this is now where we have a very common misconception.
People tend to think that what we experience consciously must then be an absolute true reflection of reality. But as you just heard, there are many stages of neural interpretation in between the physical item and the conscious experience of it. Which means that sometimes, this conscious experience is not really reflecting that reality at all. Like what happened to my husband.
That’s because some physical stimuli may just be so weak that they just can’t break that barrier to enter our conscious mind, while the information that does may get twisted on its way there by our hidden biases. And people, they have a lot of biases.
Biases
Yes, if you’re sitting there right now, thinking … you could probably have done better than my husband, you could probably have assessed those coffees correctly, then you’re actually suffering from a bias. A bias called the bias blind spot. Our tendency to see ourselves as less biased than other people.
And yeah, we can even be biased about the biases that we’re biased about. Not trying to make this any easier.
A bias that we know in the food industry is the courtesy bias. This is a bias where we give an opinion which is considered socially acceptable, but it’s certainly not our own opinion, right? And I’m challenged by this as a food researcher, because when people say they like my new sugar-reduced milkshake, do they now?
Or are they saying they like it because they know I’m listening and they want to please me? Or maybe they just to seem fit and healthy in my ears.
I wouldn’t know. But worse, they wouldn’t even know themselves.
Even trained food assessors, and that’s people who have been explicitly taught to disentangle the sense of smell and the sense of taste, may still be biased to evaluate products sweeter if they contain vanilla.
Why? Well, it’s certainly not because vanilla actually tastes sweet. It’s because even these professionals are human, and have eaten lot of desserts, like us, and have therefore learned to associate sweetness and vanilla.
So taste and smell and other sensory information is inextricably entangled in our conscious mind. So on one hand, we can actually use this. We can use these conscious experiences, use this data, exploit it by adding vanilla instead of sugar to sweeten our products. But on the other hand, with these conscious evaluations, I still wouldn’t know whether people actually liked that sugar-reduced milkshake.
Brain Direct
So how do we get around this problem? How do we actually assess what’s reality behind these conscious food evaluations? The key is to remove the barrier of the conscious mind and instead target the information in the brain directly.
And it turns out our brain holds a lot of fascinating secrets. Our brain constantly receives sensory information from our entire body, most of which we don’t even become aware of, like the taste information that I constantly receive from my gastrointestinal tract.
And my brain will also act on all this sensory information. It will alter my behavior without my knowledge, and it can increase the diameter of my pupils if I experience something I really like. And increase my sweat production ever so slightly if that emotion was intense. And with brain scans, we can now assess this information in the brain.
Specifically, I have used a brain-scanning technique called electroencephalography, or “EEG” in short, which involves wearing a cap studded with electrodes, 128 in my case. Each electrode then measures the electrical activity of the brain with precision down to the millisecond.
The problem is, however, it’s not just the brain that’s electrically active, it’s also the rest of the body as well as the environment that contains a lot of electrical activity all the time. To do my research, I therefore need to minimize all this noise. So I ask my participants to do a number of things here.
First off, I ask them to rest their head in a chin rest, to avoid too much muscle movement. I also ask them to, meanwhile, stare at the center of a computer monitor to avoid too much eye movements and eye blinks. And I can’t even have swallowing, so I ask my participants to stick the tongue out of their mouth over a glass bowl, and then I constantly let taste stimuli onto the tongue, which then drip off into this bowl.
And then, just to complete this wonderful picture, I also provide my participants with a bib, available in either pink or blue, as they please.
Looks like a normal eating experience, right?
No, obviously not. And worse, I can’t even control what my participants are thinking about, so I need to repeat this taste procedure multiple times. Maybe the first time, they’re thinking about the free lunch that I provide for participating, or maybe the second time, they’re thinking about Christmas coming up and what to get for Mom this year, you know.
But common for each response is the response to the taste. So I repeat this taste procedure multiple times. Sixty, in fact. And then I average the responses, because responses unrelated to taste will average out.
And using this method, we and other labs, have investigated how long a time it takes from “food lands on our tongue” until our brain has figured out which taste it’s experiencing. Turns out this occurs within the first already 100 milliseconds, that’s about half a second before we even become aware of it.
And next up, we also investigated the taste difference between sugar and artificial sweeteners that in our setup taste extremely similar. In fact, they tasted so similar that half my participants could only barely tell the taste apart, while the other half simply couldn’t. But amazingly, if we looked across the entire group of participants, we saw that their brains definitely could tell the taste apart.
Creating Tastier Foods
So with EEG and other brain-scanning devices and other physiological measures – sweat and pupil size – we have new gateways to our brain. Gateways that will help us remove the barrier of the conscious mind to see through the biases of people and possibly even capture subconscious taste differences.
And that’s because we can now measure people’s very first response to food before they’ve become conscious of it, and before they’ve started rationalizing why they like it or not.
We can measure people’s facial expressions, we can measure where they’re looking, we can measure their sweat response, we can measure their brain response. And with all these measures, we are going to be able to create tastier foods, because we can measure whether people actually like that sugar-reduced milkshake.
And we can create healthier foods without compromising taste, because we can measure the response to different sweeteners and find the sweetener that gives the response that’s more similar to the response from sugar.
And furthermore, we can just help create healthier foods, because we can help understand how we actually sense food in the first place. Which we know surprisingly little about.
For example, we know that there are those five basic tastes, but we strongly suspect that there are more, and in fact, using our EEG setup, we found evidence that fat, besides being sensed by its texture and smell, is also tasted. Meaning that fat could be this new sixth basic taste.
And if we figure out how our brain recognizes fat and sugar, and I’m just dreaming here, but could we then one day create a milkshake with zero calories that tastes just like the real deal? Or maybe we figure out that we can’t, because we subconsciously detect calories via our receptors in our gastrointestinal tract. The future will show.
Our conscious experience of food is just the tip of the iceberg of our total sensation of food. And by studying this total sensation, conscious and subconscious alike, I truly believe that we can make tastier and healthier foods for all.
Thank you.
This video and transcript is courtesy of Ted Talks, republished via Creative Commons CC BY-NC-ND 4.0.