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← What happens in your brain when you taste food

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Showing Revision 8 created 10/03/2019 by Oliver Friedman.

  1. So I had this very interesting experience
  2. five years ago.
  3. You know, me and my husband,
    we were out grocery shopping,
  4. as we do every other day,
  5. but this time, we found this fancy,
  6. you know, I'm talking fair-trade,
    I'm talking organic,
  7. I'm talking Kenyan, single-origin coffee
  8. that we splurged and got.
  9. And that was when the problem
    started already.

  10. You know, my husband,
    he deemed this coffee blend superior
  11. to our regular and much cheaper coffee,
  12. which made me imagine a life
    based solely on fancy coffee
  13. and I saw our household budget explode.
  14. (Laughter)

  15. And worse ...

  16. I also feared that this investment
    would be in vain.
  17. That we wouldn't be able to notice
    this difference after all.
  18. Unfortunately, especially for my husband,
  19. he had momentarily forgotten
    that he's married to a neuroscientist
  20. with a specialty in food science.
  21. (Laughter)

  22. Alright?

  23. So without further ado,
  24. I mean, I just put him to the test.
  25. I set up an experiment
  26. where I first blindfolded my husband.
  27. (Laughter)

  28. Then I brewed the two types of coffee

  29. and I told him that
    I would serve them to him
  30. one at a time.
  31. Now, with clear certainty,
  32. my husband, he described
    the first cup of coffee
  33. as more raw and bitter.
  34. You know, a coffee
    that would be ideal for the mornings
  35. with the sole purpose of terrorizing
    the body awake by its alarming taste.
  36. (Laughter)

  37. The second cup of coffee,
    on the other hand,

  38. was both fruity and delightful.
  39. You know, coffee that one
    can enjoy in the evening and relax.
  40. Little did my husband know, however,
  41. that I hadn't actually given him
    the two types of coffee.
  42. I had given him the exact same
    cup of coffee twice.
  43. (Laughter)

  44. And obviously, it wasn't
    this one cup of coffee

  45. that had suddenly gone
    from horrible to fantastic.
  46. No, this taste difference
    was a product of my husband's own mind.
  47. Of his bias in favor of the fancy coffee
  48. that made him experience taste differences
    that just weren't there.
  49. Alright, so, having saved
    our household budget,
  50. and finishing on a very good laugh,
  51. me especially --
  52. (Laughter)

  53. I then started wondering
    just how we could have received

  54. two such different responses
    from a single cup of coffee.
  55. Why would my husband
    make such a bold statement
  56. at the risk of being publicly mocked
    for the rest of his life?
  57. (Laughter)

  58. The striking answer is
    that I think you would have done the same.

  59. And that's the biggest challenge
    in my field of science,
  60. assessing what's reality
    behind these answers
  61. that we receive.
  62. Because how are we
    going to make food tastier
  63. if we cannot rely on what people
    actually say they like?
  64. To understand, let's first have a look
    at how we actually sense food.

  65. When I drink a cup of coffee,
  66. I detect this cup of coffee
    by receptors on my body,
  67. information which is then turned
    into activated neurons in my brain.
  68. Wavelengths of light
    are converted to colors.
  69. Molecules in the liquid
    are detected by receptors in my mouth,
  70. and categorized as one
    of five basic tastes.
  71. That's salty, sour,
    bitter, sweet and umami.
  72. Molecules in the air
    are detected by receptors in my nose
  73. and converted to odors.
  74. And ditto for touch, for temperature,
    for sound and more.
  75. All this information is detected
    by my receptors
  76. and converted into signals
    between neurons in my brain.
  77. Information which is then
    woven together and integrated,
  78. so that my brain recognizes
  79. that yes, I just had a cup of coffee,
    and yes, I liked it.
  80. And only then,
  81. after all this neuron heavy lifting,
  82. do we consciously experience
    this cup of coffee.
  83. And this is now where we have
    a very common misconception.
  84. People tend to think
    that what we experience consciously

  85. must then be an absolute
    true reflection of reality.
  86. But as you just heard,
  87. there are many stages
    of neural interpretation
  88. in between the physical item
    and the conscious experience of it.
  89. Which means that sometimes,
  90. this conscious experience is not really
    reflecting that reality at all.
  91. Like what happened to my husband.
  92. That's because some physical stimuli
    may just be so weak
  93. that they just can't break that barrier
    to enter our conscious mind,
  94. while the information that does
  95. may get twisted on its way there
    by our hidden biases.
  96. And people, they have a lot of biases.
  97. Yes, if you're sitting there
    right now, thinking ...

  98. you could probably have done
    better than my husband,
  99. you could probably have assessed
    those coffees correctly,
  100. then you're actually
    suffering from a bias.
  101. A bias called the bias blind spot.
  102. Our tendency to see ourselves
    as less biased than other people.
  103. (Laughter)

  104. And yeah, we can even be biased

  105. about the biases that we're biased about.
  106. (Laughter)

  107. Not trying to make this any easier.

  108. A bias that we know in the food industry
    is the courtesy bias.

  109. This is a bias where we give an opinion
  110. which is considered socially acceptable,
  111. but it's certainly not
    our own opinion, right?
  112. And I'm challenged by this
    as a food researcher,
  113. because when people say they like
    my new sugar-reduced milkshake,
  114. do they now?
  115. (Laughter)

  116. Or are they saying they like it

  117. because they know I'm listening
    and they want to please me?
  118. Or maybe they just to seem
    fit and healthy in my ears.
  119. I wouldn't know.
  120. But worse, they wouldn't
    even know themselves.
  121. Even trained food assessors,
  122. and that's people who have been
    explicitly taught
  123. to disentangle the sense of smell
    and the sense of taste,
  124. may still be biased
    to evaluate products sweeter
  125. if they contain vanilla.
  126. Why?
  127. Well, it's certainly not
    because vanilla actually tastes sweet.
  128. It's because even these
    professionals are human,
  129. and have eaten lot of desserts, like us,
  130. and have therefore learned to associate
    sweetness and vanilla.
  131. So taste and smell
    and other sensory information

  132. is inextricably entangled
    in our conscious mind.
  133. So on one hand, we can actually use this.
  134. We can use these conscious experiences,
  135. use this data, exploit it
    by adding vanilla instead of sugar
  136. to sweeten our products.
  137. But on the other hand,
  138. with these conscious evaluations,
  139. I still wouldn't know
  140. whether people actually liked
    that sugar-reduced milkshake.
  141. So how do we get around this problem?

  142. How do we actually assess what's reality
  143. behind these conscious food evaluations?
  144. The key is to remove the barrier
    of the conscious mind
  145. and instead target the information
    in the brain directly.
  146. And it turns out
  147. our brain holds a lot
    of fascinating secrets.
  148. Our brain constantly receives
    sensory information from our entire body,
  149. most of which we don't even
    become aware of,
  150. like the taste information
    that I constantly receive
  151. from my gastrointestinal tract.
  152. And my brain will also act
    on all this sensory information.
  153. It will alter my behavior
    without my knowledge,
  154. and it can increase
    the diameter of my pupils
  155. if I experience something I really like.
  156. And increase my sweat production
    ever so slightly
  157. if that emotion was intense.
  158. And with brain scans,
  159. we can now assess
    this information in the brain.
  160. Specifically, I have used
    a brain-scanning technique

  161. called electroencephalography,
  162. or "EEG" in short,
  163. which involves wearing a cap
    studded with electrodes,
  164. 128 in my case.
  165. Each electrode then measures
    the electrical activity of the brain
  166. with precision down to the millisecond.
  167. The problem is, however,
  168. it's not just the brain
    that's electrically active,
  169. it's also the rest of the body
    as well as the environment
  170. that contains a lot
    of electrical activity all the time.
  171. To do my research,
  172. I therefore need
    to minimize all this noise.
  173. So I ask my participants
    to do a number of things here.
  174. First off,
  175. I ask them to rest their head
    in a chin rest,
  176. to avoid too much muscle movement.
  177. I also ask them to, meanwhile,
    stare at the center of a computer monitor
  178. to avoid too much
    eye movements and eye blinks.
  179. And I can't even have swallowing,
  180. so I ask my participants
    to stick the tongue out of their mouth
  181. over a glass bowl,
  182. and then I constantly let
    taste stimuli onto the tongue,
  183. which then drip off into this bowl.
  184. (Laughter)

  185. And then, just to complete
    this wonderful picture,

  186. I also provide my participants with a bib,
  187. available in either pink
    or blue, as they please.
  188. (Laughter)

  189. Looks like a normal
    eating experience, right?

  190. (Laughter)

  191. No, obviously not.

  192. And worse,
  193. I can't even control
    what my participants are thinking about,
  194. so I need to repeat this taste procedure
  195. multiple times.
  196. Maybe the first time,
    they're thinking about the free lunch
  197. that I provide for participating,
  198. or maybe the second time,
    they're thinking about Christmas coming up
  199. and what to get for Mom
    this year, you know.
  200. But common for each response
    is the response to the taste.
  201. So I repeat this taste
    procedure multiple times.
  202. Sixty, in fact.
  203. And then I average the responses,
  204. because responses unrelated
    to taste will average out.
  205. And using this method,

  206. we and other labs,
  207. have investigated how long a time
    it takes from "food lands on our tongue"
  208. until our brain has figured out
    which taste it's experiencing.
  209. Turns out this occurs within the first
    already 100 milliseconds,
  210. that's about half a second
    before we even become aware of it.
  211. And next up, we also investigated
  212. the taste difference between sugar
    and artificial sweeteners
  213. that in our setup taste extremely similar.
  214. In fact, they tasted so similar
  215. that half my participants
    could only barely tell the taste apart,
  216. while the other half simply couldn't.
  217. But amazingly,
  218. if we looked across
    the entire group of participants,
  219. we saw that their brains
    definitely could tell the taste apart.
  220. So with EEG and other
    brain-scanning devices

  221. and other physiological measures --
  222. sweat and pupil size --
  223. we have new gateways to our brain.
  224. Gateways that will help us
    remove the barrier of the conscious mind
  225. to see through the biases of people
  226. and possibly even capture
    subconscious taste differences.
  227. And that's because we can now measure
    people's very first response to food
  228. before they've become conscious of it,
  229. and before they've started rationalizing
    why they like it or not.
  230. We can measure people's
    facial expressions,
  231. we can measure where they're looking,
  232. we can measure their sweat response,
  233. we can measure their brain response.
  234. And with all these measures,
  235. we are going to be able
    to create tastier foods,
  236. because we can measure
    whether people actually like
  237. that sugar-reduced milkshake.
  238. And we can create healthier foods
    without compromising taste,
  239. because we can measure the response
    to different sweeteners
  240. and find the sweetener that gives
    the response that's more similar
  241. to the response from sugar.
  242. And furthermore, we can just help
    create healthier foods,

  243. because we can help understand
    how we actually sense food
  244. in the first place.
  245. Which we know surprisingly little about.
  246. For example, we know
    that there are those five basic tastes,
  247. but we strongly suspect
    that there are more,
  248. and in fact, using our EEG setup,
    we found evidence that fat,
  249. besides being sensed
    by its texture and smell,
  250. is also tasted.
  251. Meaning that fat could be
    this new sixth basic taste.
  252. And if we figure out
    how our brain recognizes fat and sugar,
  253. and I'm just dreaming here,
  254. but could we then one day
  255. create a milkshake with zero calories
    that tastes just like the real deal?
  256. Or maybe we figure out that we can't,
  257. because we subconsciously detect calories
  258. via our receptors
    in our gastrointestinal tract.
  259. The future will show.
  260. Our conscious experience of food

  261. is just the tip of the iceberg
    of our total sensation of food.
  262. And by studying this total sensation,
  263. conscious and subconscious alike,
  264. I truly believe that we can make
    tastier and healthier foods for all.
  265. Thank you.

  266. (Applause)