Seeing Sound, Tasting Color: Synesthesia

David Eagleman: One of the things I study in my lab is called synesthesia, and it represents a blending of the senses.  So we’ve all heard the anesthesia, which means no feeling.  Synesthesia means joined feeling.  So somebody with synesthesia, they might hear music and it causes them to see colors physically, or they might hear something and it puts a taste in their mouth, physically they’re experiencing that, or they might eat something and it puts a feeling on their fingertips.  The most common forms of synesthesia have to do with over-learned sequences, like letters or numbers or weekdays or months, triggering a color experience.  So somebody might look at the number six and that's red to that synesthete, or they look at the letter J and that's purple.  And it’s an internal experience, it’s automatic, it’s involuntary and it’s unconscious, and to a synesthete it’s just self-evidently true that J is purple.  

It used to be thought this was very rare.  The original estimates were 1 in 20,000, but we now know it’s quite common. It’s probably up to 4 percent of the population has some form of synesthesia.  There are many different forms.  Essentially, any cross-blending of the senses that you can think of, my colleagues and I have found a case somewhere, so we now know it’s very common.  And the reason it’s so interesting to me is because it’s a very good inroad into understanding how different brains can be perceive reality differently, so you’re sitting here, your neighbor is sitting here and you’re both looking at the same thing and yet you’re seeing the world very differently.  

And it turns out synesthesia is heritable, so my lab is pulling the genes for it right now.  And the reason that's so interesting is because it’s what I’m calling perceptual genomics, which is to say how do little genetic changes change the way we perceive reality. And, of course, most synesthetes, historically, have lived their whole lives and they may even die without ever suspecting that they’re seeing reality differently than someone else because we all accept the reality presented to us.  So synesthesia is a really direct way to look at how individual changes can lead to different beliefs about reality.

Directed / Produced by Elizabeth Rodd and Jonathan Fowler

 

Neuroscientist David Eagleman explains how tiny variations in genetics impact the way we perceive reality. In the rarest of cases, they can actually cause us to see sound, taste color, or feel taste.

Related Articles

How does alcohol affect your brain?

Explore how alcohol affects your brain, from the first sip at the bar to life-long drinking habits.

(Photo by Angie Garrett/Wikimedia Commons)
Mind & Brain
  • Alcohol is the world's most popular drug and has been a part of human culture for at least 9,000 years.
  • Alcohol's effects on the brain range from temporarily limiting mental activity to sustained brain damage, depending on levels consumed and frequency of use.
  • Understanding how alcohol affects your brain can help you determine what drinking habits are best for you.
Keep reading Show less

Scientists sequence the genome of this threatened species

If you want to know what makes a Canadian lynx a Canadian lynx a team of DNA sequencers has figured that out.

Surprising Science
  • A team at UMass Amherst recently sequenced the genome of the Canadian lynx.
  • It's part of a project intending to sequence the genome of every vertebrate in the world.
  • Conservationists interested in the Canadian lynx have a new tool to work with.

If you want to know what makes a Canadian lynx a Canadian lynx, I can now—as of this month—point you directly to the DNA of a Canadian lynx, and say, "That's what makes a lynx a lynx." The genome was sequenced by a team at UMass Amherst, and it's one of 15 animals whose genomes have been sequenced by the Vertebrate Genomes Project, whose stated goal is to sequence the genome of all 66,000 vertebrate species in the world.

Sequencing the genome of a particular species of an animal is important in terms of preserving genetic diversity. Future generations don't necessarily have to worry about our memory of the Canadian Lynx warping the way hearsay warped perception a long time ago.

elephant by Guillaume le Clerc

Artwork: Guillaume le Clerc / Wikimedia Commons

13th-century fantastical depiction of an elephant.

It is easy to see how one can look at 66,000 genomic sequences stored away as being the analogous equivalent of the Svalbard Global Seed Vault. It is a potential tool for future conservationists.

But what are the practicalities of sequencing the genome of a lynx beyond engaging with broad bioethical questions? As the animal's habitat shrinks and Earth warms, the Canadian lynx is demonstrating less genetic diversity. Cross-breeding with bobcats in some portions of the lynx's habitat also represents a challenge to the lynx's genetic makeup. The two themselves are also linked: warming climates could drive Canadian lynxes to cross-breed with bobcats.

John Organ, chief of the U.S. Geological Survey's Cooperative Fish and Wildlife units, said to MassLive that the results of the sequencing "can help us look at land conservation strategies to help maintain lynx on the landscape."

What does DNA have to do with land conservation strategies? Consider the fact that the food found in a landscape, the toxins found in a landscape, or the exposure to drugs can have an impact on genetic activity. That potential change can be transmitted down the generative line. If you know exactly how a lynx's DNA is impacted by something, then the environment they occupy can be fine-tuned to meet the needs of the lynx and any other creature that happens to inhabit that particular portion of the earth.

Given that the Trump administration is considering withdrawing protection for the Canadian lynx, a move that caught scientists by surprise, it is worth having as much information on hand as possible for those who have an interest in preserving the health of this creature—all the way down to the building blocks of a lynx's life.

Why cauliflower is perfect for the keto diet

The exploding popularity of the keto diet puts a less used veggie into the spotlight.

Purple cauliflower. (Photo: Shutterstock)
Surprising Science
  • The cauliflower is a vegetable of choice if you're on the keto diet.
  • The plant is low in carbs and can replace potatoes, rice and pasta.
  • It can be eaten both raw and cooked for different benefits.
Keep reading Show less