Speaker 1: Why do some people think that the Northern lights make
Speaker 1: noise and other people say that that's impossible. And why
Speaker 1: did Pythagoras think that numbers had colors and personality? And
Speaker 1: what does any of that have to do with creators
Speaker 1: like Vladimir Nabokoff and Billie Eilish, And why do you
Speaker 1: think that a high note on the piano is brighter
Speaker 1: than a low note. Welcome to Inner Cosmos with me,
Speaker 1: David Eagleman. I'm a neuroscientist and an author at Stanford University,
Speaker 1: and I've spent my whole career studying the intersection between
Speaker 1: how the brain works and how we experience life. On
Speaker 1: today's episode, we're going to talk about how we can
Speaker 1: all experience reality a little bit differently. Okay, so this
Speaker 1: story begins in the early nineteen thirties. You've heard about
Speaker 1: the Northern lights, or maybe you've even seen them in person.
Speaker 1: They're these rippling rivers of green blue light in the sky.
Speaker 1: But here's the really strange part. About one hundred years
Speaker 1: ago some people started to make the claim that the
Speaker 1: northern lights make noise. In nineteen thirty one, in the
Speaker 1: journal Nature, a scientist named Harold's Fairdrop wrote a short
Speaker 1: paper that he called Audibility of the Aurora polaris, and
Speaker 1: he wrote, quote, it cannot be doubted that many persons
Speaker 1: have heard a distinct sound when watching a brilliant display
Speaker 1: of aurora. Communications regarding the auroral sound appear now and then,
Speaker 1: and recently.
Speaker 2: Mister J. H.
Speaker 1: Johnson has collected a great number of reports on the
Speaker 1: auroral sound in his pamphlet concern the Aurora borealis. Then,
Speaker 1: in nineteen thirty three in the journal Science, someone named
Speaker 1: Clark Garber wrote another letter on the audibility of the
Speaker 1: Aurora borealis, and Garber wrote quote, some scientists have claimed
Speaker 1: with much positiveness that the aurora emits no audible sounds.
Speaker 1: In my own mind, there can be no doubt left
Speaker 1: as to the audibility of certain types of aurora, for
Speaker 1: I have heard them under conditions when no other sound
Speaker 1: could have been interpreted as such, for no other sounds
Speaker 1: were present. And he goes on to say that he
Speaker 1: first heard about the possibility that the aurora makes sounds
Speaker 1: from the eskimos, and he says he was skeptical at first,
Speaker 1: but then he experienced this sound himself. Now I stumbled
Speaker 1: on these papers a few years ago, and I was
Speaker 1: surprised because the problem is that it's not scientifically possible
Speaker 1: for the Aurora to make sound. The Northern Lights happen
Speaker 1: because photons from the Sun are banging into gases in
Speaker 1: the Earth's upper atmosphere, and that causes all that amazing light.
Speaker 1: But those collisions are happening eighty kilometers up in the sky,
Speaker 1: which means that even if there were sound, it would
Speaker 1: take about four minutes for that sound to get down here.
Speaker 1: And yet people who claim to hear the sound say
Speaker 1: they see it happening in lockstep with the lights. And
Speaker 1: more importantly, for sound to travel it needs a medium
Speaker 1: like air, and that's because sound moves as compression of
Speaker 1: the air. In other words, molecules in the air get
Speaker 1: pushed closer together and farther apart, and that's what a
Speaker 1: sound wave is. But at the altitude where the Northern
Speaker 1: Lights come into being, the atmosphere is essentially a vacuum.
Speaker 2: So this means there's probably no.
Speaker 1: Sound happening even up there, and if there were, it
Speaker 1: couldn't get all.
Speaker 2: The way to us until four minutes later.
Speaker 1: So this became a top of debate because as time
Speaker 1: went on, thousands of Arctic explorers listened carefully for these
Speaker 1: sounds but didn't hear anything. So this idea of the
Speaker 1: northern lights making noise came to be understood as a superstition.
Speaker 1: So what was happening here? Were some people simply lying
Speaker 1: in scientific journals It's happened before, But it seems that
Speaker 1: some people really believed and still believe, the lights make sound,
Speaker 1: even though the physics don't seem to allow that. So
Speaker 1: worse Ferdrup and Garber lying, were they looking for attention
Speaker 1: that they somehow have better hearing? Even today? This is
Speaker 1: contentious in geophysics. Some people argue from their personal experience
Speaker 1: that it happens, and others point out that it simply can't.
Speaker 1: To unpack this mystery, let's jump back even farther back
Speaker 1: another twenty five hundred years to Pythagoras. Pythagoras was one
Speaker 1: of Greece's most famous philosophers, and he massively influenced the
Speaker 1: trajectory of Western thought through his religious teachings his political teachings.
Speaker 1: In part this was due to his influence on Plato
Speaker 1: and Aristotle. But you've probably heard of Pythagoras because of
Speaker 1: his love of numbers. He loved geometry and theories about
Speaker 1: instrument tuning and the theory of proportions, and you'll probably
Speaker 1: remember the Pythagorean theorem from school in a right triangle,
Speaker 1: A squared plus B squared equals C squared. But there
Speaker 1: was something very odd about Pythagoras's relationship with numbers. I'm
Speaker 1: going to quote from the Yale historian Robert Brumbaugh, who
Speaker 1: notes that for Pythagoras quote, each number had its own personality,
Speaker 1: masculine or feminine, perfect or incomplete, beautiful or ugly. For Pythagoras,
Speaker 1: ten was the very best number. This feeling modern mathematics
Speaker 1: has deliberately eliminated, but we still find overtones of it
Speaker 1: in fiction and poetry. Now, how could numbers have gender
Speaker 1: and personality? Did Pythagoras have fundamental insight about numbers that
Speaker 1: the rest of us couldn't see? Or was he making
Speaker 1: up stuff to impress his followers, or was he mentally
Speaker 1: ill or taking drugs. The way that he personified numbers
Speaker 1: is traditionally discussed as an interesting oddity, or occasionally you'll
Speaker 1: find numerologists who cite Pythagoras's view as evidence that he
Speaker 1: had a cosmic insight into the true natures of numbers.
Speaker 1: I've seen websites that springboard from Pythagoras's number personalities to
Speaker 1: sell new age models of the nature of the universe.
Speaker 1: But most people don't believe that the number five has
Speaker 1: a gender or a personality. So what was going on
Speaker 1: here and what does this have to do with the
Speaker 1: scientists who claim to hear sounds from the Northern Lights.
Speaker 1: The answer to both these mysteries is related to something
Speaker 1: I'm going to discuss a lot across many episodes of
Speaker 1: this podcast, and that is the difference in people's internal worlds.
Speaker 1: We all like to believe that our experience of the
Speaker 1: world is the same as everyone else's. But the key
Speaker 1: to unlocking the mystery of the Northern Lights or Pythagoras's
Speaker 1: view of numbers is to understand that people can have
Speaker 1: very different realities on the inside. The interesting part, as
Speaker 1: we'll see, is that we accept the reality presented to us.
Speaker 1: Your brain constructs a story about what's going on out there,
Speaker 1: and you accept that as your reality. So imagine I
Speaker 1: showed you a picture of a crowd of people. If
Speaker 1: you're color blind, all you see are shades of gray.
Speaker 1: If you're not colorblind, you see it in full color.
Speaker 1: But either way, that's the reality that you know. And
Speaker 1: we now know that a very tiny fraction of the
Speaker 1: female population doesn't just have three types of color photoreceptors
Speaker 1: in their eyes, but they have four types because of
Speaker 1: a mutation, and as a result, they perceive colors that
Speaker 1: the rest of us can't even imagine. Their reality is different.
Speaker 1: So the key is we accept whatever reality our brains
Speaker 1: serve up to us. Okay, So this all leads to
Speaker 1: a very old philosophical question which I think everyone has
Speaker 1: asked at some point in their lives. How do you
Speaker 1: know that what I see as blue is what you
Speaker 1: see as blue? My parents taught me to call that
Speaker 1: thing blue, and your parents taught you to call it blue.
Speaker 2: Two. But inside your.
Speaker 1: Head and inside my head, it might be a different experience.
Speaker 2: Right.
Speaker 1: I might be seeing it as what you would think
Speaker 1: of as green, But it doesn't matter, and we'd never
Speaker 1: know as long as we can transact in the outside world.
Speaker 1: In other words, if I say, hey, can you pass
Speaker 1: me that blue thing, and we both call it blue,
Speaker 1: then the word suffices, even if we're having a different
Speaker 1: internal experience and it turns out. The situation might be
Speaker 1: even worse than that. It may be that what I
Speaker 1: call vision and what you call vision are totally different.
Speaker 1: I might see the world completely upside down from the
Speaker 1: way that you see the world, and it wouldn't matter
Speaker 1: as long as we can agree on things out there,
Speaker 1: and I can throw a ball and you can catch it.
Speaker 1: So what my colleagues and I have worked on for
Speaker 1: years is taking this question or we having different lives
Speaker 1: on the inside and elevating that from the realm of
Speaker 1: phys sophical speculation to actual scientific experiment. And one way
Speaker 1: to get at that this was something my lab is
Speaker 1: studied for fifteen years called sinnesthesia. Synesthesia is a condition
Speaker 1: in which one person might be seeing reality a little
Speaker 1: bit differently from another. So you know the word anesthesia,
Speaker 1: that means no feeling. Synesthesia means joined feeling. It's a
Speaker 1: blending of the senses. Now, there are many forms of synesthesia,
Speaker 1: and one of the most common is where a person
Speaker 1: looks at numbers or letters and that triggers an internal
Speaker 1: experience of color. So for a given synesthete, her eight
Speaker 1: might trigger the experience of blue. She still sees the
Speaker 1: number eight on the page. There if I were to
Speaker 1: write eight with black ink on a white page, she'd
Speaker 1: say that she can see the number, but seeing the
Speaker 1: number eight triggers a blue experience, an internal experience of blue.
Speaker 1: And it's just self evidently true for her that eight
Speaker 1: and blue are connected. Now this isn't just a memorized
Speaker 1: thing that she says, but it's an actual experience. And
Speaker 1: for her, maybe five is yellow, and Saturday is orange,
Speaker 1: and November is purple and so on. Now, the first
Speaker 1: thing to note is that sequences that we learn, like
Speaker 1: letters and numbers and weekdays and months, these are drilled
Speaker 1: into the brain really deeply. They're known in the field
Speaker 1: as overlearned sequences, and these are the things that trigger synesthesia.
Speaker 1: And interestingly, this often goes beyond color in when flavor
Speaker 1: of synesthesia, sequences come to have gender and personality and
Speaker 1: other qualities. So one cynesthete describes the number three as
Speaker 1: a vain, elitist girl, while seven is a shy, wimpy boy.
Speaker 1: This same cynisthe described by my colleague Sean Day. She
Speaker 1: also noted that she doesn't like certain number combinations, like
Speaker 1: ninety four.
Speaker 2: That quote result.
Speaker 1: In putting four, which is a plain but decent, hardworking
Speaker 1: older woman and nine together as they greatly dislike each
Speaker 1: other and do not get along well. And this is
Speaker 1: what was going on with Pythagoras. He had this not
Speaker 1: uncommon form of synesthesia, but his followers didn't know this,
Speaker 1: so they presumably thought he was tapped into some cosmic
Speaker 1: truth about numbers. He obviously liked numbers, but that doesn't
Speaker 1: mean he had access to some deeper significance that others didn't.
Speaker 1: How do we know that, Because each person with this
Speaker 1: particular type of synesthesia has a different association between a
Speaker 1: particular number and a gender personality. So you might think
Speaker 1: three is male and kind, and someone else might think
Speaker 1: three is female and a bit of a comic, and
Speaker 1: so on. There is no right answer. So we're gonna
Speaker 1: come back to this in a moment, But first I
Speaker 1: want to tell you about some other forms of synesthesia.
Speaker 1: It's not just colors or genders or personalities triggered by
Speaker 1: overlearned sequences. There's also a flavor of synesthesia in which
Speaker 1: what you hear causes a visual experience. So you might
Speaker 1: listen to music and that causes you to see moving
Speaker 1: shapes or colors. In my book, Wednesday's Indigo Blue. I
Speaker 1: have a picture of a shape that looks like a
Speaker 1: colorful caterpillar, and this is what one synesthete sees. She
Speaker 1: actually sees this when her furnace kicks on and goes whoosh.
Speaker 1: She has this visual experience that flashes for her. Her
Speaker 1: visual system gets tickled by the noise, and senses can
Speaker 1: be triggered in the other direction, where something visual leads
Speaker 1: to a sound. For some people, when they watch movement
Speaker 1: like a swarm of moving birds or an electric sign blinking,
Speaker 1: they feel like they hear a sound with it. They
Speaker 1: don't see the motion by itself. Their brain imposes sound
Speaker 1: on top of that. It's impossible to separate the motion
Speaker 1: and the sound. And I've proposed that this is the
Speaker 1: solution to the mystery of the Northern lights. It's impossible
Speaker 1: from a physics point of view for the lights to
Speaker 1: be making synchronized noise. But what is possible is for
Speaker 1: a small fraction of the population to be cinnesthetic, such
Speaker 1: that when they see the beautiful moving lights, they hear sound.
Speaker 1: And because of their assumption that our senses tell us
Speaker 1: the truth and that everyone should be having the same experience,
Speaker 1: this has led to over a century of debate about
Speaker 1: whether the lights make noise or not, because if your
Speaker 1: sphare drop or Gerber or any of the others who
Speaker 1: hear the sounds, you'll sit down and you'll write a
Speaker 1: letter to nature or science and insist that you can
Speaker 1: hear it. The important lesson is that we all assume
Speaker 1: our senses tell us the truth and that everyone is
Speaker 1: tapped into the same reality. But when we realize that's
Speaker 1: not necessarily the case, we can take a higher view
Speaker 1: on the scientific literature and look at all these papers
Speaker 1: going back and forth about whether the northern lights make noise,
Speaker 1: and we can understand the game at a different level.
Speaker 1: For most people the answer is no, they don't make noise,
Speaker 1: and for some it's yes. Beyond the relationship of sound
Speaker 1: and vision, there are dozens of forms of synesthesia. My
Speaker 1: colleagues and I have found that essentially any sense that
Speaker 1: you can imagine can be mixed with another. One form
Speaker 1: of synesthesia involves tastes shapes, So when people taste something,
Speaker 1: it makes them feel like they're touching something with their fingertips.
Speaker 1: So you might take a sip of soup and you
Speaker 1: feel something cold and pointy on your fingertips. Or one
Speaker 1: guy determines whether his chicken is cooked right this way.
Speaker 1: He tastes it and judges by what he's feeling on
Speaker 1: his fingertips, is it smooth or glassy or spiky. He
Speaker 1: comes to be a good cook that way. And there's
Speaker 1: also musical synesthesia. For a lot of people, different notes
Speaker 1: of the scale will trigger a color experience. For one
Speaker 1: cynisthee that I test in the lab, when she hits
Speaker 1: the note A on the piano, that's pink, the note
Speaker 1: B is blue. C is goldish white like sunlight. B
Speaker 1: is silvery white like moonlight. E is fiery orange, and
Speaker 1: so on, So she experiences very specific colors that get
Speaker 1: triggered when she hears specific notes. And I know a
Speaker 1: professional drum tuner who goes around for all the famous
Speaker 1: rock and roll bands and tunes their drums, and he
Speaker 1: does it with color, so he can tell if the
Speaker 1: drum is a little bit sharp or a little bit
Speaker 1: flat by the color that he sees in response to
Speaker 1: the sound. Now, not all people with music synesthesia have
Speaker 1: their percepts triggered by a pitch a note. For some people,
Speaker 1: it's the interval between notes like a chord that matters.
Speaker 1: So for one woman, different chords trigger different, very particular
Speaker 1: tastes in the mouth. In a paper in the journal Nature,
Speaker 1: she reported that she uses these sinnesthetic associations to identify
Speaker 1: which chord was just played. And synesthesia can also be
Speaker 1: triggered by an instrument's tamber, the way that it sounds.
Speaker 1: So when a person hears the music of a violin
Speaker 1: versus a tuba, versus a cello versus a flute, the
Speaker 1: timbre of the instrument can trigger very different experiences in
Speaker 1: terms of colors or visualized shapes or whatever. So two
Speaker 1: people might listen to a clarinet playing and that triggers
Speaker 1: different internal experiences. One of them sees it as a flat,
Speaker 1: horizontal shape with spring like protrusions sticking out, and the
Speaker 1: other person sees it as a thick ribbon that's oscillating,
Speaker 1: and so on. For different cinisthetes. And beyond shapes or colors,
Speaker 1: it can trigger other notions as well, like personalities. One
Speaker 1: cinis The reports that the obo is quote profoundly emotional
Speaker 1: and thoughtful, with drawn, introspective, and prone to melancholy, while
Speaker 1: she describes the flute as quote feminine, sweet, innocent, naive
Speaker 1: the personalities of the different instruments. They're not generic, they're
Speaker 1: rich and detailed. The triggered perception can also be a
Speaker 1: physical sensation, like a physical state of your body. For
Speaker 1: one Cyniceitt that I interviewed, different chords make her feel
Speaker 1: like her body is in different positions physically, So when
Speaker 1: she feels one chord, she feels like she's standing upright
Speaker 1: with her feet on the ground, or stepping onto a
Speaker 1: stare or soaring in the sky. She happens to be
Speaker 1: a professional musician, so when she's memorizing a piece of music,
Speaker 1: it's like memorizing a series of dance moves. And there's
Speaker 1: one more form, which is likely the most common, around
Speaker 1: ten percent of the population experience it. It's when people
Speaker 1: perceive sequences like the days of the week or the
Speaker 1: months of the year, as though they have a specific
Speaker 1: space location in relation to their body, like March is
Speaker 1: off here to the left, and April is next to it,
Speaker 1: and May is a little bit higher and off next
Speaker 1: to that. For every month or a weekday or numbered
Speaker 1: things like that, they have a specific spatial location that
Speaker 1: the person can identify where it seems to them that
Speaker 1: the thing exists. It's just self evidently true to them
Speaker 1: that that member of the sequence has that particular spatial location.
Speaker 1: This form of synesthesia is not a hallucination. It's not
Speaker 1: that you actually see April right there visually.
Speaker 2: It's that it's just obviously true to you.
Speaker 1: That April would occupy that spatial location to you. It
Speaker 1: would be like if I asked you to imagine an
Speaker 1: apple five feet in front of you. So you're picturing
Speaker 1: the apple there and it's got a particular spatial location
Speaker 1: with respect to your body, and you can imagine it,
Speaker 1: but you're not actually hallucinating it. But if I ask
Speaker 1: you where that apple is, that's the spatial location that
Speaker 1: it has. A lot of people have this form of
Speaker 1: synesthesia for years, like the year nineteen seventy nine has
Speaker 1: a specific spot in space and relation to your body,
Speaker 1: as does twenty twenty one or twenty fifty seven and
Speaker 1: everything in between, and the years sit on this spatial timeline.
Speaker 1: The timeline isn't necessarily straight. It can curve or take
Speaker 1: sharp turns, and it typically moves with the passing of
Speaker 1: each year. Now, what's interesting is that for many cinisthetes,
Speaker 1: a year in the past moves behind them, say the
Speaker 1: year twenty twenty one. Why because that year has already happened,
Speaker 1: so it moves behind you, while a year like twenty
Speaker 1: forty two is often the distance ahead of you. But
Speaker 1: for other cynisthetes, it's exactly flipped. A year in the
Speaker 1: past is in front of them because they already know
Speaker 1: what happened in twenty twenty one, but year like twenty
Speaker 1: forty two hasn't happened yet, so they don't know anything
Speaker 1: about it. It's as invisible to them as an object
Speaker 1: that is behind them. I'll just note that another research
Speaker 1: group called this form of synesthesia time space synesthesia because
Speaker 1: they looked at things like weekdays and months and years
Speaker 1: and said, hey, those all have something to do with time.
Speaker 1: But I want to emphasize that this is not the
Speaker 1: correct way to understand this, because this same spatialization happens
Speaker 1: with number lines like one, two, three is over here,
Speaker 1: that it takes a right turn here for four through seven,
Speaker 1: then eight, nine, ten climb straight up, then eleven through
Speaker 1: twenty shoot off in a straight line, and then twenty
Speaker 1: one through thirty are stacked above that like that.
Speaker 2: Kind of thing.
Speaker 1: And also we find cinisthetes who have spatialization for the
Speaker 1: Indian caste system, or shoe sizes, or temperatures, or historical
Speaker 1: eras or primetime television line. So it can be anything
Speaker 1: that's a sequence, and it just so happens that time
Speaker 1: is sequential, but it's just a subset of the sequences
Speaker 1: that you might learn in life. And that's why I
Speaker 1: named this spatial sequence synesthesia in the literature, which is
Speaker 1: the name now used in the field. It turns out
Speaker 1: there are many, many forms of synesthesia, and one group
Speaker 1: has estimated that there are one hundred and fifty two
Speaker 1: different forms that have been reported. So anything you can imagine,
Speaker 1: any kind of cross blending between the senses has been
Speaker 1: reported at one point or another.
Speaker 2: Beyond the spatial sequence synesthesia.
Speaker 1: The next most common one seems to be the letters
Speaker 1: or numbers mapping on to colors, or weekdays and months
Speaker 1: to colors, or musical sounds to colors, or smells to colors,
Speaker 1: or taste to colors. Most forms of synesthesia trigger color,
Speaker 1: but we also find triggered tastes, smells, sounds, temperatures, emotions,
Speaker 1: and so on. We find essentially any kind of cross
Speaker 1: sensory blending that you can think of. It appears that
Speaker 1: synesthesia is different for every synesthet Her associations are different
Speaker 1: from hers, are different from hers. So the color that
Speaker 1: gets triggered by the letter J or the number three
Speaker 1: is a different color for everyone. Now why is this.
Speaker 1: It could be that it's just about random wiring in
Speaker 1: the brain, so the particular letter that matches up to
Speaker 1: a particular color is arbitrary. But my colleagues and I
Speaker 1: started to wonder if instead of randomness, it could be
Speaker 1: about something that you imprinted on as a young child. Now,
Speaker 1: this would give essentially the same results as randomness, because
Speaker 1: you might, as a child see an alphabet quilt that
Speaker 1: your mother made, and your mother's choices were just her
Speaker 1: random choice, or an alphabet poster that your teacher made
Speaker 1: at your preschool with some random choice, or some ad
Speaker 1: in a magazine, and the idea is that those particular
Speaker 1: letter color associations stuck for you. For most brains, the
Speaker 1: statistics wash out, which means that one day you see
Speaker 1: an A that's red, and the next day you might
Speaker 1: see an A that's blue, and the next day yellow,
Speaker 1: and so on, and so your brain learns that A
Speaker 1: is not associated with any particular color, but in a
Speaker 1: synesthetes brain, for whatever reason, perhaps the first association that
Speaker 1: they see sticks and doesn't get washed out. Now, how
Speaker 1: could you possibly test for this imprinting given that there's
Speaker 1: no easy way to know what people saw in their childhoods?
Speaker 1: And this is where science comes in. I collected detailed
Speaker 1: colored alphabets from almost seven thousand cynisthetes who had these
Speaker 1: colored alphabets, and with two colleagues at Stanford, we analyzed
Speaker 1: those colors in detail, like person number one has a
Speaker 1: red A and a purple B and a yellow C
Speaker 1: and so on, and the next person has a brown
Speaker 1: A and a crimson B and a gold C and
Speaker 1: so on. So we analyzed this huge pool of cynisthetes
Speaker 1: and we found something amazing. At least six percent of
Speaker 1: the cynisthes had approximately the same colors. A through F
Speaker 1: went red, orange, yellow, green, blue, purple, and then this
Speaker 1: same sequence of colors was repeated G through L, and
Speaker 1: then M through R and so on till the end
Speaker 1: of the alphabet. This was so weird, and even more
Speaker 1: of a clue is that we looked at people's birth
Speaker 1: year and this sequence of colors never came up for
Speaker 1: people who were born before the late nineteen sixties, and
Speaker 1: then the proportion of people started to rise. So for
Speaker 1: cyniesites born between nineteen seventy and nineteen eighty five, fifteen
Speaker 1: percent of them had this same sequence of colors for
Speaker 1: their letters, and then for those born after nineteen ninety
Speaker 1: the proportion decreased again. So what was going on here?
Speaker 1: We figured it out. In nineteen seventy one, a new
Speaker 1: toy started finding its way into homes all over the
Speaker 1: United States. It was the Fisher Price magnet set. This
Speaker 1: was a set of refrigerator magnets that consisted of the
Speaker 1: letters of the alphabet, and each one was colored and
Speaker 1: it cycled through the letters red, orange, yellow, green.
Speaker 2: Blue, purple.
Speaker 1: So for those born in the decade after the magnets existed,
Speaker 1: this color pattern reached fifteen percent. But for those who
Speaker 1: grew up before the magnets existed, not a single one
Speaker 1: of them had this pattern. So for all of these cyinsetes,
Speaker 1: it was about whether they were exposed to these magnets
Speaker 1: as children. Now, I want to be really clear that
Speaker 1: the synesthesia wasn't caused by the Fisher price alphabet set
Speaker 1: because the rest of the population saw it in the
Speaker 1: seventies and eighties, but only three percent of people become cynisthetes.
Speaker 1: It's simply that the sinisthetes who saw it imprinted on it,
Speaker 1: so that.
Speaker 2: To them A always.
Speaker 1: Triggers red, and B orange, and C yellow and so on.
Speaker 1: Synesthesia is something we think of as a different way
Speaker 1: of perceiving the world. It's not a disorder or a disease,
Speaker 1: because there's no disadvantage to it. In fact, in some cases,
Speaker 1: cinisthetes tend to have better memories. So if I were
Speaker 1: to tell you my phone number and you are a sinisthete,
Speaker 1: you might forget some of the digits, but you may think, oh, yeah,
Speaker 1: I remember it had a really nice autumn color pattern
Speaker 1: to it, and so that would help you to reconstruct.
Speaker 2: It later when you're trying to think of it.
Speaker 1: You may have heard the termmneminists spelled with an m
Speaker 1: N like Johnny mnemonic or a mnemonic device. Anyway, aneminist
Speaker 1: is a person with an incredible memory. They can memorize
Speaker 1: long lists of nonsense words, or really long strings of
Speaker 1: numbers or series of locations. It turns out as far
Speaker 1: as I can tell, that every single one of these
Speaker 1: mneminists have synesthesia. They can take something like the digits
Speaker 1: of Pie three point one four one five, nine, two
Speaker 1: sixty five three five, and for thenemenist this may have colors,
Speaker 1: such as the colors helped them to memorize the sequence.
Speaker 1: And more than colors, they may have also textures and
Speaker 1: personalities and genders and sizes, So as they're learning three
Speaker 1: point one four one five, nine two sixty five, there's
Speaker 1: a whole story landscape with a rich texture. So this
Speaker 1: is how they memorize Pie to thousands of digits, while
Speaker 1: for the rest of us who aren't synesthetic, for whom
Speaker 1: all numbers are essentially alike, it's an almost impossible challenge.
Speaker 1: I'll just mention that this advantage of synesthesia can also
Speaker 1: become a confusion in some circumstances. So one synesthete has
Speaker 1: particular colors that he sees for names like Mike and Dan,
Speaker 1: but it turns out that he sometimes runs into trouble
Speaker 1: at cocktail parties because it just so happens that Dave
Speaker 1: and Rob have exactly the same colors for him as
Speaker 1: Mike and Dan. So if your name is Dan, He's
Speaker 1: pretty likely to mess up and call you Rob later
Speaker 1: in the night. It turns out many artists have synesthesia.
Speaker 1: Vasili Kandinsky was a music to color cinesthete. So if
Speaker 1: you can picture a Kandinsky painting, you know that he
Speaker 1: has these bold brushstrokes and vibrant colors. He makes these
Speaker 1: abstracts with a sense of movement and energy. Boy, you
Speaker 1: might not know is how he made them. He would
Speaker 1: crank up his phonograph and he would stand in front
Speaker 1: of his canvas and paint the images that came to
Speaker 1: his head from the music that he was hearing. So
Speaker 1: what you see on the canvas are his renditions of
Speaker 1: his synesthetic experience. And many writers are cynisthetes. Vladimir Nabokov,
Speaker 1: who wrote Lolita, was very synesthetic with letters and numbers.
Speaker 1: These would trigger colors for him, and as a young
Speaker 1: man he actually wrote quite a bit of poetry about
Speaker 1: how he saw letters. When he was asked what color
Speaker 1: his own initials were, the Bokhoff answered quote, the D
Speaker 1: is a kind of pale, transparent pink. I think it's
Speaker 1: called technically quartz pink. This is one of the closest
Speaker 1: colors that I can connect with the V, and the N,
Speaker 1: on the other hand, is a grayish yellowish oatmeal color. Interestingly,
Speaker 1: different colors were triggered for him by the same letter
Speaker 1: in different languages, so he said, quote the long A
Speaker 1: of the English alphabet has for me the tint of
Speaker 1: weathered wood, but a French A evokes polished ebony. This
Speaker 1: black group also includes hard G, vulcanized rubber and R,
Speaker 1: a sooty rag being ripped, oatmeal, N noodle, limp L,
Speaker 1: and the ivory backed hand mirror of an O. Take
Speaker 1: care of the whites. I am puzzled by my French on,
Speaker 1: which I see as the brimming tension surface of alcohol
Speaker 1: in a small glass. As a side note, Thebokoff loved butterflies,
Speaker 1: and one of his favorites had yellow wings in a
Speaker 1: black middle. So when yellow black yellow, and that corresponded
Speaker 1: for him to the letters ab a so boom. That
Speaker 1: became the title for his great novel Aida. It was
Speaker 1: his little insider synesthetic joke, and many musicians are synesthetic.
Speaker 1: Take Amy Beach, who was the first successful American female composer.
Speaker 1: Her biographer noted that for her, C was white and
Speaker 1: F sharp was black. And e was yellow and so on.
Speaker 1: Until the end of her life she associated those colors
Speaker 1: with those notes. Or The composer Olivier Mession, he was synesthetic,
Speaker 1: and he described his purpose as quote, painting the visible
Speaker 1: world in sound. He would describe things in his diary like, quote,
Speaker 1: the gentle cascade of blue orange chords. This is the
Speaker 1: way that he would describe particular sequences of music. There
Speaker 1: are lots of musicians with synesthesia. Billy Joel, Duke, Ellington, Torry,
Speaker 1: Amos Grimes. The singer Billy Eilish recently told Rolling Stone quote,
Speaker 1: every person that I know has their own color and
Speaker 1: shape and number in my head, but it's normal to me.
Speaker 1: She says that her brother Phineas is an orange triangle,
Speaker 1: although his name Phineas is dark green. Pharrell Williams also
Speaker 1: has synesthesia. For him, each note has a color, and
Speaker 1: his musical group Nerd named one of their albums Seeing Sounds.
Speaker 1: Now people have speculated, because of this sort of thing,
Speaker 1: that maybe there's an overrepresentation of sinnisthetes in the artistic community.
Speaker 1: But I just want to point out that we don't
Speaker 1: actually know if that's true, because no one's ever gone
Speaker 1: in and tested the community of accountants or deep sea divers.
Speaker 1: All we know is that we can point to a
Speaker 1: lot of artists who are synesthetic, and so we can
Speaker 1: hypothesize that maybe synesthesia provides some pull to those professions.
Speaker 1: In other words, if you have this slightly richer sort
Speaker 1: of perception, then maybe you gravitate towards certain sorts of pursuits.
Speaker 1: By the way, I should note that not every artist
Speaker 1: who does something synesthetic is actually a synisthet The composer
Speaker 1: Scriabin was really interested in the effects of putting sound
Speaker 1: and color together, and he thought that would provide a
Speaker 1: really strong resonance for the listener. So he invented a
Speaker 1: color organ. When you hit the notes, you're not only
Speaker 1: playing the musical sound, but there are spotlights of different
Speaker 1: colors coming out of the top. But Screopin wasn't actually
Speaker 1: a synisthete himself he was just exploring cool things and
Speaker 1: was influenced by the fashions of the art world at
Speaker 1: that moment. So not everyone who does this sort of
Speaker 1: thing is actually a synesthee. And this leads me to
Speaker 1: a really important point. How can you tell if someone
Speaker 1: really is synesthetic? How can you test for this. So
Speaker 1: when someone tells you that they're a synisthete, how could
Speaker 1: you ever know if they're just being artistic or metaphorical
Speaker 1: or poetic, or lying or just trying to get attention.
Speaker 1: So my colleagues and I, over the past fifteen years,
Speaker 1: have developed a whole series of tests where we can
Speaker 1: show when synesthesia is actually a real perceptual experience. And
Speaker 1: I want to tell you how we do that. It
Speaker 1: has everything to do with the consistency of people's perceptions.
Speaker 1: So if you're a cynisthete who sees eight as lavender,
Speaker 1: you're always going to see it as lavender. But if
Speaker 1: I were to ask you to make up some colors
Speaker 1: right now, and then I ask you again a year
Speaker 1: from now, if you're not synesthetic, you're not going to
Speaker 1: be able to get these same color associations. But if
Speaker 1: you are synesthetic, it'll be the same colors. So many
Speaker 1: years ago I launched a website called cinnisthete dot org,
Speaker 1: and it's a battery of tests that are freely available.
Speaker 1: So if you think you might be a synthete, go
Speaker 1: to the site and take the tests. What we can
Speaker 1: do this way is rigorously determine who exactly is synesthetic
Speaker 1: and who's not. Here's the method. It has anything to
Speaker 1: do with internal consistency. So we show you a letter
Speaker 1: of the alphabet at random, say a J, and you
Speaker 1: see a color palette on the screen, and by moving
Speaker 1: a slider around, you can get to any hue, any color,
Speaker 1: and by moving a second slider around, you can specify
Speaker 1: whatever saturation, in other words, how dark or bright it is.
Speaker 1: So you pull the sliders around and you pick the
Speaker 1: color that best matches your synesthetic perception for that letter.
Speaker 1: And this is out of sixteen million different colors that
Speaker 1: can be displayed on a computer screen. And when you
Speaker 1: found the best one, you click submit, and then you
Speaker 1: get the next random letter or number, say the letter
Speaker 1: W or the number three or whatever, and you find
Speaker 1: exactly that color that best matches for that one. And
Speaker 1: the trick is we present you with each letter and
Speaker 1: each number three times, each in random order. So the
Speaker 1: idea is that if you are really a synesthee, you're
Speaker 1: going to land on the same shade of color for
Speaker 1: let's say the letter J every time. And if you're
Speaker 1: a sinisthete, it turns out it's very hard to fake that.
Speaker 1: So when you look at the results for cynisthetes and
Speaker 1: for control subjects who are asked to fake synesthesia, we
Speaker 1: can measure the amount of difference in the colors that
Speaker 1: they chose. And what we see is that for a
Speaker 1: real cinisthete, it's easy. Every time she's presented with the
Speaker 1: letter T, she picks the same color or E, it's
Speaker 1: the same color every time, and so on. Whereas for
Speaker 1: somebody who's asked to use free association or memory or
Speaker 1: whatever but they're not actually synesthetic, it's really difficult to
Speaker 1: get the same colors. It's a very hard test to
Speaker 1: pass to remember what you said fifty seven trials ago
Speaker 1: and find that color again out of sixteen million possible colors.
Speaker 1: So this turns out to be a powerful way that
Speaker 1: we can distinguish who is a cynisthete and who is not.
Speaker 1: And we actually have several levels of testing to make
Speaker 1: it absolutely impossible to cheat. So, for example, after we've
Speaker 1: collected your colors, we then flash it to you on
Speaker 1: the screen. So let's say it's the letter H. We
Speaker 1: flash an H that's either the color that you've had
Speaker 1: chosen or a different color from somewhere else in your palette,
Speaker 1: and you have to say as quickly as you can
Speaker 1: whether it matches or didn't match your perception. And for
Speaker 1: a real cynisthete, if I'm flashing the orange h they'll say, yeah,
Speaker 1: that match, and if I flash a green age, they'll
Speaker 1: say that doesn't match. But for someone who's just faked
Speaker 1: their way through, it's something they're terrible at, both in
Speaker 1: terms of accuracy and reaction time. So this is how
Speaker 1: we can make sure that we find real cynisthetes. And
Speaker 1: we've translated this battery into many different languages, including Chinese
Speaker 1: and Hebrew as well as a whole bunch of European languages,
Speaker 1: and this way we can find out what's going on
Speaker 1: not only in French and Spanish and German, but also
Speaker 1: in different alphabetic systems like Cyrillic or Hebrew or Chinese.
Speaker 1: Also we can test all sorts of different forms of synesthesia.
Speaker 1: And what we have now are about eighteen different forms
Speaker 1: of tests, like musical notes to color, or instrument tambers
Speaker 1: to color and so on. And it turns out with
Speaker 1: this sort of testing we can finally get the sample
Speaker 1: sizes that we need, because it turns out that all
Speaker 1: the previous literature had a sample size of one. Up
Speaker 1: until the early two thousands, it was all single case
Speaker 1: studies where people said, hey, I met a cinisthet and
Speaker 1: I asked her these questions and here are her answers.
Speaker 1: And then people started publishing papers with a participant group
Speaker 1: size of two or four, and a few papers had
Speaker 1: eight people in them. What we've done now is changed
Speaker 1: the game on that because we have rigorously verified over
Speaker 1: sixty four thousand cinisthetes and we have their data in
Speaker 1: exquisite detail, and this allows us to alter the scientific
Speaker 1: playing field. Now, there were a few papers on synesthesia
Speaker 1: in the eighteen hundreds, but then synesthesia essentially slipped out
Speaker 1: of the scientific spotlight for most of the twentieth century,
Speaker 1: and that was because psychology was dominated by the behaviorist
Speaker 1: school of thought, where the idea was that we're just
Speaker 1: input output reflex machines and it wasn't really appropriate or
Speaker 1: scientific to talk about private subjective experience. So as a result,
Speaker 1: synesthesia fell to the wayside. But fundamentally, if there's one
Speaker 1: thing we know, it's that it feels like something to
Speaker 1: have a brain. We have private subjective experience consciousness, and
Speaker 1: so as this question has become a serious one in
Speaker 1: our field. Synesthesia has risen from the ashes as a
Speaker 1: powerful inroad to understanding consciousness. So what causes synesthesia? My
Speaker 1: colleagues and I have performed brain imaging and what we
Speaker 1: found is that in a cynisthete, neighboring areas of the
Speaker 1: brain have a little bit more cross.
Speaker 2: Talk than normal.
Speaker 1: So regions of the brain that care about letters and
Speaker 1: numbers happen to be close to other regions that care
Speaker 1: about colors, and in a sinisthete, there's a bit more
Speaker 1: cross talk between these areas than in a typical brain.
Speaker 1: So think of it like two neighboring countries with porous borders.
Speaker 1: And some years ago my lab started a long term
Speaker 1: project to find the gene or genes that underlie synesthesia.
Speaker 1: And to my mind, this is the first step in
Speaker 1: a new subfield, which I'm calling perceptual genomics, which just
Speaker 1: means understanding the subtle genetic differences that make you see
Speaker 1: the world differently than I do. As a scientific community,
Speaker 1: we're always looking for the genes for predisposition to diabetes
Speaker 1: or aortic stenosis or Parkinson's, or that make some people
Speaker 1: taller or broader or red haired or whatever. The same
Speaker 1: techniques can be used to find the genes that make
Speaker 1: our realities a little different from one another. Something that
Speaker 1: struck me, as I mentioned earlier, is that there are
Speaker 1: many different subtypes of synesthesia. Now are these all the
Speaker 1: same thing or different? In other words, are all synesthesias
Speaker 1: due to a single genetic change or are there totally
Speaker 1: separate mechanisms involved? So how could I answer this? We
Speaker 1: tested all these thousands of people on synesthesia, and we
Speaker 1: asked from the data how the different types cluster with
Speaker 1: one another. In other words, if you have colored letters,
Speaker 1: what is the likelihood that you also have instrument tamber
Speaker 1: synesthesia or colored months or colored musical notes or something
Speaker 1: like that. How do these different things clump with each other.
Speaker 1: What we found is that if you have colored letters
Speaker 1: in number, you're really likely to have colored weekdays or months,
Speaker 1: but you're not terribly likely to have other forms of
Speaker 1: synesthesia like vision to sound or taste to touch. And
Speaker 1: what we found is that the different types fall into
Speaker 1: five different clusters.
Speaker 2: If you have touch to color.
Speaker 1: You're not really likely to have sound to touch or
Speaker 1: other types. They fall into these different groups. And if
Speaker 1: you want to know more about this, go to Eagleman
Speaker 1: dot com slash podcast to see our different papers on this. Now,
Speaker 1: this is an important finding that I'm mentioning because it
Speaker 1: suggests that synesthesia is not a single thing genetically, but
Speaker 1: there may be at least five different things that we're
Speaker 1: all putting under the same umbrella. And the reason we
Speaker 1: put them under the same umbrella is simply because they
Speaker 1: have something in common. There's a mixture of the senses,
Speaker 1: but they might actually be underpinned by different genetic bases.
Speaker 1: And this is something I'll talk about in future episodes,
Speaker 1: because we're generally seeing the same thing when we look
Speaker 1: at other things like schizophrenia. People can present clinically very differently,
Speaker 1: but we lump it all under schizophrenia. But I think
Speaker 1: it's likely that in ten years from now, we'll talk
Speaker 1: about multiple types of schizophrenia, and eventually we'll have totally
Speaker 1: new names that identify the different genetic causes that happen
Speaker 1: to give rise to these similar conditions that we stick
Speaker 1: under the same umbrella. So the one that I've been
Speaker 1: concentrating on is the one I call colored sequence synesthesia,
Speaker 1: because as I mentioned, the thing to note is that
Speaker 1: letters and numbers and weekdays and months are all overlearned sequences.
Speaker 1: They're all arbitrary sequences that you memorize when you're about
Speaker 1: four or five years old. And the way I started
Speaker 1: this genetic study was by crashing a wedding and asking
Speaker 1: everyone to spit into spitkits. Now why a wedding, It's
Speaker 1: because the whole family tree of this family with synesthesia
Speaker 1: was there, so I could march through the tree to
Speaker 1: see who has synesthesia and who doesn't, and then do
Speaker 1: what's called a family linkage analysis, which looks at how
Speaker 1: the small genetic changes march through the family tree and
Speaker 1: you find out which tiny changes are tracking with who
Speaker 1: has synesthesia. Now, we're still working on this with lots
Speaker 1: of different families in their trees, and it may well
Speaker 1: be that there are different genetic changes in different families,
Speaker 1: but we're getting closer to identifying at least some of
Speaker 1: the genes involved. Now, this might involve an increased wiring
Speaker 1: in a cineste's brain, or it might involve a slight
Speaker 1: imbalance of the inhibition and excitation in the brain such
Speaker 1: that you have activity in one area that kindles activity
Speaker 1: in the neighboring area. I actually favor the second hypoth
Speaker 1: this because non synesthetes can experience synesthesia with drugs, and
Speaker 1: people can also experience synesthesia sometimes if they're super tired
Speaker 1: and someone slams the door, they'll see colors. Even for synesthetes,
Speaker 1: there synesthesia waxes and wanes a bit. Whether they're stressed
Speaker 1: or fatigued, or on cigarettes or alcohol, or antidepressants or
Speaker 1: anti epileptics. All these things change the quality of their synesthesia.
Speaker 1: And that has the feeling of something to do with
Speaker 1: the chemical balance, not simply the hardwiring. So I think
Speaker 1: that when we find the gene or genes, will be
Speaker 1: able to show that it's something associated with the balance
Speaker 1: between inhibition and excitation in the brain. So what's amazing
Speaker 1: about synesthesia is that what might be a single nucleotide
Speaker 1: change in your genome changes the way that you see
Speaker 1: the world. It changes the way that you experience and
Speaker 1: it's your reality. So this will be the first time
Speaker 1: that we're able to say, if you change this little
Speaker 1: A or C or T or G over here, now
Speaker 1: you are seeing the world differently. Now I want to
Speaker 1: ask you a question. I'm going to play two notes
Speaker 1: on my piano, which one is brighter, which one is bigger.
Speaker 1: I've asked this informally to thousands of nonsynesthes and essentially
Speaker 1: everybody answers that the high note is brighter and the
Speaker 1: low note is larger. And that's strange, right, because all
Speaker 1: I'm doing is playing some notes, and you're mapping that
Speaker 1: sound onto brightness and onto size. So what this suggests
Speaker 1: is that everyone has some cross connectivity in the brain.
Speaker 1: And when you look at the micro anatomy, what you
Speaker 1: find is that there are fibers in the brain carrying
Speaker 1: visual information that go into the auditory part of your brain,
Speaker 1: and there's fibers carrying auditory information that plug straight into
Speaker 1: the visual parts of your brain. So this isn't everybody's brain.
Speaker 1: It turns out there's naturally a lot of mixing of
Speaker 1: the senses, and that's presumably why we all understand expressions
Speaker 1: in the language that cross the senses, like oh, that's
Speaker 1: a loud tie, or that's cool jazz, or she has
Speaker 1: a sweet personality, or that's sharp cheese. Cross sensory expressions
Speaker 1: are all over the language, and they kind of work
Speaker 1: with everybody.
Speaker 2: We all know what it means when.
Speaker 1: You talk about these So this is the sense in
Speaker 1: which we all share something like synesthesia, but we only
Speaker 1: call it synesthesia when it's a cross sensory connection. That's rare,
Speaker 1: And in this way synesthesia can serve as a terrific
Speaker 1: inroad into understanding consciousness, both what people have in common
Speaker 1: and what they experience differently. It illustrates a theme that
Speaker 1: I'm going to come back to a lot in this podcast,
Speaker 1: which is that people can be quite different on the inside. So,
Speaker 1: to wrap up today's episode, reality is not one size
Speaker 1: fits all. Two people can stand right next to each
Speaker 1: other watching the Northern lights, and for one a sound
Speaker 1: is internally triggered by the visuals, and not for the other.
Speaker 1: Two humans watching the same event and having divergent experiences.
Speaker 1: And the important lesson here is that if we're just
Speaker 1: trying to understand our own reality, we're like fish in
Speaker 1: water trying to describe water. It's impossible to describe what
Speaker 1: water is because we've never seen anything other than that.
Speaker 1: But when you see a different way that things can be,
Speaker 1: that gives you a broader platform from which to build theories,
Speaker 1: and that allows us to make progress on one of
Speaker 1: our deepest goals in neuroscience to understand how the microscopic
Speaker 1: activity in these three pounds of wet, gushy alien computational
Speaker 1: material maps onto the world that you see and enjoy
Speaker 1: every day, How it maps onto the view that you're
Speaker 1: looking at right now, or the feel of your clothes
Speaker 1: on your skin, or the sound of my voice in
Speaker 1: your ear. That's all for this week. To find out
Speaker 1: more and to share your thoughts, head over to eagleman
Speaker 1: dot com slash podcasts. If you think you might have
Speaker 1: synesthesia and you want to take the tests, go to
Speaker 1: sinnisthet dot org. Until next time, I'm David Eagleman, and
Speaker 1: this is Inner Cosmos.