Transcriber: Amanda Zhu
Reviewer: Rhonda Jacobs Okay. Let's start with an experiment. What color is the letter F? Some of you might have
checked the slide just like I did to see if there's an F up there. There isn't. Some of you might instinctively
know what color F is. What if I told you that F was the golden yellow color
of wheat fields in summer? Would you think I'd drunk
too much caffeine before coming on stage? Would you think I was just making this up? Or would you want to argue with me? Would you be thinking F isn't yellow,
F is green, or F is pink? Some of you might be
on the same page as me already, and if you're not, then allow me to welcome you
to the world of synesthesia. Synesthesia is a neurological condition, sometimes called
the cross-wiring of senses, where a stimulation of one sense - touch, taste, sound, sight - causes the experience of another. And the type of synesthesia
I've just been talking about, where F's are yellow or green or pink, is called grapheme-color synesthesia, and it's the most common kind. For people with this type of synesthesia, graphemes - so letters or numbers - have colors. And whilst these colors
might differ between individuals, for the individuals themselves, they remain the same
throughout their life. These are my personal colors,
and they don't change. Once you've got it,
you've pretty much got it forever. And these are the hallmarks
of synesthesia, and these need to be present in order for synesthesia
of any kind to be diagnosed. The synesthetic experience
must be involuntary, so it happens whether you like it or not. And it must be consistent; it remains the same throughout your life. It must be unidirectional, which means that graphemes evoke colors,
but colors don't evoke graphemes. And it must be automatic,
so it happens completely without effort. But today I'm not going to be talking
about the most common type of synesthesia; that would be far too easy - instead, I'll be talking
about synesthesia at its most rare. Some of you might have had an idea
of what I was talking about when I asked you what color is F. But what if I had said,
What shape is next week? Well, for one percent of you
in the audience - that's about 10 lucky people - this should still make perfect sense because this is what's known
as time-space synesthesia. For people with time-space synesthesia, time itself has a form, and this form takes physical shape
around the person. And sometimes this form
looks like a hula hoop or like a roller coaster, moving through and around the body. Sometimes it looks more like a halo,
encircling the head and moving as the head moves, or not, depending on the person. And these are illustrations
by time-space synesthetes themselves. The science writer Alison Motluk
describes her synesthesia as if she herself
was riding a roller coaster, starting off in January before moving down all the way
through spring and summer, and then coming back up
through autumn and winter to finish again in January. And this, as we can see, is very much a vertically
oriented synesthesia, running parallel to her body like this. In contrast, the writer Emma Yeomans talks about a horizontally
oriented synesthesia. So, on a typical working day for her, she sits firmly in the present
with her laptop whilst to her right,
tea steams into her past, and to her left, papers and notes cover her future. And this is much more
of a horizontally orientated synesthesia. But we can see that in both cases, the person remains at the center
of the synesthetic form. Now, you might be thinking this is all so far from the reality
of how I experience time. A visible personal calendar
that goes with you wherever you go might sound like something
that you have on your phone, not something that you have in your brain. But I want to suggest that actually, when we all talk about time,
we use something similar - we use metaphor. A metaphor works like this: you have an abstract concept -
let's call it X; and a concrete concept - let's call it Y. Now, in this case, time is the abstract concept
while space is the concrete concept. It's much easier for us
to get our heads around space than it is around time. Since time is too abstract
for the brain to process by itself, it needs to be given a context. And by using data gathered from the auditory, visual,
or tactile centers of the brain, we're able to judge the distance between
and the location of events that happen in time, giving these events a spatial context. And so time, X, is mapped onto space, Y. And by the way, this mapping is so powerful,
so fundamental to cognition that the act of moving in space
or even thinking about moving in space alters how we perceive time passing. Studies have shown that just imagining
moving forward in a queue or taking a train journey dramatically alters how we
perceive time in the real world. And this relationship, of course,
is reflected in our language and this universal rule
that time is space. I bet you've used at least three
or probably all of these in the past week. The deadline has been moved forward or pushed back; the time is coming. Everywhere we look, we run into this rule, that time is space. And it's this rule which allows us
to create an internal mental timeline. So how many of you have spoken about something
you wished you'd done yesterday or something that you want to do tomorrow? You might have used gestures like this to emphasize that you're talking
about the past or about the future. All of us in this room,
synesthetic or not, have a mental timeline, a preference to associate certain areas
of our personal space with the past and other areas of our personal
space with the future. And so, I will suggest
that this means time-space synesthesia, as in the external visual form, isn't actually a discrete entity; instead, it's part of a much longer
continuum on which we all sit, where at one end, the relationship between time
and space in the brain is visualized as an external form and at the other,
it's experienced internally. Think about it. This is the axis on which
we usually talk about our time. It runs like this, often through our body, so we say that we face the future
and we put the past behind us. And we can track this internal synesthesia with the principles of synesthesia
that I mentioned before. So, is it consistent? Yes, this doesn't tend to change
throughout our lives. Is it involuntary? Yes, we can't help
that we make these associations. Is it unidirectional? Yes, we need to map time onto space
because it's so abstract, but we don't need to map space onto time. And it's automatic; most of us don't even know
that we're doing it. So, congratulations,
you all have synesthesia. But you cannot go yet, unfortunately, because this isn't where the story ends. Although the relationship
between time and space might be universal, the details of that relationship
are highly mediated by the context and the culture
in which our brains develop. Okay, second experiment. Imagine that I give you
a piece of paper like this, and imagine that I ask you
to draw on that piece of paper a timeline running from your birth
to the present day. On what side of the paper
would you put your birth? Now, I'm willing to bet
that for most of you, your instinctive answer
is that you put it on the left, with the rest of your life
running across the page to the right. And I'm also willing to bet
that for most of you, your first language,
the one you grew up speaking, runs from left to right across the page. And my final bet is that if I'm wrong
about your first language, then I'm also wrong
about the placement of your birth, since studies have shown that those whose first language
runs from right to left, like Arabic, are more likely to put the event
of their birth on the right of the page. And this means that the mental timeline
I was just talking about, running like this, isn't universal at all. It was thought to be for a long time, but it's recently been discovered that different cultures visualize time
as running along axes as varied as left to right, right to left,
up to down, back to front, even north to south and east to west. So here's an example. The Pormpuraawan are an Indigenous
Aboriginal community in Australia, and if you ask a Pormpuraawan individual to order photos of a person aging
in order from the youngest to the oldest, they will invariably put the oldest photos
of the person on the west and the youngest photos to the east. And this is regardless of where they are
in the room or their orientation; they know where west and east is, and they will order the photos
in those directions. So for the Pormpuraawan,
time itself runs from east to west. And for the Aymara of the Andes, time runs along a similar axis
as it does for us, but it's reversed. So the Aymara logic is,
well, we've experienced the past - we know it, we've seen it - so it should lie in front,
where we can look at it, whilst the future, which remains unknown, lies behind us. So for the Aymara, future events sit here,
and past events sit here. And this is reflected, as it is for us
in English, in their language. So the Aymara word for "last year"
literally means front year, or side year. But I think the most fascinating example
of this variation in timelines comes from the Yupno people
of Papua New Guinea. And the Yupno are geographically isolated
by a very steep mountain range, so their access to lots
of Western technologies, like clocks and calendars, as well as electricity
and domestic animals, is highly limited. And the Yupno express their time
according to their landscape. A team of anthropologists
living with the Yupno noticed that if you ask
a Yupno person about the past, they will gesture downhill
towards the mouth of the river, which is so integral to their way of life; and if you ask them about the future, they will gesture uphill towards the peak of the mountain,
and the source of their local river. And again, this remains the same
wherever they are in the landscape and even how far away they are
from their local river. So for the Yupno, time itself and the flow of time
is represented by the flow of their river. So what implications
does this have for synesthesia? Western time-space synesthete's forms,
as you've seen before, look a lot like clocks or calendars; they usually run in clockwise
or calendrical format around a circle. But what might these forms look like
for time-space synesthetes growing up among the Yupno
or among the Aymara in a world without access
to Western technology? Well, the simple answer is we don't know, since synesthesia studies
have overwhelmingly focused on the experiences
of Western university students like me, but we can look at other types
of synesthesia for clues. So there's a variation
of time-space synesthesia, which is called
sequence-based synesthesia, and it looks a bit like this. So people with the
sequence-based synesthesia, instead of seeing time, they see strings of numbers
as having forms and shapes. So this is a typical number form
of someone with this type of synesthesia. And in our modern age in the West, the twists and the breaks
that we see in these synthetic forms, they always happen in intervals of 10 - so 10, 20, 30, 40 - and this represents the fact that in the West, we all live
under a very pervasive decimal culture. Everything is in decimals. But this hasn't always been the case,
not even in the UK. So 150 years ago, Victorian statistician
Francis Galton was doing his research, and luckily for us, he was also recording examples
of sequence-space synesthesia. And this is a form that he recorded
in 1881 from a British person. And at first glance, this form might look pretty similar
to the one I just showed you, and in fact, it has a long stretch
here across the middle, which has numbers ordered
in decimal order. But what's interesting here
is where the breaks lie. And we can see that the breaks
lie on one side at 12, and then at the other side,
at 112 and 120, and this reflects the fact
that in Victorian Britain, the dominant numerical system
was the duodecimal system. And what I also love about this form is that you can see
a perfectly reproduced clock face just here on the right. I think it's great. But the point is that as culture changes,
so does synesthesia. So it's conceivable, even probable, that people growing up
in a culture without Western influence would display a completely different
time-space synesthetic form to those that we see today
in our research, perhaps even one
that doesn't focus on the body but one that focuses on the landscape, which as far as we know,
has never been seen. And the likelihood is that in focusing all of our attention
on Western accounts of synesthesia, we're missing out
on an extraordinary range of cultural and synesthetic variation that is only paralleled by the extraordinary range
of humans on this planet. So, beyond being, I think,
quite interesting, why is any of this important? Well, getting to grips with this idea of a synesthetic continuum
and its amazing variety could help us to better grasp how different areas of the brain
develop and work together. Research into brain connectivity
has helped us understand so much, from sleep to addiction to memory, but we still have a lot further to go. And I think that launching
a dedicated expedition to the furthest lengths
of this synthetic continuum could help us reveal vital information about the remaining mysteries
of cognitive function. For example, synesthesia reveals unexpected connections
between different areas of the brain, so it could easily be used to help understand
how cognitive decline works and maybe to even prevent it, or to help patients recover
from traumatic brain injury. And moving beyond science to society, I believe that truly understanding
how cultural differences can shape this tangible reality
that we see around us, even shaping time itself, can really help us get to grips with the concept of seeing the world
from other people's points of view. If we can begin by dispensing with this outdated idea
that we have rigid sensory borders and instead, come to accept
that we all sit somewhere together yet at separate points
on a continuum of experience, then perhaps we can take one step closer towards dispensing with unnecessary
social divisions altogether. And maybe that might even mean
one step further towards inhabiting a world that is extraordinarily
and joyfully unbound. Thank you. (Applause) (Cheers)
