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[Music]
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[Applause]
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[Music]
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this amazing object is a human
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brain I don't have one here to show you
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but um if I could get you to imagine
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holding one in your own hands um you'd
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have an object in your hands that is
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roughly 1.4 kilos of fat water protein
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carbohydrates and salt that's
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it but everything that we
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are all of our personality everything
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exists in this wondrous
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object and this wondrous object is
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contained within our
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skulls in our skulls our brains are
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basically in Black boxes and they know
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nothing about the world World outside
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unless it's informed by the senses that
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plug into the
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brain there are 12 cranial nerves in in
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the brain and all of our senses plus
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some end up flowing into our brains to
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to help us synthesize our
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reality the trick is every one of us
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perceives the world a little bit
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differently but we don't know it unless
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we given the opportunity to compare what
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we think we know about the world with
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what others think they know about the
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world
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neuroscientists um now recognize a
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broader range of sensory experiences um
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beyond the five basic human senses um
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with at least 20 senses that have
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evolved uh throughout
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Evolution we rely on all of these 20
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senses as a sophistic ated Network to
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literally help us synthesize our reality
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Moment by
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moment when there are
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gaps in the streaming of sensory
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information into our brains our
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brains will make up the difference they
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will they will model or predict what our
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brains think about reality almost like
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we're along for the
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ride this modeling um basically is our
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reality but it's also the foundation of
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Illusion and
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misunderstanding my scientific career
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has been uh the study of just one of
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these senses uh
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Vision vision is the sense that a lot of
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us use to inform what we think we know
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about
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reality I'm a neuroscientist who studies
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uh a small piece of the brain called the
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retina at the backs of our our eyes the
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goal of my work is to understand how
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retinal neurons are wired together
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forming circuits and how those circuits
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break in diseases that Rob us a vision
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like retinitis Pigmentosa age related
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macul degeneration and
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glaucoma these are diseases that may be
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affecting some of us in this room right
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now um certainly as we grow older uh
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about 20% of us will suffer from at
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least one of these
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diseases when we develop in utero our
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eyeballs come off as stocks from our
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brains and start forming um all the
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components of of of our vision of our
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eyeballs uh what we have here is a
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cartoon of of an eyeball with the cornea
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at the front of the eye that's the the
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clear transparent object this is where
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surgeons operate on when they do vision
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correction
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surgery after that comes the lens the
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lens is what gets replaced when we have
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cataracts right in blue around the lens
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is is the
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iris um the iris uh gives us the color
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of our eyes blue green or or
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brown and in back in
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pink is the retina and the optic
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nerve the retina is not normally pink
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the retina is
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normally thin
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transparent uh like wet TI tissue paper
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lining the back of the eye but this wet
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tissue paper um belies this wet tissue
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paper looking thing belies its
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complexity right so the retina is
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actually a sophisticated Computing
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device with image detecting at the back
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of the retina with retinal neurons in
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front that have circuitry and all that
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circuitry calculates everything that we
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know uh as the first parts of
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vision the ancient Greeks
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thought that Vision came from within the
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eyes that that we broadcast the world
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out through our eyes into what we could
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see kind of like virtual
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reality we know now that that's not
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correct we know that photons come into
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the eye and land on Photo receptors at
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the backs of our eyes and that's how we
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start communicating Vision calculating
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Vision it turns out that this thing that
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we call vision is complicated um even
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for those of us who study vision
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and the
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more we look the deeper we look the more
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complex vision gets but one of the
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things I love about studying vision is
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that it reveals how different we all
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are each one of us sees the world a
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little differently and in vision
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we can effectively communicate this U
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with a couple of uh exercises
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here this is a photograph um made by a
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friend of mine David hobby uh on a trip
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that a group of friends uh made to
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Cuba and I'll use it to show a few
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examples of what I mean by our sensory
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paradigms can be different and thus our
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realities can be different because our
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senses are
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filters that help us create our
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realities many of us synthesize in our
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brains a different reality based upon
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differences in our visual systems right
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and again the convenient thing about
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vision is that we can easily demonstrate
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this right so some of us have very good
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vision and we see the world in 2020 very
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sharp some of us are myopic meaning that
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we see well up close but we don't see so
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well far away but thankfully we've got
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an old technology
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glasses that can help us see
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well these glasses help us all live in
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the same shared
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reality but some of
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us upwards of 8% of Mal specifically are
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color
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blind this animation shows what the
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world looks like to people with the two
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most common kinds of color blindness
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protopia and deuteron
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Opia so color blind people see color
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just not in the same way that people see
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color with three
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colors they see just fine but their
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retinal biology renders a reality that
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confuses red and green or blue and
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yellow right and there's good evidence
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that suggests that there are some
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genetic females that see the world in
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four
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colors they see a slightly richer world
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than those of us who see the world in
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three
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colors and if you think that's
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cool there are organisms like turtles
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Right common turtles that see the world
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World in nominally seven
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colors they see a a richness of color
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that we can't even imagine in our
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heads so most of the
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time people who see the world in three
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colors agree on what reality is with
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people that see the world in two colors
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with the possible exception of some
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confusion about certain
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colors and in fact
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a lot of the times people who are
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colorblind don't even know that they're
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colorblind until an opportunity comes
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along or a challenge comes along that
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illustrates to them how their reality is
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fundamentally different from somebody
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who sees the world in three
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colors and judging from the size of this
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audience there's
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probably 30 people in this room who are
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color
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blind most of the time each of our
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brains tends to agree with other brains
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on what reality is um and this again is
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based upon our shared understanding of
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the world through our
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senses do you remember this from back in
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2015 sometimes an event comes along like
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the dress right and the
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dress was this
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revealed this fundamental Rift in how
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people see the world and and really new
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and surprising
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ways for vision scientists particularly
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Vision scientists that study color
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perception the dress was a
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phenomenon right it was like this Mass
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experiment that allowed us to to get
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some insight into how people view the
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world so let's let's do a little
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experiment um can we get the house
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lights up a little bit is that possible
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awesome all right almost half the world
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sees the dress as blue and
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black the other half of the world sees
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it as white and gold with about 10% of
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people that see it as blue and
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brown so can we have a show of hands how
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many people in the room see the dress as
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blue and black back raise your
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hands this is fun okay put your hands
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down how many people in the room see the
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dresses white and
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gold
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yeah all right how many people in the
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room see the dresses blue and
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brown
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this is awesome right and and and and
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this this tickles me because this worked
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um
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[Music]
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the the reason that this is
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cool is there are almost a thousand
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people in this
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room and we are all experiencing three
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completely
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different realities at the same
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time it turns out how we see the dress
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is based upon our perceptions of color
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and and prior experience and what we
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expect color to be that's the simplest
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explanation but the other really really
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cool thing about this
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experiment is the degree of certainty
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that people have about what color they
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see the dress as and there's very little
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confusion on this right people see the
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dress how they see it and that is their
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reality here's where I get to say
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something
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controversial and it's only
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controversial because of these really
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strongly held beliefs that we have about
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what we think reality
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is we think about color as being
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intrinsic to the
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universe that everything in the universe
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has some sort of color to
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it but the truth is there is no color in
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the
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world let me repeat
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that there is no color in the
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world
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photons the things that
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um fly into our eyes and trigger photo
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receptors at the backs of our retinas
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have no
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color color is an
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illusion that socially culturally and as
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a species we
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share it's a shared
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illusion it's wild
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right how do you explain to somebody
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what color the sky
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is you say it's
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blue but what's
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blue you could you could give me a
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technical explanation for the wavelength
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of blue and you could talk about
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luminance and you could talk about
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Hue but what's
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blue imagine trying to explain what blue
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is to somebody who's been blind from
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birth it can be a daunting task right to
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to describe something so fundamental to
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our understanding of
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reality this shared
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illusion uh is created by the biology of
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neurons in our retinas and in our
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brains and these neurons have evolved to
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interpret electromagnetic energy from
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this gtype main sequence
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star known as a yellow dwarf that is our
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sun our
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sun
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defines what we call Vision through the
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energy that it gives off
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and this energy is is basically the
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architect of what we think color
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is so this is a movie created by NASA's
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Solar Dynamics Observatory um and and I
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show this to give some idea of the kinds
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of energy that are generated by Fusion
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uh in in the sun right some of that
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energy is released as heat uh at that
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makes life possible on Earth some of
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that energy is released as photons that
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fly through space and land on Earth and
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have influenced
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Evolution so what do I mean by there is
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no
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color our neural
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systems fundamentally operate by
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comparing Things We compare senses
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Through Time We compare senses against
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one
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another um and our brains are constantly
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comparing these inputs against one
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another and comparing
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them prior experience is important with
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this but novel input is also integrated
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into these models of what we think the
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world looks
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like so what we think of as color is
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created by our brain's
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interpretation of the
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electromagnetic emissions from the Sun
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specifically the wavelength of
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photons so it turns out that this
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rainbow that we see is red green blue
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and all the colors in between is is sort
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of like a goldilock zone right it's it's
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it's a perfect sort of zone for vision
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wavelengths on the left side of the
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rainbow over here radio microwave and
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infrared are too low energy or they
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generate heat in tissues wavelength LS
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on the right side of the rainbow
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ultraviolet X-ray and gamma rays are two
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high energy right they break chemical
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bonds in our
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tissues but wavelengths in the middle
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are just right for the photo receptors
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in our
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eyes so we've known since
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1872 uh an experiments by James Clark
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Maxwell
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that photo receptors respond only to
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those photons that match
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wavelengths in a molecule in photo
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receptors called
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opson and it turns out within this range
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of light from 400 to 700 ners there
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corresponds a set of options in photo
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receptors in our retina that match what
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we perceive as blue light at 42 NM green
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light at 534 NM and red light at 564 NM
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with a Peak at 500 n for the rods which
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are low light sensitivity photo
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receptors that encode no
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color
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so our eyes evolve to be light capturing
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devices and the photo receptors in our
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retinas have evolved to basically be
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biological
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antennas for Photon energies between 400
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and 700
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nanm our brains perceive these
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differences in weighting between
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wavelengths as
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colors but the colors don't exist in
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nature what we perceive are basically
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combinations of wavelengths that we
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associate with things that are important
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to us these these are things that are
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important for our survival their food
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their their sources for
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reproduction so I'm going to leave you
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today with the idea that we've talked
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about color and we've talked about
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vision and how each of us lives in
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slightly different
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realities but we all live on
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continuums uh in all of our 20 senses or
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more senses some of us have deficits in
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these senses that influence how we
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perceive the world others of
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us have different ways of processing the
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information from these senses that are
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different from the people around us and
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that renders a different reality for us
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in other words we all perceive and
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process the world a little differently
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from one another but we generally agree
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on what reality
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is so as our world gets more chaotic and
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divisive I I I would like to encourage
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you to sort of recognize this uh and
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default to compassion and kindness by
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recognizing in everyone around us the
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richness of the diversity of our
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experiences thank
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[Applause]
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[Music]
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you