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  • >> Thalia Wheatley: Over the course of millions of years,

  • the human brain evolved to solve certain problems.

  • And you might not have realized this,

  • but one of the biggest problems we evolved to solve is how

  • to detect the mind in our environment.

  • Because minds more than anything else affect our daily life,

  • our well-being.

  • Minds think.

  • Minds feel.

  • Mind act and interact with us.

  • They're our friends, our families,

  • our mates, our enemies.

  • And yet, mind are also invisible.

  • So how do we detect another mind?

  • Well, this is a question that my research aims to solve.

  • And we do so, of course,

  • by using visible cues, cues such as motion.

  • And even in the absence of human form,

  • we can detect the contents of another mind.

  • This log for example, is proud [laughing].

  • And we can do so also in sound, in tone of voice, even in music.

  • [ Piano playing ]

  • There we go.

  • There he is.

  • [ Piano ]

  • Oh [laughing].

  • Perhaps the most reliable, the most salient icon

  • of another mind is this: the face.

  • And even as its root word suggests,

  • the face is simply a facade, a facade of another mind.

  • And it's faces as the icons of minds that are so important

  • to us, that we become hardwired to detect them.

  • Right from birth, we find them captivating.

  • A newborn for example, will track two dots and a line

  • in the configuration of a face but only when it's

  • in the configuration of a face.

  • They won't track something that looks like this.

  • And this fascination with faces extends throughout the

  • life span.

  • What I'm going to show you here is a commercial

  • from this year's Super Bowl.

  • And the red blobs indicate where people were looking

  • when they're viewing the commercial.

  • [ Commercial playing ]

  • What you can see is that people spend all their time gazing

  • at the faces on the screen, even the face of a doll.

  • And faces are so important to us

  • that we actually have a visual strategy.

  • We err on the side of detection.

  • When in doubt, see a face.

  • And this is exactly the reason why we see faces everywhere.

  • We see faces, for example, in clouds.

  • We see faces in buildings.

  • We see faces in parking meters [laughing].

  • We even see faces in grilled cheese sandwiches [laughing].

  • And science has discovered the way our brain does this,

  • the way a brain detects our face,

  • by looking at our electrical activity.

  • Whenever we see something, millions of neurons fire

  • in our brain, causing electrical activity.

  • And this activity can be measured

  • by putting electrodes on the scalp.

  • And science has found, for example, that this is the kind

  • of electrical response you see

  • when you see an object such as a clock.

  • And keep this in mind because now I'm going

  • to show you what the electrical response looks

  • like when we see a face.

  • It's much higher.

  • And this is a doll face, and here is a human face.

  • Now, this can't be the entire story, right,

  • because we do discriminate between dolls and humans.

  • If we didn't, we'd wander home with people like this, right?

  • We'd started to converse with mannequins.

  • And of course we don't.

  • We don't just seek a face.

  • We seek a mental connection.

  • We look to see if the lights are on in someone's home.

  • So how does the brain do this?

  • Well, it turns out that,

  • if you give the brain a couple hundred more milliseconds,

  • it does it quite well.

  • The green line is the human face that sustains our attention

  • over time, whereas the doll face drops off

  • to the level of clocks.

  • And if you give the brain this extra couple hundred

  • milliseconds, it does a very good job at detecting a mind,

  • so good, in fact, that if I looked at pairs of faces --

  • here's a doll face, an inanimate face on the left

  • and a real human face on the right.

  • And if I made an artificial continuum of these faces

  • and I asked you very simply where does the face come alive,

  • you can do it; and you can do it consistently.

  • Here, for example, is a movie.

  • And I want you -- it's going to start as a doll face,

  • and it's going to turn into a human face.

  • And I want you to think

  • about where you think it becomes alive.

  • [ Pause ]

  • And now we can do this one together.

  • What I want you to do is raise your hand

  • when this doll face becomes truly alive, okay?

  • I want you to raise your hand

  • when you think it becomes truly alive.

  • [ Pause ]

  • Okay. So what I saw was the majority of you put

  • up your hands when the face was closer to the human endpoint

  • than it was to the doll endpoint.

  • And we see this many, many times.

  • In fact, this is about the average place

  • where people put the break.

  • And it doesn't matter if you ask the question,

  • When does the face become alive, or, When does the face seem

  • to have a mind, or, When does the face look

  • like it could experience pain, or, When does the face look

  • like it could formulate a plan.

  • The break is always the same spot.

  • What this tells us is imputing a physical life is tantamount

  • to imputing a mental life; that is, thoughts

  • and feelings only happen in the context of another mind.

  • So this is a critical tipping point because as soon

  • as we see a face is alive we imbue it with all kinds

  • of possible mental states.

  • So where does this tipping point, this critical decision

  • of seeing a mind and a face happen in the brain?

  • Well, to answer that question, we showed these kinds of faces

  • to people as they lay in this, an FMRI scanner,

  • which is simply really a very expensive

  • and sophisticated camera that takes pictures

  • of your brain and, importantly, takes pictures of oxygen levels

  • so that we can tell if parts

  • of your brain are active during what tasks.

  • Because neurons, when they fire, they eat up oxygen.

  • So the fluctuating levels show us what parts

  • of the brain are active when you see different kinds

  • of things, things like faces.

  • And these faces are particularly interesting to us

  • because you can group them in a couple of different ways.

  • You can think about them, for example, in terms of form.

  • The human face and the doll face look very similar,

  • and the real dog face and the stuffed dog face also look

  • very similar.

  • But you can also think about these faces

  • in a completely different way.

  • You can say, well, which faces come with a mind attached?

  • And that is the human face and the real dog face;

  • those faces are alive with minds,

  • and the toys are not alive.

  • So what did we find?

  • Well, here is the picture of this skull.

  • To orient you, the eyes are on the right and you see the bridge

  • of the nose and the ears on the left.

  • And if you shave off a part of this skull, you see this area

  • of activation in visual cortex, way back in the brain.

  • And this area of activation really likes

  • to group faces based on form.

  • So it activates this particular pattern for human

  • and doll faces -- it's very similar --

  • and another pattern for dogs and stuffed dogs.

  • We think that this part of the brain is the source

  • of this response I showed you earlier, the response

  • that is indiscriminate.

  • Any face will do.

  • But this can't be the whole story, of course.

  • And if you get out of visual cortex, you'll start

  • to see that, as you move forward in the brain, the brain starts

  • to do something completely different.

  • It starts to process faces in terms of a mind.

  • We think that this response is related

  • to the sustained attention to human faces in particular.

  • And, indeed, most of the brain cares only

  • about human faces, human minds.

  • Areas such as frontal cortex.

  • And, in fact, all over the brain you see this pattern.

  • You see parts of the brain involved in social

  • and emotional understanding and empathy and perspective taking.

  • So what I've showed you so far is that we are experts

  • in detecting a mind in a face and where that is in the brain.

  • But what I haven't told you yet is how do we do it.

  • How do we glean mind from a face?

  • To answer this question, we went back to the morphs;

  • and we showed people just a little part of them.

  • We showed them either the nose, the mouth,

  • the eye, or a patch of skin.

  • And we asked, just given this little piece of information,

  • can people tell, is it alive?

  • Is this patch of skin, was it from a doll;

  • or was it from a human face?

  • And it turns out that a patch of skin ask hopeless.

  • We have no idea if the skin is

  • from a living thing or nonliving thing.

  • A nose fares no better.

  • A mouth is a little better but still not very good.

  • Give people an eye, and the task is effortless.

  • People can detect whether the lights are

  • on in someone's home in an eye.

  • They don't need the entire face.

  • So this suggests that the age-old aphorism is correct,

  • that eyes truly are the windows to the soul.

  • They are the portals to another mind.

  • And you might have already realized this

  • if you've ever seen a CGI movie.

  • CGI stands for computer graphics imagery,

  • and a CGI movie you might have seen is Polar Express.

  • Now, Polar Express was a technological achievement.

  • It took motion capture sensors on Tom Hanks,

  • extracted his motion, put it on the animation of a conductor.

  • But the movie fell short.

  • It was widely panned as having characters

  • that were flat and lifeless.

  • Something was not quite right with them.

  • And so what they did for Beowulf is they put a lot more sensors

  • on the face and other parts of the body to try

  • to make the characters more lifelike, more realistic.

  • And this is what a New York Times critic said about Beowulf:

  • Although the human face and especially the eyes

  • in Beowulf look somewhat less creepy than they did

  • in the Polar Express, they still have neither the spark

  • of true life nor that of an artist's unfettered imagination.

  • You see the cladding but not the soul.

  • This begs an interesting question because it suggests

  • that there might be a chicken and egg thing going on here.

  • For example, did the human brain always have the ability

  • to detect another mind, or is this a recent development

  • in response to all these sort of human imposters in our midst?

  • That is, have we recently developed the ability

  • to see mind in a face because we're surrounded

  • by synthetic faces.

  • We have a world that is populated by things

  • like this: mannequins.

  • We go to the movies.

  • We see animations.

  • We play video games with avatars.

  • So to answer this question whether this is a fundamental

  • and ancient property of human brains or a recent development,

  • we went somewhere that they don't have these things.

  • We flew halfway around the world from Hanover, New Hampshire,

  • to BanLung, Cambodia, to this tribe,

  • a remote hill tribe of Luoc [phonetic].

  • And we set up in a hut, and we spread out the morphs

  • on the floor, eleven morphed images

  • from a human face to a doll face.

  • And we asked them very simply to break the faces in terms

  • of where they become alive.