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  • [Michael breathing heavily]

  • [laughing nervously]

  • Everyone is scared of something.

  • But is there some thing

  • that everyone is scared of?

  • What is the scariest thing possible?

  • [Michael] So what is the scariest thing?

  • - Is it thunder? - [thunder crackles]

  • Shadows?

  • Being burned alive?

  • [laughs nervously]

  • [laughs evilly]

  • No. It's also not heights or needles,

  • snakes, spiders, sharks--

  • those things can be scary to some, sure,

  • but not to all.

  • So here's what I mean by "scariest."

  • I want a thing-- an object, an action, an idea--

  • that, at my disposal, would be guaranteed to elicit fear and panic

  • in anyone who might happen to walk into this room right now,

  • regardless of how old they were, their cultural background,

  • their abilities, or even their neurology.

  • An adventure towards this ultimate terrible thing

  • must necessarily focus on the womb.

  • No, not the kind you came from,

  • but the womb in which fear itself gestates: the mind.

  • -[wind whistling] -[thunder crashes]

  • To find the scariest thing,

  • we must understand how fears are born.

  • [thunder crashes]

  • [projector whirring]

  • Where are we going?

  • [laughs evilly] Don't worry about it.

  • Only two things matter:

  • one, I've got plenty of gas, so what could go wrong?

  • And two, our destination is a little bit spooky

  • and we're gonna learn.

  • Because in order to truly grasp

  • what makes the one true scariest thing,

  • well, we need to dive deeper into how we learn fears.

  • [monster growling]

  • [Michael] To start out, I commissioned

  • a fear-conditioning demonstration on me.

  • You've probably heard that exposure therapy

  • can help people overcome their fears.

  • Well, the same principles can be used to create fears.

  • Hello, Michael? I'm Dr. Tomislav Zbozinek from Caltech,

  • and today we're gonna do some fear conditioning.

  • Do you have any heart conditions

  • or any serious major medical conditions?

  • - No. - Okay.

  • You've done this to people before.

  • - Hundreds of times. - And they were all okay?

  • They were all okay. Yeah, everything worked out okay.

  • - All right, I'm ready. - Okay, perfect.

  • [Michael] The protocol for fear conditioning

  • involves my being electrically shocked and startled

  • by the sound of a human scream

  • in connection to visuals I see on a screen.

  • Bioelectric sensors

  • monitor my body's physiological reactions.

  • For example, my perspiration, an indirect measure of fear

  • that you can't consciously control.

  • Is this how you run this at Caltech?

  • - Yes, this is the exact-- - [laughs] Exactly the same way.

  • - Minus the restraints, of course. - Oh, the-- Oh, okay.

  • Yeah. Everything else is solid fear conditioning--

  • - As your usual--? - Yes. Absolutely.

  • All right, I'm game. Let's help science.

  • [Michael] The goal of this procedure

  • is to condition me to be scared of something

  • I've never feared before--

  • a mundane, harmless geometric shape--

  • something normal people don't find threatening at all.

  • - [electricity crackles, recorded scream] - Aaaah!

  • -[electricity crackles] -[recorded scream]

  • Little bit more scared of the square right now.

  • -[electricity crackles] -[recorded scream]

  • [Michael] A clear pattern emerges.

  • My senses are being assaulted

  • only when the purple square is onscreen.

  • -[electricity crackles] -[recorded scream]

  • [breathing heavily]

  • But am I actually being conditioned

  • to fear a purple square?

  • -[electricity crackles] -[recorded scream]

  • All right, Michael, you're all done.

  • - Hoo! - How was it?

  • Well, it felt like I was one of Pavlov's dogs.

  • I couldn't help what I was doing,

  • and I was being trained to do it in response to something,

  • and that something was

  • an otherwise very unassuming geometric shape.

  • Exactly. With Pavlov's dogs, he had a bell and food, something positive at the end.

  • But in fear conditioning, we have something aversive and negative at the end.

  • [Michael] And it worked.

  • Once my brain associated the purple square

  • with being shocked,

  • my physiological response to the square

  • went up and stayed up.

  • The mere appearance of a simple geometric shape

  • made me scared enough to break a sweat.

  • The results show that you physiologically really ramped up

  • to that purple square, specifically.

  • You quickly learned to be afraid on a physical level.

  • You showed fear.

  • I came in here today normal old Michael,

  • but I'm leaving as a brand-new Michael

  • who is afraid of purple squares.

  • The human brain can learn to be afraid of almost anything.

  • [Michael] To better understand how this works,

  • we need to look at what's going on neurologically.

  • What happens in the brain during fear conditioning?

  • Well, what we know is that over evolution,

  • over millions of years,

  • we've developed these defensive circuits in our brain.

  • And the amygdala sits on the front of the memory systems

  • of the hippocampus.

  • And the amygdala seems to play an important role

  • in determining what the danger is

  • of something in the world.

  • It tells us what we should be remembering,

  • what we should be learning, that is important to survival.

  • [Michael] Our brain actually has two amygdalae--

  • one in each hemisphere.

  • The function of the amygdalae

  • is at the center of fear research,

  • which covers human behavior ranging from the risk averse...

  • to high risk-takers

  • like free soloist Alex Honnold.

  • Ancient humans who avoided danger

  • and survived long enough to reproduce

  • became our ancestors.

  • They populated the world with creatures like us,

  • organisms that instinctively avoid and are averse to

  • potentially dangerous sensations.

  • Things like pain and being sick,

  • suffocation-- the need to breathe.

  • We don't think those feel good,

  • and you don't have to learn to not like them.

  • Even a newborn is distressed by them,

  • which makes them "innate aversions."

  • Fear is the anticipation of these innate aversions.

  • When the purple square was paired with electric shocks,

  • my amygdala quickly made that association

  • and began consciously and unconsciously

  • arousing fear in me whenever I saw it.

  • For this reason, I want us to think of sensations as flies

  • and our amygdala as a meaty little spider

  • spinning a web of fear.

  • [thunder crackling]

  • [Michael] The web is pre-stocked with our innate aversions.

  • Whenever an experience is associated with an innate aversion,

  • it's like a fly landing on the web.

  • This alerts the amygdala spider,

  • which weaves a powerful connection

  • between that experience and the innate aversion

  • it's associated with.

  • In my case, that innate aversion was pain.

  • which probably isn't the scariest thing for everyone,

  • because, well, some people have a high pain tolerance.

  • Others can learn to suppress their fear of pain.

  • And, of course, some people enjoy pain.

  • But the point is, now that new experience

  • will stay trapped in your web of fear,

  • a new member of the library of things that scare you.

  • To find the scariest thing, we must wander through

  • the darkest recesses of the web.

  • Everything caught in your web of fear

  • is somehow connected to death.

  • Avoiding it--surviving--

  • is, after all, what makes fear useful.

  • It's why we are still here today as a species.

  • So if death is at the very center of all of our webs of fear,

  • does that