<i> - When it comes to illusions,</i> <i> optical illusions
get all the attention.</i> But the whole body you have can be fooled
and can fool the brain. One of my favorite
physical illusions is the thermal grill illusion. and you can do it
right at home. I have some hot dog halves
in an ice bath. I also have warm
hot dog halves. Now what I'm going to do
is marry the halves together so that they alternate,
warm, cool. Warm, cool. When I'm done,
I will have a torture device. But not one that hurts
your body, one that hurts your mind.
[laughing] <i> [electronic music]</i> <i> ♪ ♪</i> Rosanna Pansino.
- Hello, Michael. - Welcome to "Mind Field."
- [chuckles] <i> - Rosanna Pansino is the host
of the YouTube cooking show</i> <i> "Nerdy Nummies."</i> - Brain cake.
Mmm. <i> - So I thought she would be
the perfect candidate</i> <i> to try out
our hot dog illusion.</i> - Oh, yeah. - Now you didn't hear or see
anything I just did, right? - No.
- Good, all right. Well, you are in
for a treat. What I want you to do is take
the bottom of your forearm and place it, skin showing...
- Okay. Right onto these hot dogs. - Oh! - What'd you feel?
- Ouch. But now touch them
individually. - Oh, like, hurt. Cold, warm, cold, warm,
cold, warm. - But none of them is as hot
as they all felt together. So what's going on?
- I don't know. Magic? What's going on over here?
- Can I try? Of course I can try.
It's my show. - Yeah, do it.
- Oh, yeah. What we've built here
is a version of the thermal grill illusion. And for reasons
that are still being debated, this can cause a sensation
of pain. Maybe the sensors we have,
specific to hot and cold, are both also specific
to extreme pain. And getting them to fire
right together makes the body think,
"Whoa, whoa, whoa." If they're both firing
that near to each other, that means get away.
- Red alert. - Red alert, yeah.
- That's what my arm did. - So what I'm really trying
to say is this is a great way
to hurt someone without there ever being a mark
or any actual damage. - That's pretty sneaky.
- Do try this at home. <i> [tranquil music]</i> <i> ♪</i> ♪ - The surface
of the human body contains millions
of nerve endings that send touch-related sensory
information to the brain. But in some cases,
those sensations don't even need to be generated
by nerve endings. Ever heard of sympathy pain? The most well-known type
of sympathy pain is called couvade syndrome. It's when
a pregnant woman's husband goes through labor pains. <i> Husbands can actually
sympathize</i> <i> with their pregnant wives
so much</i> <i> that they experience
the same problems,</i> <i> such as weight gain,
insomnia,</i> <i> nausea, mood swings,
et cetera.</i> Sympathy pain is also known
as synesthetic pain. It's pain sparked by seeing
someone else get hurt. - Ooh! <i> - Amputees can actually
be more susceptible to it</i> <i>because experiencing trauma can
make the brain more sensitive</i> <i> to other people's pain.</i> <i> Amputees can also feel pain
in the limb</i> <i> that is no longer there.</i> That is known
as phantom pain. <i> But perhaps
the most surprising way</i> <i> that the brain and pain
interact</i> <i> can be demonstrated
by the nocebo effect.</i> <i> Have you ever heard
of the placebo effect?</i> <i> It's like when
a fake pain pill</i> <i> actually cures
a person's pain</i> <i> because they have a positive
expectation it will work.</i> <i> Well, today,</i> <i> we're demonstrating
the exact opposite.</i> <i> If a subject expects</i> <i> they're going to experience
something unpleasant,</i> <i> like pain,
will they feel it</i> <i> even if it actually exists
only in their mind.</i> <i> We've told our subject that
she's participating in a study</i> <i> to test a non-invasive
bone density scanner.</i> <i> But actually,
it's a totally fake machine</i> <i>that we built from a desk lamp,
an air compressor,</i> <i> and the kind
of $10 laser pointer</i> <i> you might tease your cat with.</i> <i>It doesn't cause physical pain,
or for that matter,</i> <i> physical sensation
of any kind.</i> It doesn't hurt at all.
You guys, this doesn't work. [laughter] <i> But will the expectation
alone</i> <i> make our subject think
she's feeling real pain?</i> - So come on in here. Just go ahead
and take a seat right there. And then when you feel
ready to drive, just let us know
and we'll dismiss you, okay? - Okay. Thank you. <i> - First, we have to make
our subject</i> <i> expect to experience pain.</i> <i> And to do that, our actors are
going to scare her a little.</i> <i> Sorry, Jessica,
this is for science.</i> - So are you already done? - Yeah. I just, you know,
need a minute. Then I'll be good to go.
- What'd you do? - It's like a targeted laser. It tests bone density. - Did it hurt?
- Yeah. <i> - By the look on her face,</i> <i>it appears we have successfully
primed our subject</i> <i> for what's to come.</i> - Okay, Jessica,
we're ready for you. <i> - The question is,
when put to the test,</i> <i> will she actually feel pain</i> <i> when there is really
none there.</i> - This is Jessica.
- Hi. - Hi, Jessica.
Come on in. Won't you have a seat? <i> - Everything in this room,</i> <i> the medical equipment,
the hospital supplies,</i> <i> even the demeanor
of our fake nurse,</i> <i> is designed to play
on Jessica's mind.</i> <i> To psychologically induce
the anticipation of pain.</i> We're testing out some
equipment. It's not invasive.
We need to measure the side effects
and patient reaction. And I want you to be
really descriptive about what you're feeling. And pay close attention
to the pain that you feel and how it grows. <i> Notice how we are suggesting
that she will feel pain,</i> <i> further raising
her expectations.</i> - I'm gonna give you
a ball to squeeze for pain management, okay?
- Okay. - And any time you want to stop,
it stops right away. - Okay.
- Okay? - You ready? [machine humming] - It's definitely warm.
- Uh-huh. And, like, like, tingly. <i> - After only about seven
seconds,</i> <i> she's already feeling a
physical sensation on her skin,</i> <i> where there is none.</i> <i> Keep in mind, we tested
our fake bone scanner,</i> <i> and the light emits zero heat
or feeling of any kind.</i> - Yeah, now it's--
doesn't feel that great. - You want me to turn it off?
- No, it's okay. - We're at 30 seconds.
- Really, like, stinging. - A sting?
- A sting and, like, really, really hot.
- Now it's hot. We're at 45 seconds.
- Yeah, it doesn't--it's... - Okay, I'm gonna turn it off.
- Okay, thanks. - You described warm
turning to hot. - It was, like, warm
and then that, like, heat grew into more of, like,
a sting. - On this pain scale,
could you point to the amount of pain
you were feeling? - Between a six and a seven. <i> - According to the pain
assessment scale,</i> <i> she experienced
significant pain.</i> This is completely up to you,
but we can move to level two, which is slightly
more intense. - How many more levels
are there? - Uh, there's just five. - There's five levels?
- There are five. - Oh, my gosh.
- But again, you're in the driver's seat. - Uh, yeah, sure. Let's do it.
[chuckles] <i> - Here's another test
of our nocebo.</i> <i> Will she feel an increase
in her level of pain</i> <i> if she expects to?</i>
- You ready? - Mm-hmm.
[machine humming] <i> - Keep in mind,
level two is fake.</i> <i> We're not doing anything
different than before,</i> <i> meaning nothing
is happening to her.</i> - So, yeah, it started off
higher than the last time,
I think. It's definitely, like,
already stinging. <i> - Immediately, she reports
increased pain on level two.</i> It's 15 seconds. - It feels really, really,
really hot and, like, penetrating. - How deep?
- Um... - 30 seconds.
- I don't know, like, 1/2 and inch or, like,
an inch. Yeah, it is...
it's very hot. Um, like burning. Like my whole arm is, like,
on fire. - We can stop at any time.
- You want to call it? - Yeah.
- Okay, we're off. - Do you need a tissue?
- Yeah, thank you. - You're welcome.
- [sniffs] - Could you rank for me
how you felt at level two? - Like 9 1/2. <i> - The power of suggestion
was so strong,</i> <i> our nocebo caused our subject
to think</i> <i> she felt almost the worst pain
imaginable.</i> <i> Other subject felt different
imaginary sensations.</i> - The muscles are kind of, uh, kind of burning
a little bit. - Stop.
- How did that feel? - That was, like, a seven. Actually it's tingling
a lot more now than it was before. <i> - I was surprised
at the intense reaction</i> <i> some subjects had to a feeling
that was created</i> <i> only in their minds.</i> - Look, I'm gonna stop it now.
That was 45 seconds. Describe for me the sensations
that you were having. - It felt like
a little prickle like when you get
goose bumps. <i> - What about our original
subject</i> <i> who experienced a severe
9 1/2 on the pain scale?</i> <i> How will she feel when she
learns it was all in her head?</i> I want to debrief you
on everything that we're up to today. So this is
a psychology program, and this equipment is not
doing anything to you. This is just a machine
that makes noise. And that's just a laser pointer
on a lamp. - For real?
- For real. - Oh, my God. [laughing]
- You were never in danger. - We didn't do anything to you.
- Oh, my God. - This is an investigation
in pain anticipation. - Yeah, that worked.
- I was so scared. [laughing] I was so close to, like,
going to, like, just say, "You know what?
I changed my mind." I was so close to leaving. - You did say that you felt
a prickle. - Uh-huh.
- How do you feel about that? - Whether it was really
I did get goose bumps or I was nervous,
which is why I felt it. I know, as a person, like, if I think there's going
to be pain, I'm gonna feel something. - I do still feel, like,
kind of like a burning sensation
on my arms. - Really?
- Yeah. <i> - The power of suggestion
is so strong</i> <i> that this subject continued to
imagine a physical sensation,</i> <i> even after learning
it wasn't real.</i> The name for the effect
is the nocebo effect. It's a negative effect caused
by nothing but the mind. - It makes perfect sense,
you know, the power of suggestion. I'm shaky just thinking
about it. - Pain and touch are weird. But what about when touch
straddles the line between pleasure and pain? When a sensation
makes you laugh and drives you crazy. I'm talking about tickling. <i> Part of what makes you laugh
when you're tickled</i> <i> is the element of surprise.</i> <i> Your brain doesn't know
exactly what to expect</i> <i> or when it's going to happen.</i> <i> On the other hand,
it's impossible</i> <i> to tickle yourself.</i> <i> If the brain knows
where and when and how</i> <i> you are going to be touched,
you won't laugh.</i> But professors of cognitive
neuroscience at the University College
London have invented
the tickle machine. <i> Subjects sit in
the tickle machine</i> <i> with their feet against
a brush</i> <i> that is connected
to a handle.</i> <i> At first, when the subjects
turn the handle,</i> <i> the brush rotates
at the exact same time</i> <i> resulting in no tickling.</i> <i> Then the machine is switched
into tickle mode...</i> - [laughing] <i>
- Which causes a delay</i> <i> of less than a second
between when the subject</i> <i> turns the handle
and when the brush moves</i> <i> against their foot.</i> - [laughing]<i>
- This slight change</i> <i> is enough to prevent
the brain's cerebellum</i> <i> from predicting
the sensation,</i> <i> thus allowing the subject
to respond to the tickle.</i> - [laughing] - Tickles can be fun. Pain, not so much. If you couldn't feel pain,
that would be great, right? Or would it? Let's meet Steve Pete. Steve, I understand
you don't feel pain. - Yes, I was born
with a rare genetic condition called congenital insensitivity
to pain. It only affects about 40 to 50
of us around the world with it. - Only 40 or 50 people?
- Yeah. So far that we've been able
to find. - And tell me what it means when
you say you don't feel pain. - Pain is used
to detect injury and it kind of sends a signal
to your brain saying, "Hey, don't do this anymore."
It's an alarm system. So what happens
with my condition is we feel what's going on like if I were to touch
your shoulder, you would feel me
touching your shoulder, but if I were to touch
your shoulder in a way that's painful,
I would feel just a pressure, and the signal of pain
would not travel to my brain. - Okay, so you feel everything--
- Everything else. that I feel,
but you just don't feel pain. - Yeah. Correct.
- But that could be dangerous. How did you first find out
that you had this condition? - Well, what happened was
I was teething and I chewed
part of my tongue off. <i> So my parents quickly took me
to my pediatrician.</i> - Wow. Are you ticklish?
- Yes. - Do you itch?
- Yes. - Do you like massages?
- Yes. - Do you take painkillers?
- No. - What about a headache?
- No. - What about spicy peppers?
- I enjoy them, yeah. I mean, I do sense
the burning sensation, but nothing painful. - What about intestine pain
like gas pain? - That's something
I don't feel, so that kind of ties into
one of my biggest fears, which is having, like,
appendicitis or any other type
of internal damage that I just don't know about
until it's too late. - Is there an upside to this? I'm sure that people,
often naively, hear that you don't feel pain...
- Yeah. - And they think,
"Oh, man. Well, you should become
a boxer." - The only upside to it is,
uh, <i> being that I have had so many
injuries during my childhood,</i> <i> as I get older, I won't feel
the pain that comes with it.</i> <i> Other than that, really,</i> <i> I just try to live
my life normally</i> <i> as everyone else does.</i> - I cannot describe
pain to you. Just like you can't describe
a color to someone who's blind. - Which is where I run into
my problem with trying to describe
what not feeling pain is like. - Wow, I'll bet. Well, Steve,
thank you very much. This was really,
really fascinating. <i> So not being able to feel pain
is actually a bad thing.</i> But likewise, the anticipation
of pain can be bad too. Just making someone think
that they might be tortured soon could be a torture device. <i> The CIA and Guantanamo Bay
are known</i> <i> for using
psychological torture</i> <i> involving the anticipation
of pain</i> <i> against prisoners
in the war on terror.</i> The effects of this type
of torture can last a lifetime. So what's worse? Waiting for pain to happen
or the pain itself? You might be surprised. <i> We're basing our investigation</i> <i> on an anticipation of pain
experiment,</i> <i> conducted at the
University College London,</i> <i> which gave subject
two options.</i> <i> Option one: Experience
intense pain right away.</i> <i> Or option two: Anticipate
a lower level of pain</i> <i> in intervals
every few minutes.</i> <i> Researchers found that the
psychological effects of dread</i> <i> can often be worse
than the pain itself.</i> <i> We decided to demonstrate
the phenomenon</i> <i> by setting up
a fake research study.</i> We are looking into the effects of electrical
stimulation on the body. - Okay.
- It's all completely harmless. But it can be unpleasant.
- Right. - So we'll show you
the two settings, all right? I want to show you first what we
call the light setting, okay? - Okay.
- You ready? - I guess so. [buzzing]
Oh. - And then there's
the high setting. [buzzing]
- Ow. - Okay.
- I don't--[laughing] - All right, so again,
unpleasant definitely... - Yeah.
- But you're safe. We call this the low voltage
or light shock. - Okay.
- Ready? - All right. [buzzing]
Hmm, okay. - And now we'll show you the
high voltage or higher shock. - Oh, okay. [buzzing]
Ooh. - Okay.
- Okay. <i> - Now it's time
for our subjects</i> <i> to make an important choice.</i> All right, so now that you know
the two differences, you either can choose
choice A, which is one high voltage shock
every ten seconds for a minute. - Mm-hmm.<i>
- Will our subjects choose</i> <i> the higher,
more painful shocks,</i> <i> but get it over with
right away?</i> Or choice B
is one low voltage shock every ten minutes
for one hour. <i> Or will they choose
the lower shocks,</i> <i> but be forced to anticipate
the pain for ten minutes</i> <i> between shocks
for a solid hour?</i> Either way,
you will be here for an hour. <i> What's worse?
A higher level of pain?</i> <i> Or having to wait
and anticipate</i> <i> the lower level of pain?</i> - I'll take the long. - I think I'll do the shorter, uh, more painful one. - Okay. <i> Now that they've made
their choices,</i> <i> it's time to see how
our subjects</i> <i> experience these two options?</i> <i> The subject who chose
to anticipate</i> <i> the lower level of pain
during the course of an hour</i> <i> is seated in the low shock
administration room,</i> <i> along with our actors,</i> <i> who are pretending
to get shocked.</i> - Hi. <i> - This subject's hour-long
ordeal is just beginning.</i> <i> But what about the subject
who chose to get it over with</i> <i> and take the more painful
shocks right away?</i> - We're starting now. Here's shock number one.
[buzzing] - Ow!
- Okay. <i> - Yes, the shock is painful,
but it was her choice.</i> - This is shock number two.
[buzzing] - It's really painful. - Shock number three.
[buzzing] - It's half over.<i>
- Exactly.</i> <i> It may hurt more, but she's
getting it over with quickly.</i> - Shock number four.
[buzzing] Number five.
[buzzing] Number six.
[buzzing] - Okay, you're done. <i> Meanwhile, our other subject
is only on shock number one.</i> [buzzing]<i>
That's one shock down,</i> <i> five more to go.</i>
[buzzing] <i> While the pain level
may be lower,</i> <i> the subject has plenty of time
for the pain</i> <i> and its anticipation
to occupy his mind.</i> [buzzing] - Hi, Jerome,
would you come with me? - Oh, okay.<i>
- Finally, his hour is up.</i> Tell me about why you chose
the lower voltage choice. - I guess you're--
less pain, you know. - While you were sitting there waiting for ten minutes
to elapse, how did you feel? <i> It's so quiet in there,</i> <i> so basically you got
your thoughts.</i> <i> Your thoughts is like,
"Okay, it's coming."</i> <i> - This anxiety may be the
reason why</i> <i> in the original study,
a full 70% of subjects</i> <i> opted to receive the more
painful shocks right away,</i> <i> rather than suffer through
the mental torture</i> <i> of anticipation.</i> Why did you choose
the higher shock group? - Just knowing that it was over
within a minute, <i> I think ten seconds
is easier to go along with</i> <i> and anticipate
what was coming next.</i> So it's kind of like ripping a band-aid off,
I guess. - You'd rather--
- Hard and fast. - Hard and fast?
- Yeah. - Yeah, yeah. <i> [soft music]</i> <i> ♪ ♪</i> Tickling may be annoying, and pain may be, well,
painful, but we crave touch. Hugging feels amazing. Hugging can actually decrease
your risk of catching the common cold. And hugging
can lower blood pressure. Hugging can also release
oxytocin, the so-called
bonding hormone. I guess what I'm trying
to say is... stay in touch. <i> [electronic music]</i> <i> ♪ ♪</i>
