- When it comes to illusions,
optical illusions get all the attention.
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]
[electronic music]
♪ ♪
Rosanna Pansino. - Hello, Michael.
- Welcome to "Mind Field." - [chuckles]
- Rosanna Pansino is the host of the YouTube cooking show
"Nerdy Nummies."
- Brain cake. Mmm.
- So I thought she would be the perfect candidate
to try out our hot dog illusion.
- 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.
[tranquil music]
♪
- 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.
Husbands can actually sympathize
with their pregnant wives so much
that they experience the same problems,
such as weight gain, insomnia,
nausea, mood swings, et cetera.
Sympathy pain is also known as synesthetic pain.
It's pain sparked by seeing someone else get hurt.
- Ooh!
- Amputees can actually be more susceptible to it
because experiencing trauma can make the brain more sensitive
to other people's pain.
Amputees can also feel pain in the limb
that is no longer there.
That is known as phantom pain.
But perhaps the most surprising way
that the brain and pain interact
can be demonstrated by the nocebo effect.
Have you ever heard of the placebo effect?
It's like when a fake pain pill
actually cures a person's pain
because they have a positive expectation it will work.
Well, today,
we're demonstrating the exact opposite.
If a subject expects
they're going to experience something unpleasant,
like pain, will they feel it
even if it actually exists only in their mind.
We've told our subject that she's participating in a study
to test a non-invasive bone density scanner.
But actually, it's a totally fake machine
that we built from a desk lamp, an air compressor,
and the kind of $10 laser pointer
you might tease your cat with.
It doesn't cause physical pain, or for that matter,
physical sensation of any kind.
It doesn't hurt at all. You guys, this doesn't work.
[laughter]
But will the expectation alone
make our subject think she's feeling real pain?
- 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.
- First, we have to make our subject
expect to experience pain.
And to do that, our actors are going to scare her a little.
Sorry, Jessica, this is for science.
- 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.
- By the look on her face,
it appears we have successfully primed our subject
for what's to come.
- Okay, Jessica, we're ready for you.
- The question is, when put to the test,
will she actually feel pain
when there is really none there.
- This is Jessica. - Hi.
- Hi, Jessica. Come on in.
Won't you have a seat?
- Everything in this room,
the medical equipment, the hospital supplies,
even the demeanor of our fake nurse,
is designed to play on Jessica's mind.
To psychologically induce the anticipation of pain.
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.
Notice how we are suggesting that she will feel pain,
further raising her expectations.
- 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.
- After only about seven seconds,
she's already feeling a physical sensation on her skin,
where there is none.
Keep in mind, we tested our fake bone scanner,
and the light emits zero heat or feeling of any kind.
- 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.
- According to the pain assessment scale,
she experienced significant pain.
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]
- Here's another test of our nocebo.
Will she feel an increase in her level of pain
if she expects to?
- Mm-hmm. [machine humming]
- Keep in mind, level two is fake.
We're not doing anything different than before,
meaning nothing is happening to her.
- So, yeah, it started off higher
than the last time, I think.
It's definitely, like, already stinging.
- Immediately, she reports increased pain on level two.
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.
- The power of suggestion was so strong,
our nocebo caused our subject to think
she felt almost the worst pain imaginable.
Other subject felt different imaginary sensations.
- 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 was surprised at the intense reaction
some subjects had to a feeling that was created
only in their minds.
- 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.
- What about our original subject
who experienced a severe 9 1/2 on the pain scale?
How will she feel when she learns it was all in her head?
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.
- The power of suggestion is so strong
that this subject continued to imagine a physical sensation,
even after learning it wasn't real.
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.
Part of what makes you laugh when you're tickled
is the element of surprise.
Your brain doesn't know exactly what to expect
or when it's going to happen.
On the other hand, it's impossible
to tickle yourself.
If the brain knows where and when and how
you are going to be touched, you won't laugh.
But professors of cognitive neuroscience
at the University College London
have invented the tickle machine.
Subjects sit in the tickle machine
with their feet against a brush
that is connected to a handle.
At first, when the subjects turn the handle,
the brush rotates at the exact same time
resulting in no tickling.
Then the machine is switched into tickle mode...
- [laughing]
of less than a second between when the subject
turns the handle and when the brush moves
against their foot.
- [laughing]
is enough to prevent the brain's cerebellum
from predicting the sensation,
thus allowing the subject to respond to the tickle.
- [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.
So my parents quickly took me to my pediatrician.
- 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,
being that I have had so many injuries during my childhood,
as I get older, I won't feel the pain that comes with it.
Other than that, really,
I just try to live my life normally
as everyone else does.
- 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.
So not being able to feel pain is actually a bad thing.
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.
The CIA and Guantanamo Bay are known
for using psychological torture
involving the anticipation of pain
against prisoners in the war on terror.
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.
We're basing our investigation
on an anticipation of pain experiment,
conducted at the University College London,
which gave subject two options.
Option one: Experience intense pain right away.
Or option two: Anticipate a lower level of pain
in intervals every few minutes.
Researchers found that the psychological effects of dread
can often be worse than the pain itself.
We decided to demonstrate the phenomenon
by setting up a fake research study.
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.
- Now it's time for our subjects
to make an important choice.
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.
the higher, more painful shocks,
but get it over with right away?
Or choice B is one low voltage shock
every ten minutes for one hour.
Or will they choose the lower shocks,
but be forced to anticipate the pain for ten minutes
between shocks for a solid hour?
Either way, you will be here for an hour.
What's worse? A higher level of pain?
Or having to wait and anticipate
the lower level of pain?
- I'll take the long.
- I think I'll do the shorter,
uh, more painful one.
- Okay.
Now that they've made their choices,
it's time to see how our subjects
experience these two options?
The subject who chose to anticipate
the lower level of pain during the course of an hour
is seated in the low shock administration room,
along with our actors,
who are pretending to get shocked.
- Hi.
- This subject's hour-long ordeal is just beginning.
But what about the subject who chose to get it over with
and take the more painful shocks right away?
- We're starting now.
Here's shock number one. [buzzing]
- Ow! - Okay.
- Yes, the shock is painful, but it was her choice.
- This is shock number two. [buzzing]
- It's really painful.
- Shock number three. [buzzing]
- It's half over.
It may hurt more, but she's getting it over with quickly.
- Shock number four. [buzzing]
Number five. [buzzing]
Number six. [buzzing]
- Okay, you're done.
Meanwhile, our other subject is only on shock number one.
[buzzing]
five more to go.
While the pain level may be lower,
the subject has plenty of time for the pain
and its anticipation to occupy his mind.
[buzzing]
- Hi, Jerome, would you come with me?
- Oh, okay.
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?
It's so quiet in there,
so basically you got your thoughts.
Your thoughts is like, "Okay, it's coming."
- This anxiety may be the reason why
in the original study, a full 70% of subjects
opted to receive the more painful shocks right away,
rather than suffer through the mental torture
of anticipation.
Why did you choose the higher shock group?
- Just knowing that it was over within a minute,
I think ten seconds is easier to go along with
and anticipate what was coming next.
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.
[soft music]
♪ ♪
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.
[electronic music]
♪ ♪