Name: Why can't you tickle yourself?
Uploaded: 2018-01-06T11:45:04.000Z
Duration: 2 min 41 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

You can tickle your friend, and your friend
can tickle you.

Reflexive pronouns

It's something most people realize when
they're kids.

But for years, scientists have been trying
to figure out exactly why you can't tickle

yourself—and if there's any way to trick
your brain so you can.

When someone else tickles you, it activates
a part of your brain called the hypothalamus,

Some scientists think you laugh when you're
tickled because you're signaling submission

to someone who has you in a vulnerable position.

That might also explain why some people really
hate being tickled, or react by thrashing.

So it makes sense that you can't tickle
yourself, because you can't surprise your

When you start moving your fingers toward
your palm, stomach, armpit, or wherever, your

It knows where your fingers will land and
that they won't hurt you.

But when someone else is tickling you, you
can't predict precisely when and where their

The unpredictability makes you more sensitive
to the touch, and you react by laughing.

It also seems like a sense of agency is a
key ingredient.

The feeling that you are the one in control
of your body's movements means your own

People who have schizophrenia, a neurological
disorder that causes hallucinations, among

other symptoms, seem to lack this awareness
about their own movements.

That insight led researchers to try and come
up with scenarios where people without schizophrenia

In one small experiment, researchers tried
waking people up during REM sleep, when they

They figured that since dreaming is similar
to the hallucinations people with schizophrenia

experience, the subjects might be able to
tickle themselves if they tried right after

Overall, waking people up from REM sleep didn't
give them the ability to tickle themselves.

In another experiment, researchers tried to
make people feel like they were in somebody

They used a modified version of the rubber
hand illusion — a psychological trick where

you can get your brain to feel like a fake
hand is your own if someone else touches it

at the same time as your real hand, which
is hidden from view.

For this experiment, the researchers did a
total body switch.

They had subjects look through video goggles
that showed a feed from a camera on the experimenter's

head, and the experimenter sat across from
them.

Using the rubber hand illusion, they were
able to make the subject feel like they were

inside the experimenter's body instead of
their own.

Then, while they were having this trippy out-of-body
experience, the subjects tried to tickle themselves.

But even then they rated the sensation as
being less tickly than when someone else tickled

Their brains still knew they were in the driver's
seat, doing the tickling.

So if you really want to be tickled, you're
gonna have to find someone else to do it for you.

And if you want to learn more about the human
brain, check out our new channel, SciShow

Psych, hosted by Brit and Hank, at youtube.com/scishowpsych.