Oh, excuse me!
Have you ever yawned because somebody else yawned?
You aren't especially tired,
yet suddenly your mouth opens wide
and a big yawn
comes out.
This phenomenon is known as contagious yawning.
And while scientists still don't fully understand
why it happens,
there are many hypotheses currently being researched.
Let's take a look at a few of the most prevalent ones,
beginning with two physiological hypotheses
before moving to a psychological one.
Our first physiological hypothesis
states that contagious yawning is triggered by a specific stimulus,
an initial yawn.
This is called fixed action pattern.
Think of fixed action pattern like a reflex.
Your yawn makes me yawn.
Similar to a domino effect, one person's yawn triggers a yawn
in a person nearby that has observed the act.
Once this reflex is triggered, it must run its course.
Have you ever tried to stop a yawn once it has begun?
Basically impossible!
Another physiological hypothesis
is known as non-conscious mimicry,
or the chameleon effect.
This occurs when you imitate someone's behavior
without knowing it,
a subtle and unintentional copycat maneuver.
People tend to mimic each other's postures.
If you are seated across from someone that has their legs crossed,
you might cross your own legs.
This hypothesis suggests
that we yawn when we see someone else yawn
because we are unconsciously copying his or her behavior.
Scientists believe that this chameleon effect is possible
because of a special set of neurons known as mirror neurons.
Mirror neurons are a type of brain cell
that responds equally when we perform an action
as when we see someone else perform the same action.
These neurons are important for learning and self-awareness.
For example, watching someone do something physical,
like knitting or putting on lipstick,
can help you do those same actions more accurately.
Neuroimaging studies using fMRI, functional magnetic resonance imaging,
show us that when we seem someone yawn or even hear their yawn,
a specific area of the brain housing these mirror neurons
tends to light up,
which, in turn, causes us to respond with the same action:
a yawn!
Our psychological hypothesis also involves the work of these mirror neurons.
We will call it the empathy yawn.
Empathy is the ability to understand what someone else is feeling
and partake in their emotion,
a crucial ability for social animals like us.
Recently, neuroscientists have found that a subset of mirror neurons
allows us to empathize with others' feelings
at a deeper level.
(Yawn)
Scientists discovered this empathetic response to yawning
while testing the first hypothesis we mentioned,
fixed action pattern.
This study was set up to show that dogs would enact a yawn reflex
at the mere sound of a human yawn.
While their study showed this to be true, they found something else interesting.
Dogs yawned more frequently at familiar yawns,
such as from their owners,
than at unfamiliar yawns from strangers.
Following this research, other studies on humans and primates
have also shown that contagious yawning
occurs more frequently among friends than strangers.
In fact, contagious yawning starts occurring
when we are about four or five years old,
at the point when children
develop the ability to identify others' emotions properly.
Still, while newer scientific studies aim to prove that contagious yawning
is based on this capacity for empathy,
more research is needed to shed light on what exactly is going on.
It's possible that the answer lies in another hypothesis altogether.
The next time you get caught in a yawn,
take a second to think about what just happened.
Were you thinking about a yawn?
Did someone near you yawn?
Was that person a stranger or someone close?
And are you yawning right now?
(Yawn)
(Lip smacking)