- [Narrator] Have you ever knocked on wood for good luck?
This superstition stems from an old Pagan belief
that spirits live in trees,
and if you knocked on the tree,
you were seeking the help from the good spirits,
or making sure the bad spirits couldn't hear you,
and cause you harm.
Seems kind of silly, right?
So, why do people still do it today?
The word superstition comes from
the Latin words super and stare.
- It implies a superior attitude,
and a standing point higher than yours.
It means, I have a better explanation.
- [Narrator] Phillips Stevens is an expert
on what some psychologists call magical thinking.
Like when people were in a bad mood say,
they got up on the wrong side of the bed this morning.
Superstitions are examples of magical thinking.
- When we use the word superstition,
it more often than not, has to do with the control
of good or bad luck, where as magical thinking,
is not necessarily about luck,
but just about, sort of, how something can cause
something else, even when there's no,
sort of, scientific evidence that those things
would be causally connected.
- I've made my family disappear.
- [Paul] It's this sort of a belief
that doesn't have an evidential base,
even though no one can even understand.
They say 13's an unlucky number.
You know, my elevator in my building
doesn't have a 13th floor.
That's a totally crazy thing.
- [Narrator] While seemingly crazy,
Stevens says most superstitions derive
from three universal principles across all cultures.
We all do them, to some extent.
- They represent...
Cognitive features of humanity,
somehow rooted in our evolutionary biology.
- [Narrator] The first is a belief in a higher power.
- [Stevens] A mystical, supernatural power,
that is found in all things.
- [Narrator] This power is thought to be transferred
through things like language, and symbols.
- [Man] Indeed.
- People everywhere believe in a coherent
interconnected universe.
- [Narrator] For example, the cross in Christianity
can be used as a personal amulet,
which holds the power of God.
- Catholics do the sign of the cross on the body, right?
With the right hand.
But crossing the finger can be done with either hand,
and it can be done out of sight.
You're invoking the power of the cross.
- [Narrator] The second cognitive feature
is the principle of similarity.
- Things that resemble other things
have a causal relationship with those other things.
- [Narrator] Breaking a mirror for example,
is thought to bring seven years bad luck.
- The image and the reality are connected.
If you break the image,
you do some damage to the reality.
It's the same sort of belief as the so called voodoo doll.
- [Narrator] The seven years part of it
comes from The Bible, and is not meant to be specific.
- All cultures have ideas of long time and short time,
and in biblical thinking, seven years is a long time.
- [Narrator] The third and final principle
is contact, or contagion.
- Things that have been in direct contact
with other things, retain that contact
after they are separated.
- For example, what do we avoid
walking on cracks on the floor?
- The crack is damaged, and by stepping on the crack,
you may transfer some of that damage into yourself.
- [Narrator] Or, why don't we open umbrellas indoors?
An umbrella is exposed to a storm,
a bad thing, which you could spread by way of the umbrella.
- Things of outside stay outside.
They are not brought inside,
because they might bring inside
some of the unpredictability,
the danger, the potential chaos of the outside.
- [Narrator] This is also why warriors
would leave their helmets outside,
to not bring the battle into their home,
a place of peace.
Early umbrellas were also made with a spring mechanism,
that could have caused bodily harm to someone
if it malfunctioned indoors.
- Some superstitions derive out of practical behaviors.
- [Narrator] People avoid walking under ladders,
because it will supposedly bring bad luck.
One popular theory behind this,
is that a ladder propped against a wall
creates three sides of a triangle.
The number three is holy,
particularly in Christianity with the Holy Trinity.
When you walk under a ladder, you're violating the Trinity,
and therefore causing bad luck.
- The simplest explanation in this case,
is the best one.
It's potentially dangerous.
- [Narrator] Basically, if people are working
on a ladder, there's a chance
that something could fall on your head.
- It just makes more sense to walk around it.
- [Narrator] A number of superstitions
can be traced back to early religious beliefs,
which are intertwined with magical thinking,
like the unlucky number 13.
- This derives from the Christian story of the last supper,
that Seder meal in that upper room on a Thursday night.
- [Narrator] There were 13 people at the table,
with a 13th person being condidered either Judas,
who betrayed Jesus, or Jesus himself.
Jesus of course, died on the cross the next day, a Friday.
Hence, the unlucky nature of Friday the 13th.
When you pass by a cemetery, do you hold your breath?
The origin of this superstition
comes from the ancient belief
that the breath and spirit are the same.
In Hebrew, breath and spirit are the same word, Ruach.
Spirits are thought to hang around cemeteries,
and there's a chance you could breathe in their spirit,
which would not be a good thing.
As you can see, the origins of many
of these common superstitions are a little absurd.
Jane Risen says there are both motivational,
and cognitive reasons why people are superstitious.
- The motivational side is that superstitions
can help us manage the uncertainty,
and the stress and tension that comes from
not knowing what's gonna happen.
- [Narrator] On the cognitive side,
there are two systems of thinking that help explain them.
System one, and system two.
System one refers to things like your intuition,
which helps you make quick decisions
about your surroundings.
- Some set of mental processes are super fast,
and efficient, don't require and cognitive resources,
don't require working memory,
just kinda work (snapping) like this,
and they're basically, you know,
most of life is in that system one space,
and you couldn't function without it.
- [Narrator] But your intuitions can also
encourage superstitious behavior.
You've always been told to avoid cracks in the street,
so you're going to do it just in case,
since it doesn't take much effort.
- In the sort of, slower, deliberate system two,
these are the mental processes that require
more working memory, and more effort,
and that's what you need to sort of,
recognize that these beliefs don't necessarily make sense,
but they still don't stop the intuitions from coming.
Right, so even when you can, sort of, recognize
that this doesn't make sense,
it doesn't stop you from having the feeling
that if I do this, blank will happen.
- [Paul] People are very reluctant to eat a piece
of good chocolate shaped to look like a dog doo.
Now, you could call that a superstition
if you want, it's irrational.
It isn't a dog doo, it's a piece of chocolate,
and they know that.
Their system two knows that, but system one says,
it looks like a dog doo, it is a dog doo.
Generally a good rule,
if it looks like something, it's something.
But in that sense, it becomes misapplied.
- [Narrator] So despite how crazy
these superstitions may seem,
you're not likely to stop knocking on wood any time soon,
if your brain has anything to say about it.
I refused to break a mirror in real life for this video,
you know, just in case.