What it means if you can see faces in objects - Susan G. Wardle
Imagine opening a bag of chips only
to find Santa Claus looking back at you.
Or turning the corner to see
a smile as wide as a building.
Humans see faces in all kinds
of mundane objects,
but these faces aren’t real—
they’re illusions due to a phenomenon
known as face pareidolia.
So why exactly does this happen, and how
far can this distortion of reality go?
Humans are social animals,
and reading faces is an important part
of our ability to understand each other.
Even a glimpse of someone's face can help
you determine if you've met them before,
what mood they’re in,
and if they’re paying attention to you.
We even use facial features
to make snap-judgments
about a person’s potential trustworthiness
or aggression.
To capture all this vital information,
humans have evolved to be very sensitive
to face-like structures.
Whenever we see something,
our brain immediately starts working
to identify the new visual stimuli
based on our expectations
and prior knowledge.
And since faces are so important,
humans have evolved several regions
of the brain
that enable us to identify them
faster than other visual stimuli.
Whereas recognizing most objects takes
our brain around a quarter of a second,
we can detect a face
in just a tenth of a second.
It makes sense that we'd prioritize
identifying faces over everything else.
But brain imaging studies
have revealed that regions
may actually be too sensitive,
leading them to find faces
where they don’t exist.
In one study, participants reported
seeing illusory faces
in over 35% of pure-noise images
shown to them,
despite the fact that nothing was there.
It might seem concerning that our brains
can be so wrong so often,
but these illusory faces
might actually be a byproduct
of something evolutionarily advantageous.
Since processing all the visual input
we encounter quickly and correctly
is an enormous computational
effort for the brain,
this kind of hypersensitivity might
act as a useful shortcut.
After all, seeing illusory faces
is usually harmless,
while missing a real face can
lead to serious issues.
But for hypersensitivity to be
more helpful than harmful,
our brains also need to be quick
at determining when a face is real
and when it isn’t.
So how fast can our brains tell
when they’ve been duped?
To answer this question,
researchers used a form of brain imaging
known as magnetoencephalography.
By measuring the magnetic fields caused
by electric currents in the brain,
this technique allows us to track
changes in brain activity
at the scale of milliseconds.
With this tool, researchers revealed
that the brain generally recognizes
a face as illusory
within a quarter of a second—
around the same time that we can identify
most non-face visual stimuli.
However, even after our brain
knows the face is fake,
we can still see it in the object.
And by messing with these brain areas,
we can further impact our ability to
differentiate between fact from fiction.
In one study, researchers stimulated
a participant’s fusiform face area
while they were looking
at a non-face object.
As a result, the participant reported
momentarily seeing facial features
despite the object remaining unchanged.
And while looking at a real face,
stimulation of this same area
created perceived distortions
of the eyes and nose.
These studies suggest that certain
features are crucial to face detection.
Just three dots can be enough
to represent eyes and a mouth.
People will even assign gender, age,
and emotion to illusory faces.
It’s unclear whether a person’s culture
or individual history
impacts these perceptions,
but we do know that pareidolia isn’t
unique to the human experience.
Rhesus macaque monkeys show eye movements
similar to our own
when observing pareidolia-inducing objects
and real faces,
suggesting that this phenomenon is baked
deep into our social primate brains.
So, next time you see an unexpected
face in a coffee, car, or cabinet,
remember that it’s just your brain
working overtime
not to miss the faces that really matter.
