What you’re looking at right now is an optical illusion.
While I’m talking, focus on the center, and think about how easy it is to fool your
eyes and your brain.
Hello easily tricked simpletons, Jules here for Dnews.
Before we begin, I’d just like you to know that your eyes are lying to you.
Right now.
Sight is simply a perception of reality which we assume to be true because practically,
it works.
But what you think you’re seeing is actually reflected light waves, flipped upside down,
reversed, then converted into electrical impulses, reinterpreted and finally projected as visual
consciousness.
This whole process takes a little less than a tenth-of-a-second.
Now, that tenth of a second delay is way too long.
If you’re an early ancestor hunting fish and your fishing spear is off by a tenth of
a second, you’ll probably miss.
So to bridge the gap, and to make all of its processing duties easier, your brain makes
predictions about where things in your field of vision will be, and sometimes it just makes
things up all on its own.
That’s where optical illusions come in.
Optical illusions are basically hacking your eye-to-brain connection by predicting where
your brain is likely to screw up and send you false information.
There are effectively three types of optical illusions: literal, physiological, and cognitive.
A literal illusion is the simplest, and can be demonstrated in this drawing by American
illustrator Charles Allan Gilbert called All is Vanity.
At first glance, the image appears to be of a skull, but as your eyes adjust to the details,
it is in fact a woman sitting at her vanity mirror.
There are no skulls in the image whatsoever, but nearly all viewers see a skull.
Why?
Well, as I said earlier, your brain does everything it can to bridge the tenth-of-a-second delay,
and one of these methods is by filling in details based on pattern recognition.
In this instance, the image in front of you has enough “skull-like” patterns that
your brain initially reads it as a skull, which saves it the energy of processing every
shape and color and angle.
Literal illusions work by approximating a different object or setting closely enough
to fool your brain for a moment before all the details settle in.
The next type is a little trickier, and is called a physiological illusion.
Take a look at this grid and try to count the grey dots at the intersections.
What’s that?
They keep disappearing?
Gotcha!
But this illusion, which was discovered by Ludimar Hermann in 1870 and is thus called
the “Hermann grid”, is not based on your brain’s mistakes, but the limitations of
your retina.
Specifically, it is believed to be based on something called “lateral inhibition”.
See, light-receiving neurons in your eye -- photoreceptors -- are arranged in rows.
When one of them is stimulated by light, the surrounding neurons are inhibited and respond
less strongly.
Your eye does this to filter out a lot of light noise, keeping the most dominant neurons
brightly lit and creating contrast with less dominant light sources.
In the Hermann grid, at the intersections, your receptors are flooded with white light
from four sides.
This creates a lot of lateral inhibition, and the receptors in those areas respond less
strongly, making the intersection appear darker.
But, if you look directly at any one intersection, the grey disappears.
This is because the center of your vision has a significantly higher concentration of
photoreceptors and creates a clearer picture than anywhere else in your eye.
And finally, there are cognitive illusions.
These are, in my opinion, the coolest, because they take place far away from either your
eye or the purely visual processing center of your brain.
These illusions happen in your understanding of the image itself and your existing knowledge
of the world.
Look at this famous staircase, known as the Penrose stairs, which directly influenced
famous optical illusion maker, MC Escher.
The trick with both Penrose and Escher is that the image is physically consistent with
how a staircase works, but practically impossible.
You’d be going down or up forever.
According to the father and son team which created the staircase, "each part of the structure
is acceptable as representing a flight of steps but the connexions are such that the
picture, as a whole, is inconsistent."
The image doesn’t make any sense while having no actual flaws.
Your brain doesn’t know what to do with the conflicting information, and so it accepts
a totally paradoxical image.
Gottem!
Ultimately, your brain and eyes take a lot of shortcuts for efficiency, but at the expense
of accuracy.
And by the way, although these are the most prevalent theories we have right now, almost
all of these explanations for optical illusions have been challenged.
The reality is, we’re not great at figuring out why our eyes and brains are so screwed
up.
So the next time you see something crazy, it’s more likely that it’s your own faulty
processing system, and not a total collapse of the universe and its functions.
What are your favorite optical illusions?