(lighthearted orchestral music)
- Hey and welcome to BrainSTUFF.
I'm Josh Clark and this is the BrainSTUFF
where I explain to you
how color blindness works.
Have you ever been looking
at a rainbow and thought
"Man, what is it like to be color blind?"
That's a really weird thing to
think but here's your answer.
First, though, we should say,
It's actually not called color blindness.
The preferred term is color deficiency.
So let's get a little more PC, shall we?
Now before we understand
how color deficiency works,
we have to understand how
regular color vision works.
In humans, it's called
trichromatic vision.
because we rely on three
different types of cones,
which are specialized cells in the eyes,
that contain photopigments,
and a photopigment is a protein
that's sensitive to a
certain wavelength of light,
AKA, a color, right?
So, these three types
of cones are attuned to
short wavelengths, which picks up blues,
medium wavelengths, which picks up greens,
and long wavelengths,
which is in the red band
of the visible light spectrum, right?
So when everything's operating correctly,
our eyes are exposed to light
and the different cones send
information to the brain
to let it know what kind of quality
and amount of the type of light
that it's sensitive to,
it's receiving right then.
The brain takes all this
information, puts it together,
and all of a sudden,
these three different color informations
equal a million different shades of colors
that we're capable of seeing.
But what happens when it goes wrong
and you have color deficiency?
Not color blindness.
What you have is what's
called anomalous trichromacy,
which somebody said is the
most beautiful combination
of words in the English language.
I think it was them.
In most cases, color
deficiency is the result
of cones just not operating quite right.
Most of the time, it's
either the red cone,
or the green cone.
The problem is that either the red cone
or the green cone will
mimic the other one.
Rather than enhancing
the cone that it mimics,
it actually cancels out
or mutes the information
from the other cone.
So the sum total effect of all of this
is that the good information
coming from say, the green cone
is being cancelled out or muted
by the mimicking information
coming from the red cone
and since the brain uses
these different shades
to make more colors,
a lot of different stuff
seems kinda dull or gray.
That's color deficiency.
Well, in particular, that's
anomalous trichromacy,
the most common type of color deficiency.
The reason for all of this is genetic,
genetic mutations, actually.
Both of the genes that
lead to the expression
of cones in our eyes are
found on the X chromosome,
which is contributed by
the female, AKA, your mom.
Now if your mom has a
mutation on one of her genes,
you have a 50% chance of some
sort of color deficiency.
If she has a deficiency on both genes,
you have 100% chance of
having a color deficiency,
which is what's called a certainty.
And what's even stranger,
is that a lot of people
who are red-green color deficient
don't know that they are
until they're tested for it.
Luckily, there are ways of curing this.
There are contacts and
glasses that can correct
a little bit of the color deficiency
so you don't have to walk
around feeling so glum
and that everything's just kind of gray.
So now you know about how
color-blindness works.
Thank you for stickin in there with me.
This is a pretty neat one if you ask me.
Now go forth and check
out rainbows everywhere
and while you're at it,
go to our awesome website
howstuffworks.com.
