[On-screen] The National Eye Institute: Celebrating 50 years of advances in vision research
[On-screen[ Color vision
[Dr. Bevil Conway] Ah, the famous dress.
Yes, the dress that broke the internet.
[Dr. Jay Neitz] The phone rang and I picked it up and it was a reporter.
The person said, “You have to see this!”
[Dr. Bevil Conway] One of the things about this dress that’s so compelling is that
there are these individual differences in how people experience it.
[Dr. Jay Neitz] It’s kind of an optical illusion, and we’re not exactly sure what
it is about different people’s visual system, but it has to do with how we’re interpreting
the situation.
[Dr. Bevil Conway] The dress image became this really powerful example of what I take
to be an important component of why we have color vision to begin with
[On-screen] Color vision: An evolutionary tool
[Dr. Jeremy Nathans] The evolution of color vision in humans—and really, it’s the
evolution of color vision in higher primates and our primate relatives, our close relatives—evolved
because we were looking for things in the environment that were differentially colored
ripe fruits tend to be brightly colored and unripe fruit tends to be green, and that distinction,
to be able to see a red or orange or yellow object among the green leaves is one that
we’re very good at and almost certainly drove the evolution of primate color vision.
[Dr. Sheldon Miller] The sense of color has been observed and recorded and appreciated
over several thousand years at least since the time of Aristotle.
The notions of color vision and visual sensors in the eye were discussed in the 17th and 18th centuries by Newton and by
Thomas Young and Helmholtz in their wave theory of light and by Clerk Maxwell in his discussions
of the trichromacy of color.
Maxwell was able to provide a set of so-called color matching functions that provide you
with a unique representation for every color.
You can always find a set of amounts of red, green and blue that will match any color that
you have here.
That tells you that the visual system is trichromatic.
[On-screen] How we perceive color
[Dr. Sheldon Miller] The retina contains three receptors each with a different photo pigment
or a visual pigment whose peak sensitivity is in the short wavelength by the spectrum,
the middle part of the spectrum and a long wave part of the spectrum.
Those three separate types of photoreceptors, the combination of the activation of those three separate
photoreceptors is what allows trichromacy and the ability to perceive color in a three-dimensional
world.
[Dr. Jeremy Nathans] There are some people who are missing either all three or two of
the three, and those individuals live in a black, white, and gray world.
[Dr. Jay Neitz] And if you went and took a black and white camera and went through an
impressionist art gallery, it wouldn’t have a big impact—or a black and white camera
looking at the sunset or the rainbow or the autumn leaves.
None of these things that we find so compelling. It’s all about the color and the
effect it has on us.
[On-screen] Using color vision to understand the brain
[Dr. Bevil Conway] Color is fascinating because it informs a lot of the way in which we interact
with the world in ways that are often unconscious. It’s just an important aspect of our engagement
with the world, almost like a primary thing.
[Dr. Sheldon Miller] In recent years, there has been increasing focus on color perception
and the neural processing or the electrical processing that is required to carry out to
interpret perceptions in the brain.
Neuroscientists are now beginning to unravel the connection between these electrical circuits
in the brain that mediate color and they are discovering how these electrical circuits
also contribute to a higher order cognitive function such as emotion, attention, decision-making,
memory and language.
[Dr. Bevil Conway] Using non-invasive imaging, we decided to look in the brain using non-human primates, monkeys as
a model and humans, using non-invasive imaging to try and look at the different parts of
monkeys and humans that respond to color.
And to our great surprise we discovered that enormous parts of both monkey brains and human
brains are activated by color.
In the parts of the brain that we thought were reserved for high level object vision:
face recognition and object memory and problem-solving and so on.
So we’ve now been in this process of trying to understand what those parts of brain are
doing.
So this is color now not because I’m interested in color; it’s color as a tool to try and
address this very basic question about how the brain works, how it’s organized.
[Dr. Jeremy Nathans] Color vision is a sense that we have all lived with, we’ve all grown
up with it.
We think we understand it because it seems so intuitively obvious, but in fact the calculations
that the brain and retina perform are very complex, very sophisticated, and they give
us a color world that is in many ways different from the objective world around us, in the
sense that color has been manipulated—in some way, color is a mental construct of the
world.
[Dr. Sheldon Miller] You are aware of your emotional self.
You are aware of your memory.
You are aware of your language skills.
It turns out that at some deep level, the way the brain works, the ability to process
color and the ability to experience memory, to experience emotion and to experience language
are intimately involved.
[Dr. Sheldon Miller] Color can also be used to probe the behaviors associated with emotion, with language.
Those are functions that are intimately define us as human beings.
[On-screen] NEI is continuing to explore color vision to gain a deeper understanding of how the brain works.
[On-screen] To learn more, vist nei.nih.gov