Dr Michelle Dickinson: nanotechnologist on scientists discovering a new colour with lasers

Imagine seeing a colour so vivid, so unlike anything in nature, that your brain has no reference for it. That’s exactly what happened to five people who took part in an experiment published in the journal Science Advances this week. 

The newly perceived colour, which is described as a hyper-saturated blue-green shade, has been named olo, and it unlocked a visual experience that was previously impossible with natural light alone. 

To understand the experiment, we first need to understand how we see colour. 

At the back of your eye lies the retina, which contains three types of photoreceptor cone cells - S, M, and L cones -each tuned to different wavelengths of light: 

• S cones respond to short, bluish wavelengths,
• M cones to medium, greenish wavelengths,
• L cones to long, reddish wavelengths. 

Together, they allow your brain to mix and interpret the colours of the world around you. But here’s the catch: in nature, the M and L cones are almost always activated together due to how their sensitivities overlap. This means it's essentially impossible to isolate just the M cones with regular light. As a result, a truly pure green, seen by stimulating only M cones, is something no one had ever seen - until now. 

The researchers used pinpoint lasers and advanced optics to stimulate individual photoreceptors in the human eye. 

Using a laser no more powerful than a standard green laser pointer, the team was able to target cone cells with surgical precision. 

First, they needed to create a cone map, a detailed image showing the exact arrangement of cone types on each participant’s retina. This map allowed the system to fire microscopic pulses of light solely at the M cones, leaving the others in darkness. 

When volunteers looked into the laser system, they described a colour that doesn’t exist in nature. Some said it was like a supercharged peacock green, others just stared in amazement. As soon as the laser was adjusted to stimulate even a few non-M cones, the olo colour vanished and was replaced instantly by the familiar green of the laser. 

The implications of this go far beyond a cool visual trick and open up new possibilities in both science and medicine. By allowing researchers to control cone cells at this level of precision, it may help us: 

• Understand how colour vision truly works on a cellular level,
• Simulate what it's like to lose certain types of vision, helping us study degenerative eye conditions like macular degeneration,
• Explore how to expand human perception, possibly giving people with colour blindness access to colours they've never seen before or even enable humans to experience tetrachromacy. 

Sadly, most of us will never get to see olo ourselves, but its discovery is a powerful reminder of how much there is still to learn about the human body, even something as seemingly simple as colour. 

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Episode Transcript

Speaker 1 (00:06):
You're listening to the Sunday Session podcast with Francesca Rudgin
from News Talks EDB.

Speaker 2 (00:12):
And doctor Michelle Dickinson is with us now with our
science study of the Week. Good morning, Good morning. This
is interesting, this whole idea of us experiencing a new color.

Speaker 3 (00:24):
Yeah, well not us, just five people, probably never few humans.

Speaker 2 (00:29):
Yes, yes, So.

Speaker 3 (00:31):
Scientists have just found out they're calling a new color.
They've called it ololo and can it can't be experienced naturally,
and so that's why only five people in the world
have ever seen it and probably will ever see it.
And if you want to read it, it's published in
the journal Science Advances this week, so you can see
all the experiments that they did. But basically this new color.

(00:55):
Let's go back. Let's forgret how we see color. So
humans can see color because in the back of our retina,
we have three types of photoreceptor cone cells. So in
high school you might have learned about rods and cones.
Cones help us to see color, and we've got three
of them, the S cones, the M cones, and the
L cones, and they're all tuned to different wavelengths of lights.
So yeah, s one see sort of short bluish wavelengths,

(01:17):
your m cones see the medium greenish wavelengths, and your
L cones see their long reddish wavelengths, and combining all
of those together, as hell, we see in color. And
that's all great. And what we've realized is natural light
is so mixed that actually the m cones, the ones
that see green, they're never activated on their own. So

(01:39):
usually the type of light that we see around us
means that the m and the L cones are always
activated together because they've got a bit of a sensitivity overlaped.
And so scientists realize that we have never seen the
world when just our m cones are activated, and so
they went, let's just do that where it gets a
bit frightening. I don't think I'd volunteered for this. So basically,

(02:01):
they scanned the back of the eyeballs of five volunteers
and they did a map of all of the cones
in the back of the eyeballs, and I were able
to identify which type was witch. And so they found
all of the m cones and then they used a laser,
a green laser, and it was so precise and so

(02:21):
powerful that they were able to shine this laser only
on the m cones, so they didn't activate the s
or the l's, so for the first time in these
people's lives, only the m cones were activated. And they
asked them what they saw, and the volunteers like, they
didn't have any words for the color that they can see.
They described it as life changing, the most intense. Some

(02:45):
of them called it a peacock green, like that really
intense bluis green color. But they were like, but it's
not that it's stronger, it's different. They didn't have any
words for it. And then just to prove that it
is because of the m cones, they wobbled the laser
a little bit, which meant that some of the other
types of cones got activated, and immediately that magical color
was lost, and they basically the green if you think

(03:07):
of a green laser like, they saw that standard green
color again. So yeah, they basically shone lasers and people's
eyes so they could see this new olo color, and
the people said it was mind blowing.

Speaker 4 (03:20):
I'm lucky them lucky people, which just feels a bit
mean to do something like this, Michelle and tell us
how amazing it was an ingo, but never mind, none
of your live to experience that.

Speaker 3 (03:32):
It's amazing. What it's done is it's allowed scientists to
understand more about how our color vision actually works at
a cellular level and what the cones actually do. It's
also helped us to understand a little bit about degenerative
I conditions like macular degeneration and why that because some
of that affects the cones, and why that might happen.
But get this, then the scientists are like, hold on.

(03:53):
What we could do is not only help people with
color blindness, but we could allow humans to experience what's
called tetrachromacy, which is where you get to see almost
in like four D color, which is what some insects do,
and it's sort of a bit like sci fi. See,
scientists got a little bit over excited, I think, and
now they're talking about doing the next level of color
so we could see in four D color. So yeah,

(04:14):
some good stuff color blindness, maybe we're understanding more about it,
and some weird stuff tetrochromacy. If that's the next thing
we want to see, it might be coming.

Speaker 2 (04:22):
Thank you so much for talking us through that, Michelle,
much appreciate. We shall talk to you next

Speaker 1 (04:26):
Week for more from the Sunday Session with Francesca Rudkin,
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