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OPTICAL ILLUSIONS SHOW HOW WE SEE. A TED TALK BY BEAU LOTTO.

02 01: SEEING ILLUSIONS


SEEING COLOR IS ONE OF THE SIMPLEST THINGS THE BRAIN DOES.


And yet, even at this most fundamental level, context is everything. What I want to talk about is not that context is everything, but why is context everything. Because it’s answering that question that tells us not only why we see what we do, but who we are as individuals, and who we are as a society. B E AU LOT TO


02: Seeing Color pg. 11-18

01: Seeing Illusions pg. 05-10


03: How The Brain Sees pg. 19-24

04: What It All Means pg. 25-30 02 CONTENTS


TO UNDERSTAND HOW WE SEE CORRECTLY, WE NEED TO UNDERSTAND WHY IT SEEMS THAT WE SOMETIMES SEE INCORRECTLY. ILLUSIONS, THEREFORE, ARE CRITICAL WINDOWS INTO THE MIND.


ARE THESE SQUARES IDENTICAL?

01 OPTICAL ILLUSIONS SHOW HOW WE SEE


OR THIS ONE’S DARKER?


In the previous example, both grey squares are the same. What does it tells us? Context is everything when it comes to perception, or in fact everything. The deeper question is not that context matters, but why context matters. Why the

Context is everything.

brain can’t help to see two things that physically the same look different when put in different surroundings. By understanding it, it will also answer that question that tells us not only why we see what we do, but who we are as individuals, and who we are as a society.

09 OPTICAL ILLUSIONS SHOW HOW WE SEE


The beautiful thing about illusions is that they make us realize not only that things are never what they seem, but also that our experiences of the world shape our understanding of it. The whole concept of an illusion is predi-

Why do we see illusion?

cated on a misconception. When you see

an illusion, you are entertaining two reali-

ties simultaneously. The brain causes the illusion by in that moment trying to make

sense of what the eyes are seeing. You’re

in the position of actually experiencing yourself having an experience.

Illusions are useful as a research tool

because they tell us how the brain works, that the brain evolved not to see the retinal

image (which is made up of meaningless, or ambiguous, patterns of light) – i.e. not the world ‘as it is’ – but to see the world in a way that proved useful in the past. It constructs what it knows by searching for useful patterns in sensory information and then associating those patterns with a past record of their behavioral relevance, and then using that information to guide behavior. Which means that the brain is innately a creative and curious machine that evolved to continually redefine normality, a ‘normality’ that is necessarily contextual and historical.

10 01: SEEING ILLUSIONS


COLOR IS NOT LIGHT. LIGHT IS A LINEAR DIMENSION OF WAVELENGTHS, FROM SMALL WAVELENGTHS TO BIG WAVELENGTHS. THE PERCEPTION OF COLOR IS NOT A LINEAR DIMENSION; IT’S A THREE DIMENSIONAL PERCEPTUAL SPACE.


To see color, you have to have light. When light shines on an object some colors bounce off the object and others are absorbed by it. Our eyes only see the colors that are reflected. The sun’s rays contain all the colors of the rainbow mixed together. This mixture is known as white light. When white light strikes a white crayon or marker barrel, it appears white to us because it absorbs no color and reflects all color equally. A black crayon or marker cap absorbs all colors equally and reflects none, so it looks black to us. While artists consider black a color, scientists do not because black is the absence of all color. All light rays contain color. Light is made of electromagnetic waves. These waves spread out from any light source, such as the sun. Light waves travel at tremendous speed (186,000 miles or 300,000 kilometers per second). Different colors have different wavelengths, which is the distance between corresponding parts of two of the waves. The longest wavelength of light that

What is color?

humans can see is red. The shortest is violet. Ultraviolet has an even shorter wavelength, but humans cannot see it. Some birds and bees can see ultraviolet light. Infrared has a longer wavelength than red light, and humans can not see this light but can feel the heat infrared generates.

13 OPTICAL ILLUSIONS SHOW HOW WE SEE


Considered to be part of the brain itself, the retina is covered by millions of lightsensitive cells, some shaped like rods and some like cones. These receptors process the light into nerve impulses and pass them

How do we see color?

along to the cortex of the brain via the optic nerve.

Have you ever wondered why your peripheral vision is less sharp and colorful than

your front-on vision? It’s because of the rods and cones. Rods are most highly con-

centrated around the edge of the retina. There are over 120 million of them in each

eye. Rods transmit mostly black and white

There are three types of cone-shaped cells,

information to the brain. As rods are more

each sensitive to the long, medium or short

sensitive to dim light than cones, you lose

wavelengths of light. These cells, working

most color vision in dusky light and your pe-

in combination with connecting nerve cells,

ripheral vision is less colorful. It is the rods

give the brain enough information to inter-

that help your eyes adjust when you enter a

pret and name colors.

darkened room.

The human eye can perceive more varia-

Cones are concentrated in the middle of

tions in warmer colors than cooler ones.

the retina, with fewer on the periphery.

This is because almost 2/3 of the cones

Six million cones in each eye transmit the

process the longer light wavelengths (reds,

higher levels of light intensity that create

oranges and yellows).

the sensation of color and visual sharpness.

About 8% of men and 1% of women have some form of color impairment. Most people with color deficiencies aren’t aware that the colors they perceive as identical appear different to other people. Most still perceive color, but certain colors are transmitted to the brain differently. The most common impairment is red and green dichromatism which causes red and green to appear indistinguishable. Other impairments affect other color pairs. People with total color blindness are very rare.

14 02: SEEING COLOR


15

OPTICAL ILLUSIONS SHOW HOW WE SEE

REFLECT. AND YOU WILL SEE IT.

THE QUALITY OF LIGHT THAT THEY

SEE THE SURFACES ACCORDING TO

YOU’RE DEAD. FLIP THE PAGE TO

AND IF YOU HAVEN’T SEEN IT YET,

CAN YOU SEE THE PREDATOR THAT’S ABOUT TO JUMP OUT AT YOU?


So, color enables us to see the similarities and differences between surfaces, according to the full spectrum of light that they reflect. But what you’ve just done is, in many respects, mathematically impossible. Why? Because, as Berkeley tells us, we have no direct access to our physical

What is color for?

world, other than through our senses. And the light that falls onto our eyes is determined by multiple things in the world– not only the color of objects, but also the color of their illumination, and the color of the space between us and those objects. You vary any one of those parameters, and you’ll change the color of the light that falls onto your eye.

16 02: SEEING COLOR


The same image could have an infinite number of possible real world sources. The light that falls on to your eye, sensory information, is meaningless, it could mean literally anything. And what’s true for sensory information is true for information generally. There is no inherent meaning in information. 01 OPTICAL ILLUSIONS SHOW HOW WE SEE


IT’S WHAT WE DO WITH THAT INFORMATION THAT MATTERS.


THE BRAIN EVOLVED NOT TO SEE THE RETINAL IMAGE, BUT TO SEE THE WORLD IN A WAY THAT PROVED USEFUL IN THE PAST. THE BRAIN IS INNATELY A CREATIVE AND CURIOUS MACHINE THAT EVOLVED TO CONTINUALLY REDEFINE NORMALITY, A ‘NORMALITY’ THAT IS NECESSARILY CONTEXTUAL AND HISTORICAL.


21

OPTICAL ILLUSIONS SHOW HOW WE SEE

ATTRIBUTES, LIKE LANGUAGE. HERE ARE SOME LETTER STRINGS. CAN YOU READ THEM?

W AT A E OU REA I G?

SIGNIFICANCE, BY INTERACTING WITH THE WORLD. WE’RE VERY AWARE OF THIS IN THE FORM OF MORE COGNITIVE

RELATIONSHIPS IN INFORMATION AND ASSOCIATING THOSE RELATIONSHIPS WITH A BEHAVIORAL MEANING, A

WE SEE BY LEARNING TO SEE. SO, THE BRAIN EVOLVED THE MECHANISMS FOR FINDING PATTERNS, FINDING


Half the letters are missing. Right? There is no a priori reason why an “H” has to go between that “W” and “A.” But you put one there. Why? Because

How did we do that?

in the statistics of your past experience it would have been useful to do so. So

you do so again. And yet you don’t

put a letter after that first “T.” Why? Because it wouldn’t have been useful in the past. So you don’t do it again.

22 03: HOW THE BR AIN SEES


23

OPTICAL ILLUSIONS SHOW HOW WE SEE

BETWEEN DESERT. ARE THEY STILL THE SAME NOW?

DON'T LOOK ANYWHERE ELSE. AND QUICK AFTER THAT LOOK AT THE DOT

BETWEEN THE GREEN AND THE RED. STARE AT THAT DOT FOR 30 SECONDS.

IS SIMPLY THE FLIPPING OF THE OTHER. OKAY? NOW LOOK AT THAT DOT

FIRST, LOOK AT THOSE TWO DESERT SCENES ARE PHYSICALLY THE SAME. ONE


Your brain is learning. And it's learning that the right side of its visual field is under red illumination; the left side of its visual field is under green illumination. That's what it's learning.

24 03: HOW THE BR AIN SEES


SO, ILLUSIONS ARE OFTEN USED, ESPECIALLY IN ART, IN OTHER WORDS OF A MORE CONTEMPORARY ARTIST, “TO DEMONSTRATE THE FRAGILITY OF OUR SENSES.”


Seeing yourself see.

see, what "I" hear and what "I" know is the world as it really is. But, by "seeing

yourself see," in other words by actively

exploring how your thoughts, feelings, beliefs and even the colors you see reflect

your physical, social and cultural ecology,

only then is it possible to understand the

The importance of these observations

source of coherence and conflict within

transcends neuroscience. They show us in

and between individuals. Put another way,

an explicit (and I hope engaging) way that

only by accepting my own humanity can

our senses are not "fragile" -- as many

I accept the humanity of others. "Seeing

would have you believe. They show us in-

myself see" creates the opportunity for

stead that we are not outside observers of

this acceptance. Illusions, then, were not

nature defined in isolation. We are instead

the point of my talk, but simply a tool for

indivisible from nature, defined by the trial

encouraging this process.

and error process of interaction, a process in which we can choose to become active agents (but too often choose not to). Understanding this point is I believe critical to personal and social wellbeing, since the typical barrier to a deeper insight into oneself and others is the overriding, but necessarily false impression that what "I"

27 OPTICAL ILLUSIONS SHOW HOW WE SEE


Celebrating uncertainty.

Resolving uncertainty is essential to our survival. Hence our fear of ambiguous

situations is palpable–e.g., the inability to resolve sensory conflict between the eyes and ears can result in nausea (like sea sickness). And yet it is only by embracing the unknown within education, science, art and most importantly within our own private lives will we find new routes to more enlightened ways of seeing and being. Thus, courage not confidence is at the heart of this process of actively redefining normality, which is the route to compassion and creativity.

28 04: WHAT IT ALL MEANS


We are not defined by our central properties, by the bits that make us up. We’re defined by our environment and our interaction with that environment– by our ecology. And that ecology is necessarily relative, historical and empirical. Because what I’ve been trying to do is really celebrate uncertainty. 01 OPTICAL ILLUSIONS SHOW HOW WE SEE


ONLY THROUGH UNCERTAINTY IS THERE P OTENTIAL POTENTIAL FOR UNDERSTANDING.


FOR FURTHER INFORMATION AND OTHER INSPIRING TALKS GO TO: WWW.TED.COM/TALKS

02 01: SEEING ILLUSIONS


Optical Illusions Show How We See