>> So it's my great pleasure that we are
able to have Roy Feinson here with us today.
He calls the DC metro area home, he originally
came from South Africa and he earned a degree
in photographic science and
visual communication.
Definitely a background that shaped his broad
interest over the years and really drives
where he's had his invention and impact areas.
Roy had designed graphic and
scientific software applications
that have had significant intersections
with the work we do here at NIST.
His company, Double Take Images has
developed a video analysis system
that assists law enforcement and
enhancement of video tape and film.
And it's currently being used by
the California law enforcement.
Roy also holds a patent from 1988 that's
the foundation of Predictive Text.
The software that interpreted what word you
were trying to spell out on the phone or keypad
and the days, you know, in the days before we
all had smart phones with QWERTY keyboards.
And perhaps what Roy is best known
for is his pioneering the art
form of impressionist mosaics.
That's artwork composed of
hundreds or thousands or images
of stone tiles using the natural
flaws and marbling to create an image.
And so he's used this technique to generate
artwork from mosaics or other images or photos.
He's a very renowned artist.
He's been commissioned for
a number of big events.
To celebrate the 50th anniversary of the
Grammys and as well as to the 50th anniversary
of Disneyland and Disneyland California
Adventure Park and the state of Hawaii.
And I was looking on line on some of his mosaics
that he did for Disneyland and I had just been
to Disneyworld last week for
spring break with my kids.
And I think you missed one kind of vital image
which would be people standing
in lines for hours.
>> Laughter
>> Maybe next time.
So further example of Roy's, you know,
really broad and renaissance-like interests
and talents are, he's authored several books.
Focused on evolution underpinnings
of human behavior.
From the "Animal in You" which explores the
biological reasons for why people tend to act
like different animals to some degree.
To the "Secret Universe of Names"
which looks at how [inaudible]
of how sounds influence human behavior.
And today he'll be speaking with
us on his latest thinking on animal
and human behavior centered on
the mechanism of animal vision.
And so we at NIST will be
able to relate to the source
of Roy's first thoughts on the software glitch.
So many breakthroughs in research originate
from a mistake or a chance finding.
And so, you know, having the creativity
to turn that unexpected outcome
into an ingenious new theory
is really a powerful thing.
And so please join me in
welcoming me Roy Feinson to NIST
and give him a warm round of applause.
>> Applause.
>> Hi Jason, thank you very much
for the introduction and NIST,
thank you very much for having me here today.
I'm going to try and get my talk going here.
Okay. I've called my talk Zebra
Stripes because it addresses one
of the endearing biological mysteries
that really had no satisfactory answer.
Biologists have always felt that the zebra
stripes are a result of camouflage purposes
or perhaps to confuse tsetse flies or to allow
foals to find their mother in a huge herd.
Unfortunately none of these theories are
particularly satisfying and this is one
of those questions that have sort
of been pushed aside by biologists
because there really is no satisfactory answer.
What I hope to do today is answer that question
and in order to do so I have to present
to you a brand new theory of animal
vision and my goal is to change your mind
on everything you think you
understand about how animals see.
And at the end, it's provocative and I'm hoping
that the questions and the challenges that come
from this audience will take it on.
The first thing, excuse me, the first
thing to understand about vision is
that it's not really a function of the eyes.
Vision is really a brain function.
It's the brain's attempt to create
a virtual, a virtual representation
from the two dimensional
images that fall in our retina.
It's quite a challenging task.
So if you imagine when we look at a scene we
have two two dimensional images on our retinas.
The brain then has to create
this model in our brains to sort
of hopefully represent the real world.
It does this through a number of shortcuts
because the process is actually
very technical and difficult.
And a good illustration,
excuse me, a good illustration
of how sometimes these shortcuts don't
work is this well-known Adelson illusion.
If you take a look at the
squares marked A and B,
they're very clearly two
different shades of grey.
But in fact this is a trick
that your brain is playing.
And if I remove everything from the scene with
the exception of those two squares you will see
that they are actually the
identical shades of grey.
Now even if I go back to the original,
intellectually you know they're the same and
yet your visual system keeps insisting
that they're differently colored.
So you have to be careful of
interpreting what you see.
What you see always isn't reality.
Now one fundamental of vision
and a very important aspect
of it is called shape identification.
The ability to look at the outline of an
object and identify it either as friend or foe.
This is such an important component of
animal vision that it's been established
that even baby goslings from the time
that they're born have these shapes
already imprinted in their brain.
So a newborn gosling will come out of its nest.
If an eagle flies over the gosling will duck.
If it is it's mother it will
actually rise up and greet it.
So a very important function of animal vision.
But before the brain can
discern these shapes it has
to pull these shapes out from the background.
And some of you might be familiar with
this process, its called edge detection.
The ability to separate the
edges of an object in a scene.
Now this is actually quite a complex task and if
you look at the formula below this formula has
to be applied to every pixel in every frame
at 30 times a second as it moves through.
With those expensive square root
calculations this can put a lot
of strain on any kind of processer.
In fact, artificial vision researchers tend
to get bogged down by this because there is
so many calculations that
have to be made every second.
Certainly this is a challenge
for a brain as well.
Now human beings have evolved a gargantuan
brain compared to those of animals.
If you compared, say to a mouse, it's
on the order of 1000 times more volume
and we use almost 40 percent of our
grey matter just to process vision.
That's a huge amount of processing power.
And the question arises, for us to see the way
that we do it takes an enormous
amount of grey matter.
How on earth could a mouse or a cat
or even a fly see as well as we do?
Certainly they don't seem to have any problem.
They can hunt, they can fly around at
full speed without bumping into objects.
And yet there must be something
they are giving up.
This is another one of those
biological questions
that really hasn't been satisfactorily answered.
So let's discuss the possibilities of what may
be that they could be giving up in their vision.
The first suspect is, maybe they just
see the world in much lower resolution.
Sort of this blurry low resolution world.
In fact we found that animals actually, in
many cases, have better acuity than we do.
They can resolve two separate
points much finer than we can.
In terms of visual field animals actually
see more than we do at any one moment.
So again, there is more data
that they have to process.
When it comes to depth perception we find that
animals with the possible exception of this one,
can actually see in three dimensions
at least as well or better than us.
And when it comes to sensitivity clearly animals
like cats and dogs can see better in low light.
So we haven't found any overhead savings yet.
Perhaps it's got to do with
vision, color vision.
Now human beings are trichromatic
which essentially means
that we can see the entire
color spectrum quite well.
Cats and dogs do have a truncated
version of that.
They tend to see more in the greens.
Snakes on the other hand are
very much towards the red end
of the spectrum including the infrared.
And birds such as Birds of Paradise and
parrots are what's called heterochromatic,
they actually have a much better
color spectrum than we do.
They can pick out hues that
we are unable to do so.
And significantly and we're going
to talk about this a little later.
Birds of prey, like hawks and owls, raptors.
They tend to see mostly in the greens.
And the reason -- if you -- you can
actually look at a bird and decide
which what they're color vision
is by looking at their plumage.
Birds with wide spectrum ability tend
to be brightly colored whereas raptors
and owls tend to be brown and grey.
And finally there's an aspect of
vision called flicker fusion rate.
Flicker fusion rate is defined as the frequency
of still images that we need to see in order
to create the continuously moving stream.
So kind of like looking at a movie.
Human beings, our flicker fusion
rate is 30 frames a second.
Which means that if we watch
a movie at around 25
to 30 frames a second we see
a continually moving object.
Predators, on the other hand like dogs and
cats, actually see at 70 frames a second.
And house flies with their tiny, tiny brains,
actually take in information
300 frames a second.
Which they need to do because they live in a
world of fast moving tails and fly swatters.
So they can't afford to miss a
single frame of activity as they go.
But this is counter intuitive because it seems
on the surface that if information is coming
in at 300 frames a second the amount
of data could be overwhelming.
I mean, we see it at 30, they see at 300.
So this is the mystery of what animals
give up -- give up is actually deepened.
So now I want to tell you about an
incident that happened a number of years ago
when I was working on some
forensic video software.
I had filmed this ruler for reasons I won't
go into, being pulled by a piece of string
and I ran it through my processor
expecting a certain result.
What I got back was a very strange
result that looks something like this.
And this, obviously I realized
I had screwed up somewhere and
but I wasn't quite sure what was happening.
On a hunch I did the same thing and this
time I put a black mark running parallel
to the direction of movement and
ran that through the processor.
And I got something identical
to what I'd seen earlier.
So pursuing this further I wrapped some
tape at one inch intervals around the ruler,
perpendicular to the direction
of motion and I got that.
So now I thought, this is very interesting.
That objects that were perpendicular
to the course of motion showed up,
objects that were parallel to it didn't.
What was actually going on is something
that I called delta processing.
If you -- what the software was doing was,
it was looking at each successive frame
of the video and where a pixel had
changed in value from one frame to another
that was rendered onto the new video.
If nothing had changed nothing was rendered.
So in this example of this dog wagging
its tail, you'll see that the tail --
only the tail is visible as well as that
patch of green grass behind the tail
which also changes from frame to frame.
So this is delta processing, and
it's going to form the foundation
of this new theory of animal vision.
I came up with a hypothesis that
perhaps what animals are actually giving
up in their vision is everything.
That animals actually see nothing except the
things that change in their visual field.
Like I said, it's provocative, because
I'm essentially accusing animals
of being blind most of the time.
So how would that work in the real world?
How could animals function, hunt and
escape and navigate under those conditions?
Here's a frame from a video
that I shot back in California.
I'd climbed onto the roof where
the seagulls tend to nest.
I wanted to see the world from their prospective
and this is a single frame
from some video that I shot.
Now this is actually a very complex scene.
If you look at it there is four groups of
people, there's lens flare, there's shadows,
there's trees, there's trashcans.
There's a lot going on.
And if you've got a brain the size of
a seagull it can be quite overwhelming
to sort of keep track of everything.
But this is what I believe
the seagull actually sees.
You'll notice that everything has
dropped away and more importantly,
that issue that we discussed
earlier of edge detection,
that complex mathematical formula that's
required to pull things from the background,
these edges have now been perfectly rendered
without the use of any mathematical formula.
This is just a simple filtering technique
that requires almost no computer
overhead and therefore no brain overhead.
And more importantly the objects that
are most important to the seagull,
such as the person closest to the gull
and walking the fastest is rendered
more heavily than objects further back.
If you look at the people in the top right you
notice that they haven't even rendered at all.
So from the seagulls prospective
they're not a threat therefore the brain
of the seagull doesn't have to
even contemplate their existence.
But I noticed a problem.
This was the result that
I was getting initially.
I was handholding the camera
and those little tiny movements
that I was having were causing pixel
changes on every pixel in the picture.
This is an intolerable situation for a brain.
Even we would have problem trying to
decipher who is what and what's going on.
And I was wondering if possibly
nature had a solution for this.
And it turns out that it does.
This is actually a very deeply
embedded component
of all animal behavior and
that's vision stabilization.
So here's a man moving a chicken in
all different axis and you notice
that the chicken manages to maintain
it's vision fixated on a certain spot.
We notice this in the classic example of
a cheetah running at 60 miles an hour.
It's just beautifully stabilized
and fixated on its prey.
Birds do it as well and for
birds this is very important
because when an eagle is floating a couple
thousand feet in the air, lofted by winds
and it's using its telescopic foveal vision,
it needs to stabilize that even more.
Some researchers even attached some sensors
to a flies head and as the fly zipped
around the room, sort of landing on the
ceiling and doing little twirls and arcs,
they found that it could instantly
move its rostrocaudal axis
around its head keeping it's vision
stable on any particular point.
So flies do it, birds do it, we all do it.
In fact it's the reason we can read in a car.
Even if the car is bouncing up and down we
somehow stabilize the vision on the tiny words
in the newspaper and we can actually read.
Somebody pointed this out to me and
it kind of puzzled me for a while.
[Laughter] If this is true then why does
the pigeon bob its head as it walks along?
I mean it seems to fly in the face of it.
It turns out, a couple of decades
ago some scientists figured out that
in slow motion the bird stabilizes its
head until the rest of its body catches up.
Jerks it forward and keeps it stable.
So wherever you look in nature
you'll be surprised at two things.
One, how well animals stabilize
their vision and how well
and how much time they spend
in a frozen situation.
And we'll get to that in a second.
Finally that flicker fusion problem that I
discussed earlier, that the flies see the world
at 300 frames a second starts to make sense.
In the light of the [inaudible] vision.
So in an example of this frog
leaping quite quickly forward, a fly,
with 300 frames a second flicker fusion rate is
actually going to see less data than an animal
with a slower flicker fusion rate.
And the reason is that the differences
between two successive frames will
be less the faster those frames move.
So there's less data.
In this instance the fly could
easily shape detect the frog.
It has very little other
information to go by, mind you.
It doesn't know what species the frog is.
But it doesn't care.
All it knows is that it's a
frog, it needs to get away.
A dog, on the other hand, with a slower
fusion rate would see more detail.
In this case maybe look at the
markings and the camouflage
and determine maybe this is an edible frog.
And that significant.
When I realized that the flicker fusion
rate was actually providing less data,
everything started to fall into place.
So I began to look at other animal
behaviors looking for evidence for my theory.
And one of the most striking ones I came
across is something called serpentine motion.
It's a very distinctive movement.
Snakes move kind of in the way that a string
would when being pulled through a hosepipe.
So imagine a curved hosepipe, the
string moves through that hosepipe
and in a sense the snake's body is passing
over the path laid down by its head.
So it walks in its own footsteps.
Snakes are unique in that 85 percent of them
are non-poisonous, they have no arms or legs.
They are completely defenseless.
The only defense they have is
their ability to remain hidden
through their particular kind of motion.
So let's look at this video of a black
snake sort of moving across the grass.
It's not so easy to see.
And preparing to strike.
Through the delta vision a potential predator
would not see anything about the snake except
for the portion of the head that
changes as it moves across the grass.
If however, we get a striped
version of the snake,
as we saw earlier we actually see the
entire snake as it moves across the grass.
So why would a snake want to be seen?
Well, clearly a poisonous snake
wants to advertise it's position
so that it's not accidentally
picked off by a bird.
I then found out that there's really
three basic color schemes to snake.
There's the monochromatic snake on the left,
the longitudinally striped snake in the middle
and the banded snake on the right.
Almost all non-venomous snakes are either
monochromatic or longitudinally striped.
And as we saw, they're both
invisible under delta vision.
The only ones that shows up
tend to be the venomous snakes.
And of course there are some
non-poisonous snakes
that mimic venomous markings
but that's another story.
So this is just a summary.
Non-poisonous snakes do not show up.
This is also why I believe there's
a differential between the juvenile
and the adult coloration of certain species.
In this tree viper for example, when the
snake is young and hasn't really figured
out the world, it wants to remain invisible to
predators whereas the adult then starts to take
on the distinctive markings
you see on the right.
Some snakes have even figured
out the best of both worlds.
When the snake is crawling along the
grass it would be invisible to everything
and the only time it wants to be
seen is when it raises to strike
and threaten a potential predator.
I came across this.
And this to me was a fascinating
little sojourn that I took.
This is a very common marking for snakes.
This red and black coloration.
But it's always associated
with non-poisonous snakes.
And I was wondering why a red banded
snake like this would be colored this way
because as it moves across
the grass it's very clear,
as everything we've seen, that
it would be highly visible.
Then it hit me that from its primary
predator's point of view, which are raptors.
Raptor's color vision is centered
around the green end of the spectrum.
It's exactly like looking at the
world through a green filter.
In this case the green filter would absorb all
colors, especially the red and turn them black.
So you'll notice that the red
stripes have turned black and along
with the preexisting black stripes
the whole snake is now monochromatic.
So from the raptor's point of view this snake
is fundamentally invisible throughout its length
of motion.
I thought, wow, that's very clever.
So the snake has figured out a -- the snake
hasn't, the evolution has figured out a way
to hide the snake from its predator.
But why go through all that trouble.
Why put the stripes there in the first place?
Why not simply make the snake brown?
And then it hit me that this snake has
other reasons to have these markings.
From another snake's point of view, a potential
mate for example, who see the world as if
through a red filter, the red stripes now
turn white and are perfectly contrasted
against the black stripes that already exist.
So from a potential date
the snake is highly visible.
So this is an example of coloration
that's both triggered by sexual selection
as well as predatorily selection.
I think it's the only example, at
least that I've come across where some
of these markings have two separate benefits.
You'd also expect that if animals can only see
things that move, you'd expect to see this kind
of behavior in other aspects of animal behavior.
Have a look at this common house cat.
Hasn't been trained in any way,
this is an instinctive behavior.
And it's playfully stalking
the photographer as it goes.
And watch how little movement in the cat until
the cat gets very close to the photographer.
So the photographer is going
to hide off-screen briefly.
[Laughter] And you see this
kind of behavior in the wild
where predators will synchronize their
movements with that of their prey
to essentially disguise their approach.
This is the reason that freezing
behavior is so universal.
The classic example of a
deer frozen in headlights,
to us it doesn't really make
much sense to our vision.
We can walk up to a deer at night with a
flashlight and the deer freezes and we're going,
well, we can see you, why don't you run away?
But the fact is, this freezing
behavior is universal.
Human beings do it.
We talk about being frozen
in fright and certainly
if we're alone at night we will also freeze.
Sometimes involuntarily.
It's carried to extreme examples.
The classic case of a possum playing dead is a
form of freezing that we call tonic immobility
and this tonic immobility is pretty universal.
It happens with goats, it can happen to
rabbits, even pigeons under extreme stress.
And when in absolute fear, human beings as well.
[Laughter] So the question comes, if
animals can only see things that move how
on earth can they navigate in a world
of non-moving inanimate objects.
Why don't we see more of this
kind of behavior from animals?
The answer is that when you move you create
changes in the environment, prospective changes.
So if we look at this video from a dog's point
of view moving through a field of chess pieces
and we show it through the delta vision look
at how beautifully these chess
pieces are edge detected.
And you'll notice that the object closest
to the animal are rendered much more
sharply than those further back.
This is important because the animals foveal
vision, the part of the vision that's going
to analyze what's up, needs to be able to focus
in on the objects that are most important,
which are the objects right in front of it.
If you are a horse running through the jungle
and there's obstacles right in front of you,
they are far more important than
the ones maybe 10 yards away.
And this is how I believe it all fits together.
Its perspective changes faster when you're
close than it does when you're further away.
Okay, now that we've gone through this
whole long explanation we're going
to get back to the zebra.
How does this all explain the zebra's stripes?
In order to do that let's just
look at the nature of the zebra.
Zebra are extremely dangerous animals.
Their hooves can shatter a lion's jaw,
they're the only ungulate in the world
that uses its teeth as a weapon, they outweigh
the lion, they're faster than the lion.
Very aggressive, very powerful animals.
They're not to be taken lightly.
From the lion's point of view, when the lion
decides what to eat, when it has a choice,
it uses a formula that I've sort
of summarized at the top there.
It looks at its choices and it says, what are
my chances of successfully catching the animal?
Multiply by the amount of caloric
reward that I'll get and I divide
that by the risk of injury to myself.
Lions can actually do math, by the way.
All animals do a lot of higher
math, but that's another story.
In this case the carcass on the left has a high
degree of nutrition with zero risk of injury
to the lion and obviously a
100 percent chance of success.
So which is why lions are
primarily carrion eaters.
The only time they hunt is
in the absence of carrion
and then they use this calculation
to choose which prey to go for.
So confronting a herd of zebra and using
that formula, the lion has a problem.
These are very dangerous animals and
it needs to lower it's risk of injury.
The way to do that is to select
an injured, infirm young or old
or diseased animal from the herd.
Lions are very good at picking out
slight changes or limps in gates
and they'll spend a lot of time
hidden in the bushes just watching
and looking for that weakest animal.
Now the lion has a problem however.
That once it's made it choice, and in this case
the second one from the end, the chase begins.
The lion is now going to
run at 30 miles an hour,
hooves are going to be flying,
dust is in the air.
Very low contrast situation, a lot of confusion.
How is it going to be able to keep its
lock on that particular individual?
And thanks to the zebra's stripes, and
this is an actual frame from a chase,
you'll notice that with all this
low contrast difficult environment,
the stripes of the zebra have
somehow, well, not somehow,
they have very clearly delineated
each individual zebra.
The lion cannot help but keep
a lock on its chosen target.
In fact if you look at the way the stripes
of the zebra are designed,
take a look at the torso.
The vertical stripes on the torso.
These are moving perpendicularly to its motion.
As we saw, that shows up well in animal vision.
If you look at its legs and forelocks
those stripes are horizontal.
Those legs are moving up and down.
Also perpendicular to the motion.
The rump which is the combination of
both are nicely conformed at 45 degrees.
So the zebra is actually working
very hard, the zebra's stripes,
to allow the animal to lock
in on its chosen prey.
This is different however,
when choosing a wildebeest.
In this example the lion's choice is not
going to be the weakest of the animals.
Because the wildebeest do not present
the kind of danger that the zebra do.
In this case the lion is actually going
to want to pick the plumpest, juiciest,
healthiest animal there is to
upgrade its caloric intake.
From the wildebeest point of view, however,
this is not a good idea because no group wants
to sacrifice its breeding males and females.
They would rather offer up one
of the diseased individuals.
So the coloration of the wildebeest is
such that the lion cannot keep a lock.
This is a disruptive mechanism.
Monochromatic things, as we saw earlier
with the rule and everything else,
things that are monochromatic do
not show up under delta vision.
So the lion would be presented
with a very confusing scene.
And in no way could keep a
lock on its chosen adult prey.
This is the reason, by the way, that
most prey animals are monochromatic.
And most prey animals do not present
much of a challenge to a lion anyway.
Somebody pointed out, well, what about this?
This is a very common marking in antelope.
For example this spring buck
on the top picture there,
has almost a set of three different colorations.
It didn't take long to figure out what
was going on and the first clue is
that these stripes are run parallel
to the direction of their motion.
Which means that they're
essentially invisible to delta vision.
However, these are pronging animals.
And pronging is a behavior used
by prey animals to show the lion
that they are superior in agility and endurance.
They can spend enough energy going vertical
that the lion shouldn't even
waste its time chasing it.
And what happens now with
these horizontal stripes moving
in a vertical axis the animal
shows up extremely well.
They want the lion to see
it which is also the reason
that their rumps are distinctly colored as well.
So that's either a black or a white rump
in case the lion is coming from behind.
Talking about behinds.
One of the challenges and one of the
mysteries of biology is why zebra
and horses wag their tails when they're
angry whereas dogs do it when they're happy.
And so of course if found
some video of two zebra.
Here we have a stallion on the right
wagging its tail, flashing its tail.
And the mare on the left
standing very still on the left.
If we run that through animal
vision this is what we get.
The tail as it moves across the rump seems
to be painting a nice clear image of the size
and strength of this animal's hind quarters.
This is the killing end of a zebra by the way.
If you're a competitive stallion
and you want to take
on a zebra the reason they flash their
tails is to give you a very clear indication
of what they're going to be up against.
The mare, on the other hand, stands
dead still, doesn't want to be involved
and is actually invisible in that scene.
Dogs, on the other hand, the
killing end is on the front.
So they use their tails as
sort of friendly gesture.
And on these three images of true
wild dogs, we have the dingo,
the wolf and the African wild dog, you'll notice
their tails are bushier than they seem to need
to be and they're all tipped with
a very distinctive end on the end.
So its obviously used as a
visual signal to bring attention
to their hind quarters which is not threatening.
This is a universal behavior that
again has puzzled biologists.
Why do insects, birds, people,
all cock their heads?
And puppies.
[Laughter] Oh, so cute.
I believe the reason is pretty clear if we
look at it through the lens of delta vision.
Have a look at those mathematical
symbols on the left.
Now if you're an animal and you're
looking at a photograph for example.
Everything I've said tells you they cannot
see that photograph unless they're moving.
But one way to see that photograph
is to simply move one's head
which creates delta changes between frames.
The other way to do it is to sort of
nod your head which you can do as well.
The problem is both the shaking and the
nodding don't give you all the detail you're
looking for.
Those are two delta rendered
versions and you can see
that the symbols have not
been rendered properly at all.
They look completely different and
not all the information is there.
The only way to get it is to move your
head in a 45 degree rotation at once.
And then everything clicks into shape.
So I believe that head cocking which is
associated with sort of quizzical behavior
or even fear is a result of this.
If you go to a museum and
you watch people in front
of abstract paintings you will see a much
higher frequency of this than you would
if they were looking at something
that's pretty obvious.
And that's sort of the vestigial
reflex that we have.
Just one word of warning.
Do not -- I learned this the hard way.
Just keep your parental controls
on, you'll be fine.
I'm just going to run through
a couple of animal behaviors
that will help you maybe
observe with your own pets.
Your cats and your dogs.
This happens to my dog all the time.
I throw the ball, the dog perfectly
tracks the ball in the air,
watches it land, sees it
bounce and retrieves it.
If for some reason it misses that point
where it hits the ground and the ball comes
to a standstill, the dog is
actually looking all around.
And it's right there.
And the dog is sniffing so
it tunes out its vision
and starts using its scent to try and find it.
I don't notice if you've noticed with
your dog but try it and see if it works.
Feline [inaudible] are a very common behavior
with cats and I recommend if you have a cat,
do this yourself, when the cat is sort of
just sitting around, walk up to it and freeze.
Your freezing behavior is not something
you're cat is used to your doing
and you will actually be
surprised how well you can freeze.
Human beings have this ability
to freeze extremely well.
The cat is going to sense that
something is up and what's going
to happen is, it will freeze as well.
And in a protracted kind of
tense standoff will ensue.
And what's happening is that you have
disappeared from the cat's visual scene
so the cat actually -- it knows you're there
because it smells you and it saw you earlier.
But it cannot see you.
Which puts it at a disadvantage and what
its hoping for and waiting for is for you
to make the first move so it can paint a
delta image of your position in its vision.
And that standoff can go for a long time.
The cat that moves first is
naturally at a disadvantage.
This is why you see lizard and small
rodent locomotion that works like this.
For this lizard to get from point A to point
B it actually does so in fits and starts.
So it will be stock still and one
thing that this being still allows it,
remember it has almost 360 degree vision,
by keeping absolutely still it can very
quickly detect motion in its environment.
If it detects no motion it will zip forward
maybe five or six feet and freeze again.
So this does two things.
It allows him to check for
predators and also lowers the risk
that a predator will see
that movement on its way.
Watch it with squirrels.
I don't know if you have squirrels where you
live but you'll see that, I see it every day.
If you ever want to put your -- get your
dog some exercise and want to put her
on the treadmill it will balk if
you put it on a standard treadmill.
Their visual system cannot pick up the
changes that occur on a black base.
Paint some stripes on it and the
dog will take to it very quickly.
If you ever want to catch flies, how instinct
for most people is to sort of move as fast
as we can to hit the fly, it's completely
the opposite because the fly easily picks
up that motion at 300 frames a second.
What you can do, you can actually fly underneath
the animal's visual radar and if you move it
at about an inch a second the fly
cannot pick up those delta changes.
So the fly will just sit there
until you're about an inch away,
you can grab it and I guess eat it if you want.
[Laughter] I'm starting to
wonder if we shouldn't try
and explain conventionally
understood behaviors in a new light.
And one of them that comes up is blinking.
There is something about blinking
that's not quite self-evident.
We know that it's a process of protecting
our eyes and lubricating our eyes
but there's something more to it.
Some research recently has shown that people
tend to synchronize their blinking rates.
We do so in movies, people will tend to
blink altogether at the end of a scene.
Or perhaps at the end of a speaker's sentence.
So something is going on there.
Also animals will blink more in the presence
of predators than they would otherwise.
Now I believe that one of the after-effects
of the blink is essentially
a complete visual refresh.
If you're an animal and I'm looking at
this crowd, all I can see are those people
that are moving their hands and legs, but
I can't see anything about the auditorium.
If, however, I blink and open my eyes,
I refresh my visual field completely.
So I briefly get a complete
picture of what's going on.
Human beings blink so much in fact that we
spend about five to ten percent of our day
with our eyes closed because of blinking.
So the question is, well, why don't we have
a clear nictitating membrane like this bird?
That way we could keep our
eyes open all the time.
In fact, birds not only have nictitating
membranes but they also have eyelids.
So they both blink and nictitate
at the same time.
And the only reason that I can
think of is to do this refresh.
Just to kind of give you an idea what the
refresh does, if you look at these two iguanas
from the point of view of a predator,
a blink would create a full
refresh that you see on the left.
It's a complex visual scene.
So its now a cortical, its up
to your cortex to try and figure
out the shapes and actually what's going on.
Whereas if those animals had moved you
would see a much easier clearer vision.
So blinking is not a perfect
solution but its better than nothing.
And finally, I was wondering if maybe there's
some more vestigial artifacts in our own vision
that harkens back to our
evolutionary animal past.
And I came across this experiment
done in the 1950's
where a Dr. Pritchard had attached a tiny
projector to the surface of a woman's eye.
And it was projecting an image
directly onto her retina.
And what this allowed him to do was
stabilize that image onto her retina so even
as her eye moved the little cycads in
her eyes sort of wobble back and forth,
the image was fixated on particular cells.
And she reported seeing this image of
a cat for about two or three seconds
and then saying, you've turned it off.
When in fact he hadn't.
So the fact that the retina turned off
the visual impulses after about two
or three seconds, at least in some way indicates
that maybe our own visual system is
fundamentally grounded in that animal behavior.
Brain damaged patients, whether through
stroke or car accident, neurologists report
that when somebody's visual cortex is severely
damaged, so much so that they're blind,
they almost always retain
the ability to see motion.
So if found this quite interesting
because here we're dealing almost
with an animal visual system.
You cannot see anything except things in motion.
So I'm hoping that some more research
will be done with those patients to see
if we can piece together how the world
would look if you were a cat or a dog.
And finally, you know, some of
the big biological questions,
the explosion in cranial size
over the last five million years.
This is the granddaddy of all biological issues.
What triggered this?
We're not sure.
I don't believe we will find
the answer unless we consider
that vision played a big roll in this.
Because vision takes up so much of
our own brain power and gives --
and modern human vision gives
us so many advantages
that it could have easily sparked
an arms race amongst early hominids
to trigger the increase in
brain size and visual cortex.
So human vision gives us the ability
to make tools, to read books.
And essentially see into the future.
We can look at a scene like this and imagine
around the corner there's a verdant
valley with a lake that will help us.
So the advantage of human vision
cannot be underestimated and I believe
that so many aspects of biology have
to be reconsidered in that light.
And now the best part of this is
that I get to take your questions
and to hear your challenges to the theory.
And I thank you very much
for listening and thank you.
[Applause]
