Hi! John Hess from Filmmaker IQ.com and today we’re going to tackle the one question that

every animal loving filmmaker has pondered…

Do pets watch television?

To answer the pet question we must first the question of ourselves - how does television

or motion picture in general work on us?

Now the major pitfall that muddies our understanding in human or any animal perception is the assumption

that our visual senses operates the same way a video camera does.

After all in a world with miraculous camera technologies, it’s easy to forget that our

inventions weren’t necessarily designed the same way as our senses - they were designed

to fool our senses.

Yes there are many correlations between the physics of cameras and how our eyes operate.

But vision is so much more complicated.

The eye has no frame rate, the eye has no real resolution...

What the eye has are different kinds cells, Photoreceptor cells, Bipolar cells, Ganglion

cells, Retinal Horizontal cells and Amacrine Cells.

The photoreceptor cells are the ones you’re probably familiar with - the Rods and Cones

that are responsible for detecting light.

The signal from these photoreceptor cells is continuous - unlike a camera sensor that

is sampled over time in frames.

Also unlike a camera not every signal from every cone and rod gets sent to the brain,

the information is carried by bipolar and amacrine cells to the Ganglion cells that

form the optic nerve.

A fair bit of processing occurs here as there are Ganglion cells sensitive to light, shape

and color.

The signals are compressed if you will and sent down the optic nerve to the Lateral geniculate

nucleus in Thalamus where it is further processed before finally sending bits and pieces off

to different parts of the visual cortex of the brain which makes sense of what exactly

we’re looking at.

So although our vision also requires a lens and photosensitive cells, unlike a video camera,

our vision is processed in completely different and not yet fully understood way.

Motion pictures took advantage of the peculiarities of our visual system to create illusions - and

to begin to understand that story, we must go back to a huge movement in psychology in

the early 1900s.

The main tenet of Gestalt Psychology is that we perceive the world in a holistic manner

- In other words our eyes may see the trees but our minds see the forest.

We take in the details but our minds construct an understanding of the whole or “Gestalt”

which can be independent and different than the sum of the parts.

This is a departure from the “Structuralist approach” that believes we can understand

the whole by understanding the structural components.

Take a look at this Olympic logo: It appears as a series of five interlocking rings.

But why do we see five rings?

Why not a series of complicated geometric figures - four footballs and several uncompleted

circles and three aches…

It’s because instead seeing the components we see the whole.

Our brains can even fill in missing information.

Take for instance this figure.

We all clearly see a square - it’s plainly obvious despite the fact that there is no

square at all - only circles missing one quadrant.

Our ability to create new information translates to the illusion of movement in motion pictures.

Max Wertheimer one of the founders of Gestalt Psychology was playing around with a stroboscope

children's toy and noticed that light could appear to be to be moving between two different

lamps if you flicked them on and off in rapid succession.

This led Wertheimer to the discovery of the Phi Phenomena and Beta Movement: The illusion

of motion created in the viewer’s mind when seeing a series of still images in rapid succession.

So how fast do we need to change these still images in order to trigger the illusion of

movement?

Well the answer is surprisingly low - only about 10-12 frames per second give or take.

The motion may not be particularly pleasing at 10 frames per second depending on how fast

it’s moving but that is roughly where the illusion begins.

Now a minimum of 10 frames per second might work fine for a paper flip book, but when

we start creating images using bright light either with film projections or on a television

screen, we run into another biological hurdle: The Flicker Fusion Threshold

Let’s imagine an animated sequence on celluloid film.

In order for a projector to advance from one frame to the next we would need to blackout

the projector during the change out or else we would see a blur.

If we played back the animation at say 10 frames a second with a frame of black between

each frame - the result, as you can see here, would be an intolerable amount of ficker.

Even at 24 frames per second, the frame rate settled on in Cinema after the arrival of

sound - this flicker would be unwatchable.

To solve the flicker problem we have crack up our projection rate past our flicker fusion

threshold.

The flicker fusion threshold is the frequency at which our brains fuse a pulsating light

into something we see as solid and always on.

This is related, in a way, to the idea of Persistence of Vision - the image you see

stays in the mind for a fraction of a second even after it’s gone in real life - For

example when you blink you don’t suddenly notice the whole world going dark.

The flicker fusion threshold is based on several parameters that include: the amplitude and

depth of the light modulations, the wavelength of the light, where in our visual field do

we see this light, the ambient lighting, and even our age and level of fatigue.

In a darkened movie theater Thomas Edison, through trial and error found that 46 cycles

per second was the the bare minimum needed to create a flicker free experience.

But instead of running 46 frames per second of expensive film through the projector, the

solution was to show each frame more than once.

Using a multi-bladed shutter on a projector, we can increase, what we might call, the refresh

rate of the projector without increasing the actual frame rate.

So this animation now at the sound era cinema standard of 24 frames per second would be

projected at a rate of 48 times per second with a double bladed shutter just higher than

Edison’s recommended minimum.

But remember how I said that the flicker frequency was based on a number of factors.

As screens got bigger and brighter, the flicker becomes more noticeable so projectors would

employ a triple bladed shutter raising a 24 frame per second film to get the refresh rate

up to 72 hz.

From what I understand, not a lot of pets were exposed to the flickering images in the

movie house.

But there’s no question that they might have seen a television screen at home.

The technology for creating images on the TV screen is a bit different and for the first

50 years or so the cathode ray tube reigned supreme.

Inside a cathode ray tube or CRT, a stream of electrons is guided by magnets onto a phosphor

coated screen.

When the stream hits the screen, the screen glows.

By alternating the magnetic field, this stream of elections is guided along a path that draws

every other line of the television screen.

It completes this half scan at the same frequency as the power line - so here in the United

States, the half scan is drawn in 1/60th of a second.

Once this scan is complete the magnets move the electron stream back to the top of the

screen to draw the second half of the scan in the next sixtieth of a second.

After two scans, a frame is complete resulting in 30 interlaced frames per second.

Because this scan rate is at 60 hertz in the US (and 50 in countries operating in PAL),

it is above our flicker fusion threshold so we see a solid image on screen.

But some animals can see better than we can… whether the television is something fascinating

or just a flicker box depends on their eyesight capability and our emerging television technologies.

Before getting too much further into this this topic I want to address this difference

between Frame Rate and Refresh Rate.

You’ll find that there is a tremendous amount of confusion not only in the pop-science articles

but in some scholarly papers as well.

The refresh rate is how many times per second the television is updating the image.

Modern TVs are capable of refreshing the screen 60 or 120 times per second, some claim up

to 240hz and high end plasma TVs claiming 600hz (although those two might need asterisks

in how they make those claims).

But that doesn’t mean the actual image is changing that fast.

If the frame rate is lower than the refresh rate and in the world of recorded video it

usually is, then, just as with film, the same image is held on screen for multiple cycles.

For instance this 30 frames per second video in a 60 hz screen would hold each frame for

2 cycles.

In situations where the math doesn’t work out as cleanly, such as 24 into a 60hz stream,

we use a pull down scheme like 3:2 where we hold the first frame for 3 cycles and the

next frame for 2 cycles, then 3 then 2 and so on.

Here you can see how we’ve put a 24, a 30 and 60 frame per second video all on the same

60hz stream.

You get some judders on the 24 frame stream but once televisions start getting into 120hz,

those judders go away.

So Refresh Rate is the number of times per second a display updates which may different

than the frame rate which is how many times per second the image actually changes.

These are two separate things so as we talk about refresh rates in the next section we

are NOT talking about frame rate.

Let’s start with the Canis lupus familiaris - man’s best friend the common dog.

Through behavioral studies scientists determined the critical flicker fusion frequency or CFF

of a dog is around 80 hertz.

So those CRT television sets and movie projections?

Forget it, they would just look like an annoying flickering screen.

But there’s still hope for Doggie Programming: the three latest and most popular technologies

in flat panel televisions may have eliminated flicker from equation.

Let’s start with the most basic: the LCD.

An LCD television creates an image using a liquid crystal screen illuminated by a backlight.

For the purpose of our discussion, I’ll skip over how an LCD works although there’s

lots of great videos on the topic.

Let’s focus on the backlight.

Early LCD monitors used cold cathode fluorescent lamps (CCFL) that fired on and off at 60hz.

This would have presented the same flicker issue to dogs as a CRT television but recently

manufacturers have started using CCFLs with much higher flicker rates in the neighborhood

of 200hz.

Higher end televisions utilize bright LEDs to provide the backlight - commonly called

LED TVs even though they use an LCD.

LEDs on their own produce light through direct current so there should be no flicker: perfect

for dogs and other animals with high CFF.

However to control the brightness of the backlight, some manufacturers will use Pulse Width Modulation

which flashes the LED on and off very quickly.

LED brightness can also adjusted using voltage which is harder to do but doesn’t introduce

flicker and some manufactures use both PWM and voltage to adjust screen brightness.

Another potential source of flicker comes from a technique used to fix display induced

motion blur called backlight strobing.

If the pixel is slow to respond in an LCD display, you might see motion blur as the

LCD tries to catch up to fast moving motion.

Strobing the backlight limits this effect but depending on the speed may not be kind

to a watching canine.

OLEDs and Plasma televisions are two technologies that don’t have backlights.

In an OLED television, each pixel behaves like a Light-Emitting-Diode only made out

of organic materials - hence the name.

Each pixel therefore emits its own flicker free light.

In Plasma displays each pixel contains a mixture of neon and xenon gas, that when applied a

voltage turn into plasma and emits again a flicker free light.

So with modern televisions powered with more flicker free light sources, dogs that could

once see the flicker of a CRT screen, can now at least start making out what’s going

on in a movie.

Some studies have shown that dogs will recognize an image of another dog on a computer screen.

Cats have a CFF of 55hz so they’ve always been able to see the screen.

The question more is if they even care and that always seems to be the question when

it comes to cats.

Birds for the most part, evolved a higher Flicker Fusion Frequency to deal with the

rigors of flight.

The household budgie or Parakeet has a 75 hz CFF.

Chickens have 80 hz while the Rock Dove Pigeon has a 100 hz critical flicker fusion.

However they may still be able to see some motion even in 60hz televisions.

A study trained Burmese fowl to peck out of certain colored bowl after watching a 32 minute

training video of other birds feeding out of the same colored bowl.

An analysis of the Flicker Fusion Thresholds across various specials seem to indicate a

corollary between metabolism, size and CFF.

Smaller higher metabolism animals have higher CFF like the Ground Squirrel which is 120

hz whereas larger slow moving animals have lower CFF.

The Leatherback Sea Turtle only has a CFF of 15hz.

Of course this is a corollary relationship using incomplete data and there are

several outliers like the Yellowfin Tuna which has a CFF of 80hz and the Gecko which only

has a CFF of 20hz.

There’s a lot of rabbit holes to uncover in this topic.

It’s really easy to get carried away with the specificity of these numbers when it comes

to vision.

It’s important to remind ourselves that the visual system should not be thought of

as a electronic camera.

These numbers we give are at best just statistical markers.

Our vision can be much better or much worse depending on the situation - no one number

rules supreme.

Critical flicker fusion frequency is just ONE measurement we have so far for understanding

how we and other animals react to light displays.

But Flicker Fusion only tells us that the screen appears solid.

When it comes to non-human psychology all the stuff we covered in regards to Gestalt

Psychology, whether or not the motion appears fluid or if it bothers the viewer, do animals

understand montage and the language of cutting, do they have the same emotional reaction to

music or color - all of that we cannot say with any certainty.

Perhaps watching TV is like going on an acid trip for a dog or perhaps our evolutionary

similarities to other mammals means we have more of a common reaction.

We have a hard enough time understand each other’s experiences and we humans have the

tool of language - to understand our animal companions is even more difficult.

It’s the ultimate mystery - what are they thinking when we share our world with them?

But it is the delightful question every pet owner loves to ponder...

So go out there, make something Fido might like - make something grr grr great.

I’m John Hess, and I’ll see you at Filmmaker IQ.com