
What Do Cats See? - hellrich
http://www.mydeals.com/blog/what-do-cats-see/post
======
jobigoud
I think there is one fundamental flaw with simulating color seen by non humans
or dichromat humans. I've seen this in all computer based simulators. They
simply change the weight of some colors relatively to others.

But a dichromat with say, missing L cones will not simply mix green and red,
he will experience "green" totally differently than a trichromat. What a
trichromat call green is the result of the stimulation of both M and L cones.
We cannot see the pure spectral green. We cannot subtract the L cones
contributions to what we experience, and its is quite important. The dichromat
won't have any L cones contribution, the physiological stimuli won't be the
same. He sees the actual spectral green. A color we have never seen and that
we cannot imagine.

Now there is an experiment to do : put a full page of bright red and stare at
it for minutes. It will start to become orange-ish. This is your L cones
getting tired. Now swiftly switch to a bright green full page (prepare it so
you can switch with a key press). You will experience a purer green that you
ever experienced, because this green will have less red component to it as
your L cones are tired (the effect will last mere seconds and quickly fade
into normal green). If you were able to completely remove your L cones, you
would see what the dichromat sees.

~~~
carlesfe
Oh, wow, thas was an incredible experience, thanks!

In trying to explain it some way... the green was SO GREEN that it actually
looked like it was flashing blue.

By the way, is there any other similar experiment I could try?

~~~
arketyp
You might be interested in what is called opponent process theory of color
vision.

~~~
rxzv
I know I can google it, but is there a particular link you recommend to read
up on it?

~~~
arketyp
As it happens I was just researching it myself (it was briefly mentioned in a
lecture on scientific visualization). I found this (have not read yet), what
seems like a thorough and serious treatment of the subject.

[http://www.handprint.com/HP/WCL/color2.html#heringtheory](http://www.handprint.com/HP/WCL/color2.html#heringtheory)

------
dTal
The trouble with "simulations" like these is they ignore cognitive post-
processing - much like visualizations of what it's like to look through a
compound eye portraying it as like looking at a wall of TV sets.

The human images and the cat images are not comparable because the human
images represent a subjective impression, rather than a prediction from visual
capabilities like the cat images. For example, the human images are crisp
right out to near the edges. This is simply inaccurate - you can only read
text within a FOV of about 6 degrees.

~~~
roryokane
I think these simulations _are_ after post-processing. That us exactly why the
human vision picture is sharp past 6 degrees from center - the picture
portrays what we see _after_ our brains stitch together a visual field.

~~~
dTal
The human image is after post-processing. But we do not (cannot?) know what
post-processing cats apply! Their impression of their own visual field could
be just as sharp as ours (and probably is).

------
ecopoesis
Scientists at Berkeley have actually recorded what cats see by scanning a
vision pathway in their brain:
[http://www.berkeley.edu/news/media/releases/99legacy/10-15-1...](http://www.berkeley.edu/news/media/releases/99legacy/10-15-1999.html)

Here's a link to the video: [http://www.youtube.com/watch?v=piyY-
UtyDZw](http://www.youtube.com/watch?v=piyY-UtyDZw)

~~~
mikeweiss
What the hell did they do to that cat! :-(

~~~
angersock
It's a cat scan.

~~~
StavrosK
Badum tish.

~~~
dmix
This is HN, we handle our anti-reddit-style-comments policy like the Stasi.

------
SeanDav
This seems to answer a question I asked myself just yesterday:

A neighbour's cat and my cat had a argument, no actual fighting - just lots of
staring, yowling and that strange growling sound cats make. Nothing too
questionable there, but then my cat did something rather strange - she started
moving away by walking extremely slowly and I mean _extremely_ slowly. I
wondered what on earth she was up to but after reading this article I think it
must have something to do with the fact that cats cannot seem to detect very
slow motion. It appears that cats can move and position themselves in such a
way that it may be undetectable (or nearly so) to another cat.

Of course there may be a completely different explanation, but I like this
one.

~~~
mratzloff
I suspect not. To do so would imply that cats are self-aware, which no one has
been able to demonstrate.

~~~
mratzloff
The idea was that moving slowly implies that they recognized the other cat has
the same limitations as itself.

I am beginning to find Hacker News very tedious when people down-vote posts
that they disagree with which were made in good faith.

~~~
SeanDav
Have you ever seen a pride of lions hunting? The teamwork and understanding
involved there is way beyond that required to recognize that another animal
might not notice if one moves slowly.

One very simple step is they recognize the concept of upwind and downwind, not
to mention the concept of beaters, ambushers and the ability to dynamically
change their strategy when circumstances change.

------
Theodores
This article was substandard for HN. No real mention or explanation was made
of the reflective layer behind the retina, this is the special feature that
gives cats what amounts to night vision, however it is at a cost of
resolution. But hey, VGA night vision is better than a 4K pitch black image.

I have noticed that the cats I know are selectively short sighted. A rival cat
from a neighbouring area or a fox can be spotted at considerable distance,
however, a 'loved human' has to be relatively close to be acknowledged. This
could have been rendered in the images, having it so that 'humans see humans'
and 'cats see cats' in otherwise identical scenes.

Cat view - as in a few inches from the ground would not have been that hard to
do - how difficult is it to take a photo these days rather than just download
something random from the internets?

Furthermore, a cat's eyesight is augmented by an array of whiskers. These can
be moved forward and back and are there to work out what something in close
quarters is doing or shaped like. The cat has this area covered by the
whiskers and has no need to be able to focus there even though we expect them
to when we wave something in front of their noses.

~~~
JetSetWilly
I understand that cats have face blindness. To a human, another human looks
very distinctive and unique as we have been crafted by evolution to notice the
tiniest difference between faces. To a cat, we all look pretty much the same,
it takes them a bit more effort to work out who is who.

------
ChuckMcM
Cats and other animals can see different spectrum, which is useful to their
hunting. Noting that raptors can see infrared so actually 'see' the thermals
they are flying in makes a whole lot of sense from an evolutionary standpoint.

Apropos of nothing, I find this a fascinating way of enhancing the link
authority of a coupon site. Given algorithm changes at Google which punish
sites for little original content, adding a blog like this to your coupon site
ups content that allows you to organically rank higher.

------
danwills
Wouldn't the bokeh (~defocus kernel) shape be changed by the fact that cats
have a differently shaped pupil?

Interesting nonetheless.

------
ogig
I think this misses one of the keys aspects of cat vision, movement
perception. You'd need video for that. I imagine they see something like a
glowing trail around moving stuff. Depeding on light conditions my cat might
ignore food/toy until it moves.

~~~
mhb
The photos miss that, but it is mentioned in the text:

 _The increase in rods also enhances their “refresh rate”, so that they can
pick up movements much faster (very helpful when dealing with small animals
that change direction very quickly during a chase)_

Also: _Interestingly, this also means that humans have the ability to see very
slowly moving objects at speeds 10 times slower than cats (that is to say that
we can see very slow things move that would not appear to be moving to a cat)_

Which made me wonder why sneaking up on a cat chameleon-style doesn't work
better.

~~~
Diederich
You're not moving slowly enough, and cats can hear really well.

~~~
josefresco
And they can probably smell you unless you're down wind.

------
notacoward
If someone would do the same for eagles instead of cats, that would be
awesome.

------
rachelbythebay
Try this instead:

[http://www.wired.com/wiredscience/2013/10/cats-eye-
view/](http://www.wired.com/wiredscience/2013/10/cats-eye-view/)

------
jstalin
I'm routinely impressed that my cat uses a litter box with no problem that is
almost completely dark at night. Not sure how she can see what she's doing,
but it's cool!

~~~
Sharlin
I don't think she needs to see anything (although she probably does, at least
dimly). Even humans should have no problem navigating around a familiar
environment without relying on vision -- especially those humans accustomed to
it, such as blind people. And cats get plenty of help from their other senses
that are considerably keener than their human equivalents.

------
jotm
Don't forget about the scientists who apparently took direct video output from
a cat's brain - it looks like they have a facial pattern recognition similar
to that of ours - what I mean is they look for the eyes/nose/mouth/etc and
most likely see cat-like faces on other animals and humans (like we do when we
think a dog is smiling). Interesting...

------
hnha
that's a blog just to get seo for a "deals" website. to flag or not to flag?

~~~
eli
Prefer the Mail?
[http://www.dailymail.co.uk/sciencetech/article-2462559/Nicko...](http://www.dailymail.co.uk/sciencetech/article-2462559/Nickolay-
Lamm-pictures-Fascinating-photographs-world-eyes-cat--bit-blur.html)

~~~
josefresco
Both the DailyMail and PopSci websites reference this "deals" website as the
source. So while the site doesn't look like official news, from what I can
tell it seems to be the proper source.

~~~
jewbacca
This SEO-looking site does credit Nikolai Lamm, who's also posted the content
on his personal site, with no further attribution for the photos:

[http://nickolaylamm.com/art-for-clients/what-do-cats-
see/](http://nickolaylamm.com/art-for-clients/what-do-cats-see/)

I was surprised to find that the "Art for Clients" tag on his site contains a
lot of content that's gone heavily viral recently (especially "The Average
Man" photos, which were on HN a few days ago):

[http://nickolaylamm.com/category/art-for-
clients/](http://nickolaylamm.com/category/art-for-clients/)

And all these professional news agencies, presumably with legal teams to back
it up, attribute Nickolay Lamm as the source for all of those I checked.

From his "About Me":

> I blog for MyDeals.com, MyVoucherCodes.co.uk and StorageFront.com. Each blog
> post I make takes around 4 weeks to create.

[http://nickolaylamm.com/about-me-2/](http://nickolaylamm.com/about-me-2/)

I smelled something fishy from the "mydeals.com" source from OP, and initially
thought that the Daily Mail's attribution to that site was just sloppy and
awful... but it all checks out. Huh.

------
gbin
if I understand correctly they are short sighted so a good picture to add
would be a macrophotography with a background to see where is their best
vision in terms of depth of field no ?

------
hjc89
[http://twentytwowords.com/2013/10/18/japan-has-two-
islands-t...](http://twentytwowords.com/2013/10/18/japan-has-two-islands-that-
are-overrun-by-domestic-cats-12-pictures/)

------
abhinai
I am not sure if I agree with the blurriness of cat-seen images. Human eyes
are known to be pretty bad in terms of hardware. It is our brain that applies
the wonderful image reconstruction that gives us the perception of crystal
clear images. By scanning the neural pathways that transmit image data to a
cat's brain, researchers have only establish the kind of signals that a cat's
eye sends to its brain, not what a cat actually sees. It is entirely possible
(and very likely) that the brain of cats sees something very different than
what these images would have us believe.

------
chatman
I have seen my cat find a mouse in a camouflaged garden even when the mouse
was not moving. Either this study is wrong or my cat is special.

~~~
TheCraiggers
I think you're missing a few possible scenarios.

First and foremost, cats have exceptional olfactory senses.

Second of all, the mouse was likely moving around before it noticed your cat
approaching, at which point it froze. (By that time, it was of course too
late.) Mice don't typically just sit in a garden, never moving.

~~~
acqq
Cats hear up to 60kHz. Those are super senses for us. Imagine what they can
hear by small animals -- the movements of the very small things in and on
mice, their breath...

------
peter303
I thought enhanced color vision developed for distinguishing plants. Primates
eat lots of plants nad have been trichromatic. Cats and dogs are mostly meat
eaters.

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akozak
It's an interesting trend to run a blog that drives attention to your startup.
The posts are becoming less and less relevant to the company too.

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elwell
When a cat looks at a human he sees a servant.

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ChikkaChiChi
Ran the link through Lynx and the results seemed more accurate:

[BED] [BED] [SCRATCHING POST] [BED] [POTTY] [BED] [BED] [BED]

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godzilla82
Forget about cats,how can we be sure that all humans see the same colors?

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jalanb
How come all those cats are nearly 6ft tall?

