The Sense of Sight

[xXxAhmedTarekxXx]

1:12 Ouch !!

[maria80153]

im going to fail my optics final

[falixxxxx]

Cats dogs and many other mammals can see better than we can because they have a reflective layer in the back of their eyes called a tapetum lucidum.

Not because they "open up further" as the video states.

[Dirtfire]

@falixxxxx you're right that the tapetum lucidum (which I'd never have been able to spell if you hadn't spelled it) is part of the reason why cats and other animals have great night-vision. The bigger reason is that they have many more rods vs cones than we humans do. The video's description of rods and cones is correct.

cats and dogs have 2 types of cones (blue and greenish/yellowish) whereas humans have a third type -red. Cats can't differentiate red/green/yellow and have poor day-vision.

[Dirtfire]

@Dirtfire many birds are just the opposite. They have far more cones vs. rods than we do, giving, say, an eagle far superior day-vision. They even have a 4th type of cone that senses ultraviolet light (and thus any mixture of it and other colors), giving them the ability to see far more colors that are invisible to us.

Their night-vision is far worse than ours, but then they don't need to see at night --unless we're talking about night-owls, which again have far more rods vs. cones than we do.

[midnight613toker]

you know if you wear lens (well prisms) that make the everything appear upside down, after a week your brain will switch it right side up.. thats sweet.. but some guys had trouble getting it to switch back after they took the prisms off

[dsalimander]

l2volume

[mrdwinfield]

Actaully that's not quite true. The image appears upside down because as the light passes through the lens, the tragectory of thelight is changed, so the image appears upside down on the retina. Once the image is processed and and sent down the optic nerve, the signal from one half of the eyes is crossed over at the optic chiasma, and then rejoins the signal from the other side of the eyes before it is sent to the back of the brain where it is interpreted.

[win2rgirl]

why is the image reflected upside down?

[xTPTxOCELOT]

because it wasn't designed by a divine being!

[JackHL]

@xTPTxOCELOT Are you kidding? Do you really think this happened by chance? The eye alone could not have been chance, not to mention every other aspect of the human body and nature.

Do you think that every living thing started out with one eye and then evolved to two eyes because they didn't have depth perception? It was Designed! Obviously.

Evolutionists make me laugh, getting the theory of evolution all mixed up with the query on the origin of man. They are two separate subjects. Peace

[egokick]

@JackHL your argument is that the eye is improbable to have came about naturally due to its complexity. God is infinitely more complex than an eye, therefore god is infinitely more improbable to exist than the eye.

People need not waste their time arguing about the specifics of evolution if they are to take 5 seconds and examine the utter ridiculousness of your argument. There may be valid criticisms of evolution out there, but shouting hurr durr, god did it, is not one of them.

[JackHL]

@egokick Both evolution and Intelligent design are equally unprovable. Evolution is a very young theory with a few natural existences that could point to it's validity if you try hard enough. Likewise, Intelligent Design is a very OLD theory with a few natural existences that could point to it's validity if you try hard enough. Your right about the pointlessness of argument despite your bias. Either way, the world will be a better place if we focus on the future, the past is beyond our reach.

[egokick]

@JackHL You have miss understood what I was saying, I am not trying to claim that theories should not compete and that debate/argument is pointless (quite the opposite), I am merely claiming that ID makes such contradictory claims on the surface with errors like the one I pointed out above, that it is unnecessary to delve in to the details in order to discount ID as a valid theory (because it is contradictory). The age of the two theories is also completely irrelevant as to their truth value.

[senorpajarito]

@JackHL There is a huge body of evidence that demonstrates the validity of natural selection and the evolution of organisms from unicellular to multicellular. Sedimentary rock is layed down over time. The older the layer, the deeper in the ground it is. We have evidence of fossilized single celled organisms in the deep layers, and each layer going up (getting younger) is inhabited by more and more complex multicullular organisms. The fossil record, while containing some gaps, is very clear.

[satanHchrist]

because the light beams cross and it appears upside down. when your first born you see everything upsidedown, but your brain teaches itself to flip it over.

[pradheepan]

@win2rgirl :- it is because the lens form upside dowm image and l8r our brain modifies it to normal

[wentoer]

i really couldnt give a fuck...

[hyac3inth]

momorgoth,

And do you know that it has been found by scientists that some animals other than humans see MORE wavelengths of light than humans, therefore having better eyesight than humans?

Humans have not inherited the "best" or "ultimate" of any anatomical/physiological phenotype, just whatever genes have allowed survival long enough to reproduce.

[hyac3inth]

momorgoth,

you are being silly.

People around you whom you trust have told you that they can't since you were bitty.

They weren't intentionally lying; instead, they were just telling you either

- what they had been told (by people who were just guessing or from the scientific info available at that time

OR

- what they thought from their own "common sense", which is not always reliable

There've been numerous scientific studies that show that dogs & cats have color vision.

[FishelKANI]

hyac3inth

you are being retarded

People around you whom you trust have told you that you can make a coherent sentence.

They weren't intentionally lying; instead, they were just keeping you from the fact that YOU ARE A DUMB-ASS

RESPONDING TO A TROLLER FAIL

[hyac3inth]

Name-calling is not a valid argument for a point of view.

How about if you post links to evidence that supports your point of view, and I do he same?

[hya3cinth]

the video claims:

"dogs and cats experience a black and white world"

Wrong. They have cones as well as rods, so they do see colors.

[momorgoth]

No they can't.

[vuot23]

this was well explained!...i get it now.

[reesedykers]

Explains clearly how rods & cones work to help us see.

[singstar49]

i like learning about the human eye and this was was a fun and easy way

[ichsuka]

interesting anyway, we should know how our own eyes work

[SauronsEye]

I can't SEE the point of this video. It ends abruptly.