How do scientists know that animals see in black and white?

Question

if animals cant talk how could they possibly know!!

Answer 1

teach your dog to piss on the blue carpet and then you'll know

Answer 2

As some of the answerers have stated the ability to see colors varies from species to species. Besides examining the eyes for structures known to give color vision in humans, experiments can be done to train animals to recognize items by color. For instance:

You can train many animals (dogs, cats, chickens, monkeys, etc.) to push a button in exchange for a reward. Then you can train them to select one of two buttons where they get their reward only if they select the "right" one. Then you could place a colored card next each button and see if the animal can learn to choose a button based on color. If the animals easily learns to select, say a red card over a blue one then it is possible to conclude that it can distinguish between red and blue. You can then extend the experiment to other pairs of colors. An animal which fails to learn to select any color over another is probably color blind and sees the world like a black and white movie. This experiment would have to be designed carefully to make sure that the animal is not seeing or sensing something besides color such as brightness or smell.

But even if an animal can distinguish a wide range of colors there is no way of telling whether it sees the world the same way that humans do. For that matter it is not really possible to know if two humans with normal vision see the world in the same way since we can't plug into each other's minds. What I see as green and what you see as green may be two completely different experiences! We only agree on color because we both sort a group of colored objects the same way.

Answer 3

The 2 types of photoreceptor cells... Rods and cones.... they allow animals to see colour and light. When a scientist dissects a certain animals eye they can see how many rods and cones they have... cones detect colour, so if an animal has no cones they dont see color as well as creatures with more cones.. its not that they see in "black and white" (thats not what colour blind means) its just that their eyes do not have a sufficient number of cones to detect all the colours that an animal with more cones can. Here is an interesting article that explains how dogs see colour and how we know approximately what colours they see... http://www.50connect.co.uk/index.asp?main=http%3A//www.50connect.co.uk/50c/articlepages/pets_index.asp%3Fsc%3Ddogs%26aID%3D4184

Excerpt from Wikipedia...
A photoreceptor, or photoreceptor cell, is a specialized type of neuron found in the eye's retina that is capable of phototransduction. More specfically, the photoreceptor sends signals to other neurons by a change in its membrane potential when it absorbs photons. Eventually, this information will be used by the visual system to form a complete representation of the visual world. Described here is a vertebrate photoreceptor. Invertebrate photoreceptor in organisms such as insects and mollusks are different in both their morphological organization and their underlying biochemical pathways.

They are responsible for transducing, or converting, light into nerve signals that can be ultimately transmitted to the brain via the optic nerve. In vertebrates, there are two types of photoreceptor cells: rods and cones. Cones are adapted to detect colors, and function well in bright light; rods are more sensitive, but do not detect color well, being adapted for low light. The human retina contains about 125 million rod cells and 6 million cone cells. The number and ratio of rods to cones varies among animals, dependent on whether the animal is primarily diurnal or nocturnal. Certain owls have a tremendous number of rods in their retinas — the eyes of the tawny owl are approximately 100 times more sensitive at night than those of humans.[1]

Answer 4

By counting the number of rods and cones in an animals dissected eye. The number determines if the animal can see color. However that is by using the known human eye for a base.

Answer 5

Experiments and common sense.
I don't know exactly how they do it, but I can imagine that they show a lot of different things of different color and see how animals react.
That's just a simple way to put it.

Answer 6

It has to do with the amount of rods and cones in their eyes. Quite fascinating actually...but I believe there are some that still debate that some animals can see in color.

Answer 7

There are special cells in the eyes, some see color (cones) and some see light or black and white (rods). If a species has rods and cones like humans they see color, if they only have rods like a dog they see black and white.

Answer 8

I was watching the Discovery channel and they showed that dogs can see in colors, not all colors, but more than black and white.

Answer 9

Color studies. Animal science.

Answer 10

I agree -- my cat LOVES anything red. She notices it right away.

Red string, red paper ... she will always choose the red items over anything else you offer her.

Answer 11

I always wanted to know the answer to this myself.