Dogs can only see in black and white, so Im told. How does anyone know what colors a dog sees?

There are rods and cones inside your eye. People have 3 different types of cones, so we see three different types of color wavelengths, and their combos. We see red, green, and blue wavelengths of light, and their combinations. This is how we see the rainbow.
Dogs don't have these 3 types of cones, they only have 2, the green and blue ones. They don't see red, so they can't see things like purple, just blue, green, and a touch of yellow.
The colors we see are different than the colors in your art class, the color of a light depends on its wavelength, and that is what we see.
There are other animals that have other types of cones in their eyes, so they see tons of different things. The mantis shrimp, for instance, has 16 different types of cones, so they see 16 different wavelengths of light.

Not true. They can see a few muted shades of color but its limited. Google on "what a dog sees as far as colors". Cats can see more shades then dogs and birds can see more shades then people!

No they do NOT "only see in black and white"

Dogs lack the color receptors for red.. So they see shades of blue, yellow and green.
They also have fewer color receptors than we do, so the colors are not as vivid to dogs as they are to us.

You have been misinformed.

Dogs can see all the colours a human can except they suffer from colour blindness in the same way some humans do.

If you research this it will be confirmed.

No..... https://www.psychologytoday.com/gb/blog/canine-corner/200810/can-dogs-see-colors

Google it.
Dogs can see some shade of blue and yellow.
There is actually a sprectrum you can look up that shows the range that humans see and the range that dogs see.

they can see faded colors mostly earth tones. The eyes have rods and cone they are color receptors. Birds and fish have them, dogs cats most ground dwelling mammals have limited color vision due to the lack of these rods and cones.You can't google this?

Not true.

I guess someone did some experiments involving treats hidden in containers with specific colours...

Dogs may see fewer colours than we do, but they smell a lot more smells

scientists know.