Dog tricks
 

When I had my first Yorkie, Tiffany, I trained her to do all kinds of tricks. One of my favorites was putting all of her 20+ soft toys in a pile, and grabbing one, put it under her nose, and say to her, "Go find Froggie, or Duck, or whatever", and put in underneath the pile. She would go through the whole pile and pick out the right one 95% of the time. If she wasn't sure she got the right one, she would not bring it back to me, she would put it in her mouth, look up at me and wait for me to say "Good Girl!" If she did not get it right, I would say "No, fetch the froggie."
From what I understand, dogs are color blind, so how would she know which was the right toy? Some friends have said that it was because I had my scent on the one when I held it under her nose, but right after that, I touched all the other toys, when I put the froggie underneath. I have always wondered HOW she could always pick out the specific toy?

Are Dogs Really Color Blind?
Debunking an urban myth
By Pet Health Network Contributors
Reviewed by Dr. Celeste Clements, DVM, DACVIM on Monday, August 3, 2015

Dogs are not completely color blind since they have a dichromaticcolor perception. Unlike humans who have three different colorsensitive cone cells in their retina (red, green and blue) dogs have only two (yellow and blue)[3,4]. This does not mean that dogs can't see green or red objects!

If you think the answer is “yes,” think again! Modern science has answered this age-old question: Dogs can see color, but not in the same way that we do. The palette of colors they can see is limited in comparison to ours; it is also less vibrant.

Eyes have “rods” and “cones” to help identify color. Rods tell us how bright or dim something is (black or white) and cones help us identify color. Humans have three kinds of cones, which help detect yellow, violet, and green.

Dogs only have two types of cones, so they see orange, yellow, and green as yellow. Blue-green is seen as white and red looks as though it is brownish-black. While they can see blue, they can’t distinguish shades, especially as the color blue gets darker.