My brother asked me the other night how do 'they' know dogs can see in color. "I don't know."It's pretty easy to test. Make three doors, one red, one green, and one blue, that can be switched left, right, and center. Put food behind the red door, consistently, and no food behind the other doors. If the dog can see color, he will be able to predict which door has the food. If not, he will continue to guess at random.