Cody seems to go for his blue squeakies, prefers yellow tennis balls to any other and how funny!! goes for red!!! But not always in a good way. I had a red jacket he decided to grab off me and tear (never did that before)..also did not like a red tshirt I had but liked his red plaid pillow. We try to test him and blue wins out. How do they know for sure what colors they see???? I heard, black and white only, then I read that it's reds and blues.. how would anyone know for sure???? Hmmm..curiosity!