Figure 2.

How rats see the world. Rats (and mice) are very short-sighted and do not have the receptors for the color red. While they have the receptors for other colors, they do not naturally pay attention to them. Thus, what they see is very different from what we see, which will affect how they will perceive certain visual cues used in experiments. Top, Left to right, what a human would see, a pigmented rat (e.g., Lister Hooded or Long–Evans strains) would see and what an albino rat would see. Taken from http://www.ratbehavior.org/RatVision.htm.