Dogs

       We all know dogs are color blind, so does that mean their vision is also poor? If dogs don’t have good eyesight, can they quickly capture prey relying only on their sense of smell, hearing, and touch?

       In fact, dogs’ vision is indeed not very good. Their eye accommodation ability is only one-fifth of that of humans. For fixed targets, dogs can see up to 50 meters at the farthest, but for moving targets, their capture range can reach 1000 meters. Trained shepherd dogs are said to see people from 1500 meters away.

       Besides having good distance vision, dogs also have a much wider field of view compared to humans. A dog’s monocular horizontal field of view is 100°-125°, upper field of view is 50°-70°, lower field of view is 30°-60°, and binocularity can reach 250°-300°, whereas humans have only about 180° field of view.

       Additionally, dogs’ vision in darkness is much better than humans’, thanks to many more cone cells and rod cells sensitive to dim light in their eyes. Therefore, if a dog suddenly barks in the dark, it is very likely they have seen something that you cannot see.

       As for the common concern "dogs are color blind, so how do they guide blind people across the street as guide dogs?" they have their own ways to solve this. Although dogs cannot distinguish colors clearly, they can judge the traffic light indications by changes in brightness and position of the lights. More importantly, dogs can also rely on the traffic light’s sound signals to help themselves identify the state of the signal lights.