Dogs have been with us for thousands of years. They exist because of people and until relatively recently we knew so little about them. Some of the things we "knew" have been disproven and many other things we're only just beginning to learn. The statement about dogs being colour blind is widely known and repeated but it's not entirely accurate.
Light travels in different wave lengths, with different lengths being perceived as different colours. The eye is an organ which acts as a net- it can "catch" the light, then receptors in the eye process the waves and send the information to the central processing unit (brain) to make sense of it. This is what we can actually see.
In the eye there are rods; responsible for vision at low light levels, and cones; they sort out the colours. Humans have more cones so can see more colours than dogs. Dogs have more rods and less cones - they can see some colours but are able to see much better at lower light levels than people can.
If you compare old movies to new ones, the pictures don't compare. You can see the gaps in each frame, a bit like a flip book. Nowadays the technology has come so far that we can't see the frames, they are as fast or faster than our eyes can detect, which results in a smooth flowing picture for us to watch. Eyes work like this too. For dogs, their flicker rate is higher than humans. What does that mean?
They see more of the world sooner than we do.
Let that sink in. Their lightening fast reactions are because they have seen more of the world faster.
Sound also travels in waves but it is slower than light. This is why you will see an airplane in the sky and then hear it, or it seems like the sound is "following" the plane.
Depending on how athletic your dog is will have an effect on reactions however even small companion breeds are usually stronger and faster than humans in relation to their size. Combine that with their ability to detect and react to movement sooner and we can start to appreciate perhaps only saying "Fluffy come" isn't the best way to get a speedy recall.
Here are two examples to compare (from pethelpful.com and barnyardveterinaryservice.com) - there are plenty more online to check out!
