It matters to dog training.

The basic answer is easy. Dogs see blue and yellow. Their ability to see detail is rather poor. Some clients fire back that this seems absurd. Dogs can clearly see a squirrel flicking its tail behind a veil of leaves, half a block away. (Critical thinkers are literally the best clients. I’m not complaining.)

Those dogs will also walk right past a stationary squirrel, completely missing it. They really struggle to find that big treat, sitting stationary on the ground.

Dogs easily see a moving squirrel. Dogs have difficulty seeing a stationary one. Something is up. If they don’t see what we see, then every training request should ask if dogs can actually see the task. Animals can only do what they are physically capable of doing. This varies from one species to another.

The “Nuts and Bolts” of Vision:

Light enters the eye and a 2D image is cast on the retina. Memory in the eye processes the information. It is then sent to the brain to be reconstructed into a 3D image. In order to do this, we have two main types of cells. Rods (Value or Greyscale) and Cones (Colour). I always remember the two “C” words go together. There are a couple theories of colour. They aren’t too important to know, except that if dogs can’t see red, they cannot see green, orange, or purple either. Warm yellows and warm violets are also at issue. Warm colours are made by adding red. If you cannot see red, then these colours cannot be seen in full technicolour glory. It’s just yellow and blue.

Colour: It’s not as important as you think

Have you ever seen art where the artist uses odd skin tones? Have you ever noticed that they smudge areas and yet it still “works?” Alpay Efe uses a wide range of hues when painting human skin, including greens, reds, blues, and violets. It still works. How is this possible?

Colour is helpful, but not essential. Values do matter. This is why movies and photos in black and white “work.” They have the critical information, the greyscale. Greyscale helps viewers get a read. The most colourful photo is poor and difficult to read if the values are wrong. Both of the following images show a sphere. The light must be to the top right (because the shadow is bottom left.) The values tell us this object is round.

Colour provides different information. It tells us that the ground is possibly grass and not a wooden table. It’s likely outside because the sky is blue. It might not be, but it informs the interpretation. Take colour away and it’s harder to understand ambiguous items. Is it a cue ball on a billiard table or a giant sphere sculpture on a lawn? No clue. Not enough information to tell. Information about texture might help. We know that this is not a golf ball as it has no dimples. All this information is processed inside the brain, subconsciously.

Colour can also tell us things such as the time of day or how close one object is to another. Looking again at our grey/white sphere, looking closely, it is not grey at all. The top right is yellow and “yellow-greys”. The top left is blue and blue-grey. The bottom left is green and green-grey. Why? Because light bounces. As it does it carries colour with it. Traces of the colour of light are left along the way. If that ball was floating above the grass, it would not take on the green bounced light that had previously hit the grass. Our brains make these judgments behind the scenes, without us really being aware that it is happening.

Colour can help the brain make decisions. Imagine a box and some crayons. In colour, it is easy to see that the box hides at least two crayons. One is red and the other is green. They are partially blocked by a violet box. Converting this to black and white makes both colours look the same. It could be one longer crayon. Despite there being 3 colours, there is only ONE VALUE. Colour makes visual information easier to understand.

The way I like to think of it is this. Value gives one set of information. Colour provides a second. It is a two-part system. Each serves as a backup plan for the other. When colours are confusing, the value cleans it up and vice versa. Brains frequently have a backup plan.

Colour and value work TOGETHER. Colour is on one shoulder. Value is on the other side. Which leads to a pretty significant effect that artists know very well. Take a look at the two strips of colour. These are yellow and blue, “dog vision” colours. They range from very light, watery versions up toward “out of the tube full intensity.” You cannot get “more intensely yellow” and you cannot get “more intense blue.” You can only add black from this point, which would make it dull. Adding black does not make a colour more vibrant.

Converting it to black and white shows the values or greyscale. Filters aren’t exactly spot on, but often they are good enough for this point. Remember that the darkest yellow and blue are direct, “out of the tube.” When we look at these strips in black and white, a crazy result happens. The most intense yellow is lighter than a pale light blue. Blue can become dark and remain high chroma blue. Yellow cannot. It’s counter-intuitive.

Taking this one step further, I did an interpretation of sugar maple leaves “through a dog’s eye.” The blue areas (with their huge range) read well. The yellows in the background, especially when viewed in black and white, simply disappear. Adding a little light cerulean blue isn’t going to help much because light blue is the same value as our problematic yellows. The light blue also dissipates, merges, and vanishes into a cacophony of colours that fall into the same range. It becomes a perceptual nightmare for the brain to sort. (Artists do this on purpose. If you’re watching Alpay Efe’s videos after reading this blog, I’m pretty sure that’s why he smudges his paintings. He’s blurring the areas that he wants the brain to “skip over” in favour of high-contrast detailed areas (like the eyes) He’s using artist Jedi mind tricks to “force” your eye to look at what he wants you to look at. Creepy that it can be done to you and yet oh so fun. His video on the beauty of imperfection is good regardless of your interest in art. As I’m new to art, perhaps I’m wrong about why he does it. But pretty sure that’s it.

It bears repeating. Colour is not everything. Color means nothing without corresponding value changes. Dogs rely on values more than we do.


A dog’s eye has a coating that bounces additional light onto sensitive receptors. This coating is what makes eyes “glow” in photos. It aids in night vision and in the perception of motion. Unfortunately, the cost is a loss of detail.

Natural selection has favoured dogs that can easily see “things that move.” The colour of the critter is irrelevant. Brown squirrel, black squirrel, red squirrel, or white squirrel. It’s all just squirrel. Information from colour adds little benefit. Evolution favoured dogs that had the ability to see motion because the ability to detect motion results in catching more squirrels

Struggling to see details is especially tricky when the atmosphere blends with the objects found within it. Dogs may struggle to see someone approaching, especially if the person’s clothing blends in with the environment. It matters not if the person is wearing a red coat and the human can see it mile away. Dogs don’t see red. Dogs can be “suddenly surprised” over things we saw several minutes earlier.

Think of dog vision as “SOMETHING moved…there.” The dog needs to decide if it’s food or foe and where the food or foe is at the moment.

Dog vision isn’t a deficit. It’s a trade-off. Neither is better than the other. They both work Dogs evolved an amazing sense of smell and the ability to detect minute movements. Humans can see detail, which helps in fine motor movements, movements that require detailed visual input. Different strokes for different species.

Application to Training

  • “Dogs don’t look at nothing.” Just because we, the humans, cannot see what distracted our dogs, it does not mean that nothing was there. Distracted by nothing is a phrase that probably shouldn’t exist in dog training. The dog was distracted by something that we, the human, did not discern. Assume the dog saw “something.
  • Choose toy colours wisely. If you regularly cannot find your dog’s ball in the grass, buy red toys. You’ll see it better. If your dog struggles to find a ball in dark green grass, buy bright yellow toys. If your grass is yellow and dormant, buy dark blue toys. Amplify the contrast between dark and light and choose a colour that your dog can actually see. (Light ball on dark grass. Dark ball on light grass).
  • Changes in tone can set off reactive dogs. For example, white face masks were common during Covid. At one point, black masks became available. Dogs that recognized me while I was wearing a white mask failed to recognize me when I wore a black mask. A human would recognize both as “a mask.” A dog sees that light skin with a light mask changed to “Half her face went dark. Stranger – Danger!” Similarly, putting on a hat or a cloak is sufficient for many dogs to assume a “new person.” You can use this in rehabilitation training to your advantage. Keep decoys at a distance, but have them change their silhouette or appearance. One decoy can take on many appearances with costume changes if the dog is at a distance. (You don’t need 100 close personal friends to train your dog. You just need one or two who are willing to do realistic costume changes.). Warning: Do not do surprise appearance changes close to the decoy until the dog is HAPPY (not good, HAPPY) at longer distances. If you bring dogs too close, too fast, and surprise them, someone is going to get bitten. It’s dangerous, completely not required and fully trainer error.
  • Make your own equipment, but choose your colours wisely. Professional gear is usually blue and yellow for a very good reason. Use high contrast and colours that your dog can actually see.
  • Building your dog’s tolerance to distractions, such as squirrels? Many dogs notice small movements, such as one leaf out of sync with the others. Dogs are pretty clever and realize that when leaves move, there is likely to be a critter nearby. Their vision system is so good at motion perception that they don’t just see the squirrel first. They see the details that tell them a squirrel is near. This is good for distraction work. Keep your focus on your dog because when they notice something, something is likely there. Do not dismiss this early warning. Humans can, if they are paying attention, be prepared to reinforce their dog or cue their dog after a notice and before a reaction.
  • Even if you don’t have a dog, and are just curious, it’s an interesting experience to realize that we overlook more than we perceive. Artists see the world differently because stop to look. They look deeply, critically, curiously. When you stop to smell the flowers, look at them – really look at them. You may be surprised at what you’ve been missing.

Full disclosure: Violet was used in the dog vision painting. Yellow mixed with violet makes neutral grey which is why artists often use violet when shading yellow. Yellow mixed with black generally looks like, a “rotten banana.” It’s not pretty. Dogs do see grey, so the addition of violet, in watercolour, creates a colour that they can see. This is an interpretation of what dog vision could look like. Pinning down the value changes in dog vision is somewhat tricky.