The Nature of a Dog's Eye Can Make Problem-Solving Difficult

A dog's eye is less efficient than a human's when extracting information

Posted Apr 12, 2017

Creative Commons License CC0
Source: Creative Commons License CC0

The man standing beside the young black Labrador Retriever looked slightly frustrated. He held up a bright red rubber bumper, which is typically used to train dogs to retrieve and explained to me "I'm trying to get her to retrieve this quickly. When she can see me toss it and she gets to watch where it falls she does great. But if I have her facing in the opposite direction so that she can't see the actual throw, then when I send her out to find it she'll often run right past it as though she doesn't even see that it's there."

The problem that this dog owner is facing is not that his dog can't figure out what is wanted of her, but rather she is looking at the world through the eyes of a dog. Although the dog's eye looks very similar to the human eye, the dog's visual capacities are much more limited than ours are. To begin with, dogs have limited color vision (click here or click here for more about that). Part of the problem which this dog was having is based on the fact that for dogs the red or orange colors (like in the retrieving bumper) look virtually the same as the color green (like the high grass on the field that the bumper was being tossed into). You can see that in the figure below.

SC Psychological Enterprises Ltd.
Source: SC Psychological Enterprises Ltd.

So suppose you were setting up a problem-solving situation in which the dog had to find a red flower surrounded by green foliage. The dog's limited color vision would make this a more difficult task as you can see below.

SC Psychological Enterprises Ltd.
Source: SC Psychological Enterprises Ltd.

But color is not the only problem that a dog faces relative to a human when trying to solve problems based on visual information alone. In addition to limited color processing, there are two other problems. First, dogs don't discriminate levels of brightness as well as humans so that their world appears somewhat washed out and there appears to be less contrast between areas of different brightness as you can see here.

SC Psychological Enterprises Ltd.
Source: SC Psychological Enterprises Ltd.

Much more importantly the visual acuity of dogs is more limited than that of people. Dogs are relatively farsighted, meaning that distant objects are most clearly seen. Objects which are close, or in the middle range (nearer than around 10 feet or so) will appear to be blurry in comparison to what a human sees. That will affect the visual image as you can see below.

SC Psychological Enterprises Ltd.
Source: SC Psychological Enterprises Ltd.

 If you put all of that together you will find that dogs are losing a lot of important information that they could use to solve problems simply due to the limits on their visual abilities. Let's return to the example that we started with, namely "Find the red flower". For a human with normal vision, this is a trivial problem. However given the nature of canine vision, when we combine the dogs' limitations on color vision, brightness discrimination and visual acuity, the difficulty level of this problem rises dramatically, becoming something more like a hidden object puzzle, reminiscent of the "Where's Waldo?" puzzles which were popular a few years back. You can see that when we compare normal human vision to normal canine vision (with all three forms of visual processing limitations included) and now I ask "Where's the Flower?".

SC Psychological Enterprises Ltd.
Source: SC Psychological Enterprises Ltd.

Just how much a dog's normal visual limits can interfere with its problem-solving abilities was recently demonstrated by it team of researchers headed by Péter Pongrácz of the Department of Ethology at Eötvös Loránd University, in Budapest, Hungary. While it would be nice to run an experiment in which you corrected all of the dog's visual limitations and then saw how much better it performed in various problem-solving and information processing tasks, that can't be done. So instead this team of investigators adopted the opposite strategy and processed images to look like they would appear to a dog (much as I have done above) and then presented these modified images to human beings to see how efficient they were in extracting information.

Specifically, 50 test subjects were provided with photographs which showed a young woman who was indicating whether an object was located to her left or her right. The photographs could either be unaltered or processed so that only the information available to a dog would be available to the person viewing them. The woman used three different types of directional signals to indicate which side was the correct one (supposedly the side where a ball could be found). One signal was quite large, namely pointing with an extended arm. The next type of signal involved the person turning her head in the direction of the object. And finally, the most subtle signal was one in which the model simply turned her eyes in the direction of the object without turning her head or body.

The results were exactly as these researchers expected. When presented with the normal, unaltered, photographs the subjects were virtually perfect in their ability to figure out which direction was being indicated. However, when presented with the photographs showing the world as the dog would see it many errors began to creep in. As the signal became more subtle, moving from the broad signal involving a pointing arm, down through the head turn and finally just involving the eyes turning to one side or the other, the error rate went up significantly. Overall the human subjects were most prone to making errors when asked to detect the correct side based on the direction of gaze alone if all that they had available was the view that a typical dog's vision provides.

So if you are trying to train your dog to make some sort of discrimination and your pet is having difficulty with the task, it is important to assess the situation to see if the dogs visual abilities might be placing a limitation on the amount of information that your pet can process. Perhaps broader signals, especially those involving movement, or using items with large brightness differences (rather than color distinctions) might help to solve the problem.

I suppose at this point some of you are wondering, "If dogs can't easily discriminate the red of a dog toy or retrieving an object from the green of the grass covered surface that it is being tossed upon, why are the most popular colors for dog toys either red or reddish orange?" The answer to that is simple. Red is easily discriminated by people, and it is a human, not a dog, who is buying the toy.

Stanley Coren is the author of many books including: Gods, Ghosts and Black Dogs; The Wisdom of Dogs; Do Dogs Dream? Born to Bark; The Modern Dog; Why Do Dogs Have Wet Noses? The Pawprints of History; How Dogs Think; How To Speak Dog; Why We Love the Dogs We Do; What Do Dogs Know? The Intelligence of Dogs; Why Does My Dog Act That Way? Understanding Dogs for Dummies; Sleep Thieves; The Left-hander Syndrome

Copyright SC Psychological Enterprises Ltd. May not be reprinted or reposted without permission

References

Péter Pongrácz, Vera Ujvári, Tamás Faragó, Ádám Miklósi, András Péter (2017). Do you see what I see? The difference between dog and human visual perception may affect the outcome of experiments.Behavioural Processes, http://dx.doi.org/10.1016/j.beproc.2017.04.002

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