Old Dogs' Minds Are Less Flexible but Their Memory Still Works

Source: JM Pearson Photography, licensed under CC BY-NC-ND 2.0

Everyone knows the old cliché, "You can't teach an old dog new tricks." Just don't expect a scientist who studies canine cognition to agree with that.

Even for a healthy older dog without canine cognitive dysfunction (the doggy version of Alzheimer's disease), the mind becomes less efficient with age. Numerous studies have shown that with age the learning process slows, and this is most noticeable in more difficult learning and problem-solving situations. A simple memory task that psychologists call matching to sample involves first showing the dog an item and then removing it and presenting two items, one of which is the same as the one he saw. The dog’s task is simply to pick out the item that he saw before. Older dogs do fine on this task, although they do a bit more poorly than younger dogs if you introduce a time delay between showing them the first item and then giving them the test. Apparently, the memory fades a little faster for the older dog in this situation.

Now let’s complicate the task. Suppose that instead of asking the dog to pick out the target that he saw before, we ask that the dog pick out the item that is new or different from the one that we showed him. This is called a non-matching to sample task, and older dogs do more poorly at this. Now if we also introduce a time delay between showing them the item and testing them in the non-matching to sample task, the older dogs have a really difficult time learning the rule.

In one series of studies, dogs first learned the difference between big and small objects. For instance, a dog might always be rewarded when he selected the larger of two objects. The shape of the objects is irrelevant; only the size counts. So on one trial, the dog might have to decide which of two balls is bigger, and on the next, which of two cans is larger, and so forth. Older dogs are a bit slower than young dogs at this task, but they make steady progress and do learn it. Once they’ve learned this and are reliably choosing the large item, the situation is reversed so that now the smaller object is always correct and rewarded. Obviously, any dog will make some errors at first, but young dogs quickly learn to switch over to the new rule to earn their rewards. Here, however, the older dog has serious problems.

Perseveration

When a variety of such memory tasks is analyzed, a general principle seems to emerge. It is not so much that older dogs have difficulty learning new material, but rather older dogs seem to have trouble inhibiting or suppressing material that they have learned. They stick with the old solution that they have learned for a much longer time. Psychologists would describe this as “perseveration,” by which they mean that there is a tendency for a memory or idea to persist, and for behaviors to be continued or repeated—even though it should be clear that the rules have changed or the old idea is no longer correct. In old dogs, earlier learning seems to be competing with newer learning and preventing them from acquiring new concepts and new solutions to tasks.

A real-world example of this occurred with my Cairn Terrier, Flint, who about 12 years of age at the time. One day on our morning walk, a cat skittered out from under a parked white van. Flint, being a terrier, gave chase, at least as far as the long leash would let him go. For the next two weeks, he persisted in checking under every light-colored vehicle parked along the street. He had learned that there might be a cat under a white vehicle and this idea perseverated in his mind for a long time, despite dozens of disconfirmations on each of his daily walks. My younger dog (at that time it was Wizard who was five years of age), joined the hunt the first few times but later he patiently stood aside and observed Flint’s continued excited searches under parked cars with some apparent puzzlement, and perhaps some disdain. He had quickly learned that the old idea that there might be a cat under any white vehicle was wrong.

The power of an old dog's early memories

Early memories are preserved better than later ones, however, and an old dog can still recall material that he learned when young. The old dog will even maintain the same likes and dislikes of people and places over the years. Stories of an old dog’s memories are common and often touching. One was told to me by Stephen Birch of Norfolk, Virginia who left his Black and Tan Coon Hound, Flannel, when he joined the army at the beginning of World War II. Flannel was 3 years old when Stephen left and he was nearly 10 years old when he returned. Stephen was sitting on his front porch stroking Flannel’s great-grandson and looking off into the distance as he recalled:

“Flannel was a neat dog. He got his name because his ears felt just like Flannel. He was my first coon hound and we spent a lot of time together. Whenever he thought that we would be going out for a walk, or to play, or just down to the garage where I worked, he would do this little dance where he would spin around, bouncing on his front feet, and then make this ‘Woo-woo’ sound. If I had been away from home for awhile he would do the same dance when I walked into the door. It wasn’t just being excited, ‘cause he would only do that for me. I used to think of it as his way of saying he liked me and expected me to do something nice for him.

“Anyway, it was around 1941 when I last saw him—before they sent me for training and then shipped me out to North Africa and later to Italy. When the war ended they started to send people back home, but I was assigned to take charge of a prisoner of war camp there, and that really delayed my release from the service. It was 1948 when I finally got to come back home.

“Mom and Dad knew that I was on my way, but not when I would arrive, so when I got to shore and was offered a ride home I thought that I would surprise them. When I walked up to the door and opened it there was Flannel. He was obviously a lot older then, with gray on his muzzle—although his ears still felt soft like flannel. He saw me, and it was just like no time had passed. He did his little dance and sounded off with that ‘Woo-woo’ song of his.

“Mom was in the kitchen and didn’t know I had walked in. When Flannel sang that little song she called out ‘What’s gotten into you Flannel. Steve’s not here yet but you act like you know that he’s coming.’ She later told me that Flannel had not done his dance or ‘Woo-woo’ in the whole time that I was gone. But he clearly remembered me, because he started doing it immediately after I came home, and he continued to do it every day for me until he died. That little ‘Woo-woo’ told me that I was home again and that someone remembered me—had missed me—and still loved me.”

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