Are There Age-Related Changes in a Dog's Personality?

Aggressiveness, activity level, and trainability change as dogs age.

Posted Feb 20, 2019

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I was at a reception following a lecture presented to my psychology department by a visiting scholar when I was approached by one of my colleagues. She was excited because she had just read a scientific report by a team of researchers headed by Rodica Damian at the University of Houston. They had collected data on the personalities of a large group of people at age 16, and then tracked them down 50 years later, at age 66, to test their personalities again to see if there were any changes. What they found was that personality does change with age, often in ways that are easy to predict. According to their data, you can reasonably presume that a 66-year-old will be more conscientious, more agreeable, and more emotionally stable then he or she had been as an adolescent. What this colleague wanted to know is whether there were any similar studies which looked at age-related changes in a dog's personality.

The systematic investigation of the personality of dogs is relatively recent, without many studies published. At one point I had collected a large amount of personality data on more than 1000 dogs and that formed the basis of my book Why Does My Dog Act That Way. However, even though I looked at a lot of different variables, I did not collect data on how the canine personality changes with age. So I promised her that I would see if I could find any recent studies that might answer her question.

I did find a few published articles which suggested that life history and its owner's personality tend to shape the dog's personality, which, of course would lead to the conclusion that there should be age-related changes in personality. But most of the literature mentioned personality changes over the dog's lifespan only in brief comments. I was about to give up when I came across an article which has just been accepted for publication in the Journal of Research in Personality by William Chopik and Jonathan Weaver, both at Michigan State University.

This is a large study which gathered data on 1,681 dogs. Dog owners were asked to fill out a specially-designed questionnaire to describe the personality of their pets. It measured five dimensions of dog personality, none of which correspond to human personality traits. These traits were fearfulness, aggression toward people, aggression toward animals, activity or excitability, and responsiveness to training.

This was one of those pieces of research whose authors wanted to answer several major questions, so in the process they looked at a host of different variables. As is typical when an investigation casts a large net, the investigators were forced to use some highly complicated statistical analysis procedures which makes it difficult for the average reader without specific training to understand. However, embedded in their tables of results was the information my colleague was looking for.

Perhaps the most predictable outcome has to do with the activity and excitability levels in the dogs. As you might expect, younger dogs were more active and excitable than older dogs and the decrease in activity level occurred as a slow, steady, but consistent trend over the lifespan.

The two measures of aggression—toward people and toward other animals—both rose and fell in an age-related manner. For these aspects of canine personality, the trendlines indicated that there was a peak in aggression which was highest among 6-to-8-year-old dogs. Younger dogs, and older dogs, showed lower levels of aggression of either sort.

The finding which I found to be most surprising had to do with responsiveness to training. I think that most people who work with dogs feel that dogs are most trainable when they are young and that trainability weakens in older dogs. However, these new results suggest that a dog's responsiveness to training rises steadily from puppyhood and reaches a peak between 6 and 8 years before beginning to decline. That decline in the older years is no sharper than the rise in trainability observed from puppyhood to middle age. This suggests that you can, in fact, teach an old dog can new tricks and he will learn at the same rate as he did when he was a puppy.

There was no age-related change in the fearfulness of dogs over their lifespan; however, one interesting side observation about this personality trait was that dogs exposed to an obedience class tended to be less fearful overall.

These results are interesting; however, there is a limitation because the personality characteristics measured are not directly comparable to those that we see in humans. Since there is some evidence that dogs have at least four of the same major personality traits that humans do—extraversion, neuroticism, agreeableness, and openness—I suppose that it will be up to some other research group to see if those particular dimensions of personality, which do tend to change in humans as they age, also have age-related trends in dogs.

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Damian, R. I., Spengler, M., Sutu, A. & Roberts, B.W. (2018). Sixteen going on sixty-six: A longitudinal study of personality stability and change across 50 years. Journal of Personality and Social Psychology,

Coren, S. (2006). Why does my dog act that way? A complete guide to your dog’s personality. New York: Free Press (pp. i-xi, 1-288).

Chopik, W. J., & Weaver, J. R. (2019). Old dog, new tricks: Age differences in dog personality traits, associations with human personality traits, and links to important outcomes. Journal of Research in Personality,

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