麻豆传媒

Does your pet have a personality? 鈥楬ow can you even ask?鈥� snap the doting owners. Others scoff at the idea. After years among hyenas, dogs and humans, Sam Gosling tells Liz Else what all the fuss is all about.

Why are people hostile to the idea of animals having personalities?

I should point out that I came to the area assuming that animals didn鈥檛 have personalities, so I was myself 鈥渃onverted鈥�. I trained as a personality psychologist for humans and I was trying to understand human personality by looking at a case where I thought personality clearly didn鈥檛 exist 鈥� animals. But as a believer in the theory of evolution I found it hard to maintain that argument. Darwin wrote about emotional states in animals so the idea had important beginnings. And early psychologists such as Pavlov looked at personality in non-human animals.

But it suddenly went out of favour, largely due to a fear of anthropomorphism, but also because of the idea that this just wasn鈥檛 the kind of stuff serious scientists should be concerning themselves with. When I started doing this research as a graduate student, one colleague said it was a bit 鈥済oofy鈥� to talk about personality in animals, and another said I was bringing psychology into disrepute by studying something that was so trivial. But I think we now have good evidence that personality descriptions of animals are not mere anthropomorphic projections.

How do you define or recognise personality in an animal?

There are two ways to think about it. The first is similar to the way we think about personality in humans 鈥� that is, we compare behavioural trends among individuals within a species. The second way is to take a cross-species framework, where we might say something like dogs are friendlier than black mambas. Many personality traits are very related to problems of adaptation, so you would expect some cross-species similarities.

Such as?

Like humans and non-human primates, many other animals are concerned with two tasks. One is getting ahead, dominance, and the other is getting along with others, sociability. You want to promote yourself and end up with a lot of offspring, but you also want to get along if you are a social species. There is also a lot of cross-species evidence for nervousness, fearfulness or anxiety. Clearly it makes sense for all species to demonstrate some levels of fearfulness just to stay alive.

And what about boldness? There are certain environments where it might be adaptive to be shy and others where it might be adaptive to be bold. If you鈥檙e a fish living in a brook where you鈥檙e not subject to aerial predation then it is probably pretty good to be bold 鈥� you can go out, find more food or mates and so on. If you are subject to aerial predation, then the shy fish will do better because they won鈥檛 go out and they won鈥檛 get eaten.

What about curiosity, which we always think of as a very human trait?

Curiosity is a great example. It makes sense if you belong to a species that lives in a rapidly changing environment, with big seasonal variation, that you need to be curious. You鈥檇 need to be inventive about where to find food. On the other hand, for a sheep living in a very stable, plentiful environment, curiosity isn鈥檛 so important. If there is plenty of grass all year, why risk getting into trouble by eating mushrooms?

What about your own work? How do you set out to measure personality?

I鈥檝e done a number of studies. My first major study was on 34 spotted hyenas housed at a field station at Berkeley. The first task was to make sure the traits we attribute to animals actually reflect what the animals are like: if we describe Fido as 鈥渇riendly鈥�, how do we know that we鈥檙e really talking about Fido rather than just attributing properties to Fido?

One way of doing it is to get people to rate Fido and Rover and see if they all agree that Fido is more friendly than Rover. So I recruited a bunch of people who knew the hyenas well and asked them to rate their personalities. I used personality ratings much as I would if I were doing human personality ratings. We found very strong levels of agreement among the observers which suggested that they could really discriminate between the animals, and this was the first real sign that there was 鈥渟omething鈥� there.

And recently you鈥檝e come up with a 鈥減ersonality test鈥� for pet dogs鈥�

Dogs are good to study because they are a part of everyday human life, so many people are familiar with their behavioural repertoire, which allows them to serve as judges. Again we compared what the owner said about the dog with what other people said about the dog, but this time we did an additional behavioural test.

We found that these ratings of dogs predicted their behaviour, which is as good as you get. That is what we mean by personality: for our statement saying Fido is friendly to mean anything, it has to predict Fido鈥檚 friendliness-related behaviour, and this study showed it did.

Are there any personality traits that only humans or non-human primates have?

Yes, conscientiousness. In our cross-species analyses we haven鈥檛 found any evidence for conscientiousness as a separate dimension in any other species other than humans and chimpanzees. Conscientiousness is related to the ability to focus on a task, not to get distracted, and to delay gratification. It requires inhibitory mechanisms which lead to internal thoughts like: 鈥淚鈥檓 not going to lash out at that chimpanzee wandering by me because if I do I鈥檓 going to get into trouble.鈥� These are the sorts of things that are associated with the most recently developed frontal cortex part of the brain, which is most developed in humans and chimpanzees.

Could there be personality traits that we cannot imagine?

Yes. There may be other dimensions which we just can鈥檛 detect or even understand. Who knows 鈥� given that we don鈥檛 have a very strong sense of smell maybe there are all kind of personality dimensions that we cannot even make sense of in the smell domain or some subtleties of social hierarchy in certain social systems that we cannot understand. What we can say is that there seem to be certain personality dimensions that cut across an awful lot of different taxa, probably because these are fundamental, and as each taxon evolves into its own niche under its own evolutionary pressures, different personality dimensions emerge.

Could you use animals as models for human personality?

Yes. You can do things with animal studies that you cannot do with humans 鈥� not all of these are nasty stuff like sticking things in them. One of the most powerful experiments for teasing apart biological and environmental factors are cross-fostering studies where infants are swapped at birth so you have a mother bringing up someone else鈥檚 baby. You can look at this baby鈥檚 personality and see if it more closely resembles its biological mother or foster mother. One study by Steve Suomi has shown that it is the biological mother that predicts the anxiety levels of the infant, suggesting that this has a biological cause.