Most people who choose dogs seem to have some physical similarity with them. High heeled coiffured ladies with long legged, high stepping dogs, overweight people with plumper dogs, shaggy haired master and dog. Sadahiko Nakajima is a psychologist at Japan’s Kwansei Gakuin University who has researched not just the notion that humans and their pet dogs look alike, but also why that is so.

In 2009 Nakajima showed how people were able to match dogs and their owners simply by looking at photographs of their faces. This is one of the many experiments done that reinforce the popular belief that dog and owner have a physical resemblance to each other. The next step was to understand why. Nakajima conducted another experiment, the results of which were published in the journal Anthrozoos.

He found that the reason lay in the eyes.

500 people were shown two sets of photographs. One set showed pictures of real dog-owner pairs, while the other set had random pairings of people and dogs. The participants were shown five sets of pictures where different organs were masked: no-mask (in which the human’s and the dog’s faces were unobstructed), eye-mask (the human’s eyes were blacked out), mouth-mask (the human’s mouth was blacked out), dogeye-mask (the dog’s eyes were blacked out), and eye-only (where just the eyes of the human and the dog could be seen).

The participants were then asked to select the dog-owner pairs that physically resembled each other. As in Nakajima’s 2009 experiment, 80 per cent participants who were shown the unobstructed photos correctly identified the dog-owner pairs. When the owners’ mouths were concealed, participants were correct 73 per cent of the time.

But when the eyes of either humans, or the dogs were blacked out, there was no accuracy at all, simply random guesses. When participants were shown only the eyes of the dog and the human, their accuracy rose to 74 per cent.

The conclusion reached was that people choose to get dogs that look similar to themselves – but mainly in the eye region.

The psychological mechanism, that explains why a person might choose a dog who looks similar to themselves, is”familiarity”, known in technical terms as the “ mere exposure effect”.

That is why we like the same authors, the same “oldie” songs. That is why we vote for actors, and the wives/children of well known people, without caring about their competence. It is also the reason why fake news has so much strength – repeated every few weeks, it takes on a life in our imagination simply because we are familiar with it. We are familiar with our own faces. So, anything that looks like us arouses a warm response. In a test done by Dr Stanley Coren, 104 women were asked to look at the heads of four dog breeds: an English Springer Spaniel, a Beagle, a Siberian Husky and a Basenji. The women rated them on looks, friendliness, loyalty and intelligence. The women were divided into those with longer hair styles that covered the ears and those with shorter or pulled back hair that exposed the ears.

The results? Women with longer ear covered hair preferred beagles and spaniels with longer ears that framed the face. Women with shorter hair and visible ears chose the Siberian Husky and the Basenji with pricked ears.

Now a new study done by social psychologists at Michigan State University says that dog and owner personalities also tend to be similar.

The study had 1681 owners of dogs evaluate their own personalities and the personalities of their dogs. Researchers found that most of them shared personality traits. An agreeable person was twice as likely to have a dog that is happy and less aggressive than one who was moodier. Loving responsible owners rated their dogs as amenable to training. Neurotic owners rated their dogs as fearful.

Obviously the study could not rely on just the observation of the owner, as it might be biased. But acquaintances rated the dog in the same way as the owner did.

This is the standard personality guidelines for personality comparison: Neuroticism or emotional stability – is a person oversensitive and nervous, or secure and confident.

Extraversion – is the person outgoing, sociable and energetic, or solitary and reserved.

Agreeableness -is a person friendly and compassionate, or cold and unkind. Conscientiousness – is the person hardworking, efficient and organised, or easy-going, lazy or careless.

Openness – Intelligence levels – is the person inventive and curious, or consistent and cautious When the owners rate the personality of their dogs, using a test developed by the University of Texas to measure a dog’s personality, the owners rated their dogs as similar to themselves in all five of the personality traits.

Family members rated the dog as well and the results showed, that in four out of the five personality characteristics, these family members saw the same traits in the dog as in the dog’s owner. However, both these studies apply to one dog households. If there is more than one, the similarities become less consistent.

A study by the University of Vienna, published in the journal PLOS, recruited 132 dogs and their owners, monitoring the stress of each member of the pair using both behavioural tests (how they reacted to perceived threats in the lab) and physical markers (heart rate and saliva samples to detect the stress hormone cortisol). The scientists found that the more anxious the owner, the more neurotic the dog. If the owner was relaxed, so was the dog.

A study by the University of Vienna, published in the journal PLOS, recruited 132 dogs and their owners, monitoring the stress of each member of the pair using both behavioural tests (how they reacted to perceived threats in the lab) and physical markers (heart rate and saliva samples to detect the stress hormone cortisol). The scientists found that the more anxious the owner, the more neurotic the dog. If the owner was relaxed, so was the dog.

Why do these similarities exist? Maybe, because the owners tend to pick dogs who are similar to themselves. But even more, through our daily interactions with them we shape their personality.

Of course, this is a complicated issue. Do friendly people choose friendly dogs? Or do friendly people take their dogs out more so that the dog becomes better socialised? Dr Stanley Coren, professor of psychology at the University of British Columbia, researched 6000 people’s personalities in 1996 to bring out a chart that predicted the breed of dog that they were likely to choose. The data from that study, which resulted in the book Why We Love the Dogs We Do, was not a comparison of the personality traits of the dog and its owner, but on how the personality of the human affected his attitude toward certain types of dogs.

For instance, the study found that individuals who owned aggressive breed dogs had life histories associated with aggression.

When Lambu came to me he had been thrown out of three homes for bad behaviour. Alpha male, he needed attention and would not tolerate any other dogs. For the first few months he drove away all the other 24 that live with me, and took the entire front of the house for himself.

As time went on, he has become far less aggressive, gets on with the dogs and is a mature well balanced personality whom one can talk to. All my dogs are throwaways, or crippled in some fashion. When they settle down, none of them are competitive, all of them are curious and they tolerate people while wandering through the world with their own personal agendas. We share many traits.

They came in having suffered through contact with the world. In my no demand house they relax, as do the insects, birds, monkeys and the occasional snake. Dog personalities aren’t set in stone. They change as they grow and are influenced by their lifestyles and experiences. The dog you take home from the shelter isn’t the same dog you’ll have a year from now. You have the power to change it. Nurture is more important than nature.