Most owners trust their dog's instincts about strangers - and it appears they're right to do so.
Dogs have been known to bark at complete strangers when out with their owners - leaving them puzzled about their pet's sudden outburst.
While some owners simply brush off their behaviour and think nothing more of it, others are convinced their dog knows something they don't.
A study, headed by comparative psychologist James Anderson at Kyoto University, in Japan, has explored how dogs view strangers who interact with or dismiss their owners.
In the study, a group of dogs watched on as their owners struggled to open a container.
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Unable to open it up, their owners passed it to an actor who would help before repeating the experiment with an actor who would refuse to help.
Mr Anderson and his colleagues found the dogs formed an almost instant dislike to the actor who refused to help their owner in their time of need.
He wrote: "If somebody is behaving antisocially, they probably end up with some sort of emotional reaction to it. Chances are that if these animals can detect cooperative tendencies in human actors."
They concluded: "Dogs negatively evaluate people who refuse to help their owners and nonhuman species can engage in third-party based social evaluations."
It comes after researchers carried out a study into dogs' understanding of human behaviour.
Researchers Judith Benz-Schwarzburg, Susan Monso and Ludwig Huber, from the Vienna Medical University in Austria, have been studying how dogs perceive humans with links to cognition and ethics.
The team learnt how dogs pay attention to a person's tone of voice and body language to determine if they're a 'good or bad person'.
They said: "Dogs have indeed special skills to understand and interact with humans due to the evolutionary history and domestication of the species and due to complex competences acquired by individual and social learning.
"We see accumulating evidence of their understanding of human emotions, gestures, and actions and of how much they are thus part of human culture and our social game. Bonds between dogs and humans are selective, intense, and vary in quality.
"Affiliation plays a motivational role in dog behaviour and shapes the dogs’ attitudes as well as their interaction with humans.
"All of this, however, has to be seen in the light of a comprehensive characterization of the human-dog relationship, which is a socially constructed practice with clear power relations.
"We have argued that the human-dog relationship is a dominance relationship where humans are usually in command of power.
"If caregivers are unaware about how much their dogs pay attention to subtle communicative cues and how much they understand about as well as attend to their caregivers’ emotions, gestures, and actions, a range of conflicts can arise.
"Instead we should invest into building relationships of trust with dogs that live up to ideas of companionship."
Do you have a dog story to share? Email paige.freshwater@reachplc.com.
