We already know dogs can smell fear, but can they also detect lies? New research suggests that your dog may be more perceptive than you think. A study led by Akiko Takaoka of Kyoto University in Japan shows that dogs are able to judge human trustworthiness and adjust their behaviour based on past experiences.

The study was carefully designed to test how dogs react to inconsistent signals from humans. At first, researchers pointed to a container that had food hidden inside. The dogs eagerly ran to it. Then the researchers pointed to another container, this time empty. The dogs still ran towards it, only to be disappointed.

When the researchers pointed to a third container, which once again had food inside, the dogs refused to approach it. All 34 dogs used in the experiment hesitated or ignored the signal. Their behaviour suggested they had learned not to trust someone who had previously misled them.

This indicates that dogs are capable of making social judgements. They seem to understand when someone is unreliable and are quick to change their response. Either they can spot a liar, or they simply stop trusting after a single bad experience.

John Bradshaw of the University of Bristol, who was not part of the study, commented that dogs prefer consistency. He noted that when gestures become unpredictable, dogs can grow nervous or uncertain.

Researchers plan to carry out a similar test using wolves, which are closely related to dogs. The aim is to explore how domestication may have shaped the way dogs interact with humans.

A comparable study was conducted on preschool children by Kimberly Vanderbilt and her team at the University of California, San Diego. It found that three-year-olds trusted both honest and dishonest adults equally. By the age of five, however, children began to favour trustworthy individuals.

Interestingly, dogs seem to learn this distinction more quickly. While young children may need more experience to decide who to trust, dogs appear to form their conclusions after only one or two interactions.

Takaoka said she was surprised by how quickly dogs dismissed the unreliable humans. “Dogs have more sophisticated social intelligence than we thought,” she explained. “This likely developed through their long-standing relationship with humans.”

So, if you’re thinking about tricking your dog for a laugh, it might be worth remembering – they’re watching you closely, and they don’t forget easily.