As leading canine psychology experts Evan MacLean and Brian Hare have put it, “When your dog is staring at you, she may not be just after your sandwich,” according to the Associated Press.

A new study conducted by Japanese veterinary science researcher Takefumi Kikusui is the first to explore the science behind the bond between man and his best canine friend. The research used 30 pairs of dogs and their owners to determine whether there is a chemical basis for the love shared between pets and humans.

The study focused on measuring levels of the oxytocin – the hormone typically connected to feelings of love and well-being – in both humans and dogs. Kikusui’s team took urine samples from the dogs and their owners before conducting their experiment to create a baseline for the hormone levels.

The dog-and-owner pairs were divided into three different groups for a period of 30 minutes: one group gazed into the eyes of their dogs, the second group petted their dogs, and the third talked to their pets. Urine samples were collected again after another 30 minutes.

After analyzing the samples, researchers found that both dogs and humans who gazed into each other’s eyes experienced a significant increase in oxytocin levels compared to the other groups. Touching the pet also increased oxytocin levels compared to owners who did not come into physical contact with their pets.

Long periods of eye contact have been known to benefit bonding experiences in cases of romantic relationships and mother-and-child relationships among humans, but this is the first study to apply it to bonds between different species, according to researcher Larry Young of Emory University.

However, Clive Wynne of Arizona State University has responded by saying that the findings of the study are inconclusive. Wynne is a psychologist who focuses on interactions between dogs and humans.