Researchers at the University College London have found that participants in a study consistently rated the skin of another person as being softer than their own, whether or not it really was. The researchers suggest that this phenomenon may exist to ensure that humans are motivated to build social bonds through touch.

“What is intriguing about the illusion is its specificity,” said Antje Gentsch of the University College London. “We found the illusion to be strongest when the stroking was applied intentionally and according to the optimal properties of the specialised system in the skin for receiving affective touch.”

This system typically responds to slow, gentle stroking found in intimate relationships and encodes the pleasure of touch, Gentsch explained.

“The illusion reveals a largely automatic and unconscious mechanism by which ‘giving pleasure is receiving pleasure’ in the touch domain,” said lead researcher Aikaterini Fotopoulou.

Many studies have focused on the benefits of touch for the person receiving it. Yet, Fotopoulou and her colleagues said, remarkably little is known about the psychological benefits of actively touching others.

Earlier studies showed that softness and smoothness stimulate parts of the brain associated with emotion and reward. Therefore, this “illusion” that other people are softer ensures that reaching out and touching another person comes as its own reward. This rewarding illusion acts as a kind of “social glue,” bonding people to each other.