London, Sep 11 (IANS): If you find that whenever you touch your partner's skin and it feels much softer that yours, then you are probably living in an illusion -- apart from a little pleasure, of course.

In other words, this “social softness illusion” in the mind of the touch-giver is selective to the body parts and the stroking speeds that are most likely to elicit pleasure in the receiver.

In a series of studies by researchers from University College London, participants consistently rated the skin of another person as being softer than their own whether or not it really was softer.

The researchers suggest that this phenomenon may exist to ensure that humans are motivated to build social bonds through touch.

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

What is intriguing about the illusion is its specificity.

“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,” explained co-author Antje Gentsch.

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

Social touch plays a powerful role in human life, from infancy to old age, with beneficial effects on physical and mental health.

Many studies have focused on the benefits of touch for the person receiving it.

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.

For example, touching a baby in a gentle manner seems to give the mother tactile pleasure, the researchers say, over and above any other thoughts or feelings the mother may have in the moment.

The next step is to examine the neuro-physiological mechanisms involved in giving affective touch, the authors concluded in the Cell Press journal Current Biology.