Participants stood on force platforms while undertaking a range of tests; with no physical contact, a shoulder grasp and a light touch.

The researchers looked at pairs of volunteers in a range of tests to understand how visual and mechanical interactions between them would affect their stability.

"There's something very human, very instinctive, that makes us reach out and grab something or someone when we're unsure of our balance and experience sway. We know this. But being able to significantly reduce that sway with even the gentlest touch tells us a lot about how our body relates to the people around us," said Raymond Reynolds from the University of Birmingham in Britain."

When Person A has his eyes open, and Person B has his eyes closed, and they apply the slightest fingertip contact we see Person B experience a reduction in sway."

"Surprisingly, Person A also experiences a reduction in sway - it is quite literally a case of the blind leading the sighted," Reynolds added.

The volunteers experienced a 37 percent reduction in sway when grasping each others' shoulders.

Even a non-forceful touch with the fingertip accounted for an 18 percent reduction in sway, and it is the underlying mechanisms behind this that the team have described for the first time.

The phenomenon in question describes how each person essentially estimates how 'upright' they are, based on a weighted combination of sensory feedback from themselves (the inner ear, the sense of force underfoot and vision) and feedback based upon the motion of their partner, Reynolds concluded.

The study appeared in the journal Interface.