Want to shut someone up? Try blinking slowly

HUMANS use blinking as a subtle way to control conversations, a study has found.

Rapid blinks can encourage others to speak more, while slower ones can discourage speaking. Scientists say they should be considered as conversational cues, a bit like nodding the head.

Blinks have a clear physiological function, keeping the eyes moist and clear, but we do around 13,500 of them a day, many more than is needed for this purpose alone. We also blink more frequently in conversation than when silent.

Scientists at the Max Planck Institute for Psycholinguistics in Nijmegen in the Netherlands set out to test what other purpose blinking serves, according to the PLOS One journal. They created a computer face – an avatar – that acted as a virtual listener and asked volunteers questions such as ‘How was your weekend?’. They controlled the avatar’s blinking, with short blinks lasting 208milliseconds and long blinks 607milliseconds. A millisecond is a thousandth of a second.

They found that the difference between the blinks was picked up by the listener. Long blinks resulted in substantially shorter answers, while shorter blinks led to replies that lasted several seconds longer.

The researchers said: ‘One of the subtlest of human movements – eye blinking – appears to have a surprising effect on the co- ordination of everyday human interaction.’