Shaking hands for more than three seconds can trigger anxiety and affect relationships, study finds

US President Trump gripped Mr Macron’s right hand so firmly that their knuckles turned white.

Dr Emese Nagy, a reader in psychology who led the study, said the findings highlight the importance of introducing ourselves appropriately. She added: "Handshakes are a particularly important greeting and can have long-lasting consequences for the relationships that we form.

"There has been evidence to suggest that many behaviours, such as hugs, fall within a window of approximately three seconds and this study has confirmed that handshakes that occur in this time frame feel more natural to those who participate in the greeting.

"While shaking hands for longer may appear to be a warm gesture on the surface, we found that they negatively affected the behaviour of the recipient, even after the handshake was finished.

"Politicians are particularly keen on prolonged handshakes, which are often used an expression of warmth but also as a means of demonstrating authority.

"However, our findings suggest that while doing so might look impressive for the cameras, this behaviour could potentially jeopardise the quality of their working and personal relationships from the beginning, which could have repercussions for millions of people."

The team found participants showed less interactional enjoyment after the longer handshake, laughing less and showing increased anxiety.

Handshakes lasting less than three seconds resulted in less subsequent smiling, but did feel more natural to those who participated.

No behavioural changes were associated with the no-handshake control experiment.

The results can be found in the Perceptual And Motor Skills journal, Effects Of Handshake Duration On Other Nonverbal Behaviour.

Previously in 2011 Dr Nagy analysed hugs and what they say about shared experiences.