Being warm-hearted is easier if you’ve got warm hands, says a new study.

Psychologists found people asked to hold hot objects in their hands were more likely to cooperate with other people than those holding something cold.

Experts say it could be the reason why giving customers hot drinks in supermarkets and other stores works to the benefit of retailers.

The tactic makes people more likely to buy because they feel warm towards the seller, whereas a cold drink would not have the same effect, it is claimed.

It is thought an evolutionary trick of the brain is responsible due to the same brain area used for processing interpersonal warmth - friendliness to others - also dealing with physical warmth, with one influencing the other.

So when we say we have “warmed to someone” it’s literally true, say researchers Professor Lance Workman and Simon Storey.

A study involving 30 pairs of volunteers was carried out using a game which measure people’s willingness to cooperate.

Before performing the task, 15 pairs of volunteers were asked to do it while holding gel hand-warmers heated to a pleasant temperature and the remainder were asked to do it while holding them at a much cooler temperature, and again vice versa.

In the game, known as the Prisoner’s Dilemma, each pair were asked to produce a card showing they would either cooperate or act in self interest.

People cooperated significantly more frequently and gained more sweets when they were holding a warm object, according to results to be presented today at the British Psychological Society’s conference in Birmingham.

Prof Workman said “There is evidence that during our evolution the part of the brain responsible for processing interpersonal warmth came to ‘piggyback’ on top of the part of the brain responsible for physical warmth.

“So when we day we have ‘warmed to someone’ this is, in a sense, literally true.

“We suspect that simply by giving someone a sensation of warmth they are more likely to cooperate under other circumstances” he added.

Prof Workman said it was a well known sales tactic for retailers to give customers a hot beverage.

“They know it makes a sale more likely - but didn’t know why. Probably the assumption was it worked because the drink was free but the reason may be more primeval” he said.

“The upshot is that if you’re making friends - give them a hot drink rather than a cold one” he added. - Daily Mail