A steaming hot drink may be all it takes to see the world through rose-tinted glasses, psychologists have found.

Holding a warm cup of coffee was enough to make people think strangers were more welcoming and trustworthy, while a cold drink had the opposite effect, a study found.

The warmth of a drink also influenced whether people were more likely to be selfish or give to others, researchers report in the journal Science. A team led by John Bargh at the University of Colorado set about testing whether hot and iced drinks influenced perceptions of others after noting how frequently "warm" and "cold" are used to describe personalities.

In one test, 41 volunteers were asked to hold a cup of coffee while they took an escalator to a fourth-floor lab. Once there, they were asked to read about a fictional character and give their impression of them. The test was then repeated using an iced coffee drink.

The psychologists found the volunteers perceived the fictional strangers as significantly warmer characters after holding the hot drink. When ranked on a scale from one to seven, with one being cold and seven being warm, they rated people on average 11% warmer after holding the hot drink.

Scientists also checked whether temperature influenced people's own behaviour as well as their perception of others. They asked volunteers to pick up either a frozen or heated therapeutic pad used for sports injuries. After handling the pad for a few minutes, they were offered a drink for themselves, or a voucher to give to a friend. Those who handled the hot pads chose more often to give the voucher.