The right heat to be upbeat

New research into how climate affects personality suggests you’ve hit the social sweet spot if you are growing up in a place with an average temperature of 22 degrees Celsius.

Scientists from Melbourne University and Peking University said this ‘‘pleasantly warm’’ temperature played a key part in growing individuals’ personality.

They said people who grew up in such a climate were more emotionally stable, extroverted and open to new experiences.

The research was a joint project that used two large-scale studies in the United States and China to test if cultural differences changed the impact of climate.

It didn’t. The results on the impact of temperature were the same in both countries.

In both it was found that people in these areas with a temperature closer to 22 degrees Celsius scored higher on personality factors related to socialisation, stability (agreeableness, conscientiousness, emotional stability) and personal growth and plasticity (extraversion and openness to experience) than people who lived in hotter or colder places.

The researchers said the starting point was knowing that human personality traits differ across geographical regions.

What they were trying to find out was what part of geography contributed to personality differences.

Temperature was thought to be a crucial factor.

Humans constantly experience and react to the temperature, so they felt it must significantly affect habitual behavioural patterns and therefore personality.

The researchers called 22 degrees Celsius ‘‘the psychophysiological comfort optimum’’ and said that climate encouraged people to explore, enjoy new experiences and have lots of social interactions.

But when the temperature was too cold or too hot, then people stayed closer to home.

They also tested whether other climate factors like humidity or wind speed affected personality, but only temperature appeared to be a key element in all seven of the factors.

The researchers said the study was observational, so could not show cause and effect.

‘‘While much is known about the effects of temperature on human health and performance ... our findings offer insights into why people in different regions of the world exhibit different personality traits and behaviours.

‘‘As climate change continues across the world, we may also observe concomitant changes in human personality.

‘‘Of course, questions about the size and extent of these changes await future investigation,’’ the researchers said.

The study was reported at Nature Human Behaviour.