The Psychologist guide to… Weather

Heat raises the honks…

It may be common knowledge that there is an increase in violent crime as heat rises, but the relationship between temperature and violence isn't linear. 'It's curvilinear,' explains psychologist, Professor Trevor Harley, 'and it broadly follows the shape of an inverted U. Following a study of the number of aggravated assaults in Dallas, USA, a southern city with plenty of hot days to provide data, we can see the number of assaults rises as the temperature rises to approximately 30˚C, but, as it goes above that, the amount of violence goes down again.' 

We don't just observe an increase in violent crime as the mercury rises, explains Harley; 'the incidence of less drastic aggression, such as road rage, increases too. In one study carried out in Phoenix, Arizona, a researcher sat at the same road junction every Saturday from April to August, during which period the temperature ranged from 29°C to 42°. When the lights turned green, she just sat there. The researchers measured the frequency and duration of honks from the cars behind her, and honks became more frequent and lasted longer the hotter the weather.'

Hot weather increases crime and punishment

A new study by Patrick Behrer and Valentin Bolotnyy has looked at how the weather impacts the punishment of crime. 'Heat reduces self-control, negatively impacts mood, increases aggression, and places heightened stress on cognitive faculties,' explain Behrer and Bolotnyy, 'and, consequently, not only does crime increase but police make arrests they likely should not be making. Judges too, working on tight schedules make harsher and more punitive judgements.' Their study found that courts appeared to issue more severe punishments on hotter days with the length of confinement increasing by approximately 6.5%. This study, argue the researchers, highlights a concern that climate change could have a significant impact on the criminal justice system.

Your university choices may be cloud-dependent

Research by Uri Simonsohn suggests that weather can play a sneaky part in college admissions. One study looked at 682 university applicants and how the weather affected the way interviewers perceived them: on cloudy days they preferred applicants with strong academic profiles, while on sunny days non-academic attributes, such as being athletic or taking part in extra-curricular activities, were given more credit. In Simonsohn's words, 'clouds make nerds look good!' 

However, as Professor Harley explains, studies have shown that these decisions work both ways: 'on cloudy days applicants are more likely to prefer institutions with strong academic records at the cost of non-academic strengths. When Simonsohn examined the behaviour of 1,284 prospective students at a college known for its "academic strengths and recreational weaknesses", cloud cover increased the probability of enrolment, by almost 10%!'

Heat health depends on your wealth

Extreme heat is a threat to our health, and we become more vulnerable to this as we age and our body temperature regulation deteriorates. Studies have now found that exposure to extreme heat in older people could also trigger detrimental effects in the brain. However, a US study found that heat-related cognitive decline affected people from poorer neighbourhoods much more; perhaps, say researchers, as they are less likely to have air-conditioning, access to green spaces and quality healthcare. 

The risk isn't just from hot days either; a recent German study found that nocturnal heat exposure increased risk of strokes in the elderly. In recent decades, nighttime temperatures have increased faster than daytime temperatures. Researchers stress that these findings highlight the urgent need for preventive measures to mitigate the potential impact of nocturnal heat stress, particularly in the context of future warming at night.

The climate can determine our personality

Can the weather really affect a child's development? According to a study by Wei et al. (2017), it really can. 

The research team found that children growing up in southern California are more likely to be friendly, outgoing, and inquisitive than those growing up in chilly Minnesota. Professor Harley explains warmer weather means that children are more able to wander around outside, exploring, meeting people, and taking more risks than they would do if stuck indoors. Harley also explains that the season in which a person is born matters too and that people born in summer tend to be healthier and more outgoing, with temperature, again, apparently being the most important variable. However, he also adds that behaviour is more complex than simply, 'good weather leads to good mood, and bad weather bad mood.' He points to a study by Jaap Denissen and colleagues (2008), who found that the amount of sunshine, temperature, and humidity affected mood and energy levels only to a certain extent, however, they also found that rising temperatures make people less anxious and sceptical.

Seasons have more impact than we realise

Seasonal affective disorder (SAD) has long been recognised as a problem for many people as the days become shorter. However, this isn't the only example of seasonal impact on our psychological functioning. A team at the University of British Columbia documented how seasonal changes impact numerous aspects of psychological functioning; from the colours we prefer to our sexual behaviour. Some far-reaching examples include warmer temperatures having an impact on our feelings of fullness after eating and waiting staff receiving the biggest tips during the Christmas season. 'So many potential influences are at work here', say the researchers, 'not just changes in temperature and light but cultural events and national holidays also have a role to play'. Whatever the precise nature of the seasonal trigger, 'seasons appear to be a fundamental source of variability in how people think, feel and behave,' they conclude. 

Rain may help us to remember

We know that we're more likely to remember events that are consistent with our current state of mind. However, a study by Joseph Forgas and colleagues looked at how weather can affect our memory via its effects on our mood. 

The researchers employed the help of a shop in Sydney and tested the ability of 73 shoppers to recall ten objects that were placed around the counter. The shoppers were quizzed after they left the store, with half of them tested on rainy, cloudy days and the others tested on bright, sunny days. They all spent the same amount of time in-store. A mood questionnaire confirmed that the shoppers tested on rainy days were in a worse mood than those tested on a sunny day. And the memory test showed the rainy-day shoppers correctly identified three times as many items as the participants tested on a sunny day. Moreover, the rainy-day shoppers were less likely to have false memories for objects that hadn't been around the counter. So, next time you're suffering from brain-fog, perhaps you can blame the sunshine!

We only see the sunny side of heatwaves

Media reports surrounding heatwaves are becoming more and more common place as Earth warms up, however, a recent study found a startling difference between images used in coverage and the textual content. A team led by Saffron O'Neill at the University of Exeter looked at media coverage of extreme weather in four countries impacted by the 2019 European heatwaves; France, Germany, the Netherlands, and the UK. Their findings highlighted why we may often think of extreme heat as a reason for celebration at a first glance of the news. Although less than 1% of the actual words of the news feature about extreme heat had a positive tone, the images they used to illustrate their features tended to depict people who were "expressing happiness" through smiles, laughs, hugs, play, and even with pictures of some individuals jumping for joy. The images were also full of light, featuring blue skies and water and colourful leisure items. One particular feature in the Daily Mail showed a young woman in a fountain wearing a t-shirt saying "hotter than wasabi"; the text however, detailed the deaths of three people due to extreme weather.

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