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Humans aren’t predisposed to optimism, study finds

Monty Python told us to ‘always look on the bright side of life’, but it seems optimism isn’t as ingrained in human nature as previously thought, a new study claims.  

Researchers have found that humans aren’t predisposed to optimism, nor do we go around with ‘a pair of rose-tinted glasses’ – a belief that may have biased the findings of previous studies. 

The experts cast doubt over past research supporting the existence of ‘irrational optimism bias’ – that humans innately have a feeling that everything will be alright.  

Glass half full or half empty? A ‘sizeable body of literature’ suggests people’s belief updating – beliefs to take into account a new piece of information – is optimistically biased, such that their beliefs are updated more in response to good news than bad news. The new research paper refutes this idea, however


An ‘irrational optimism bias’ describes when people look too much on the bright side of life.

They underestimate their chances of negative experiences while overestimating their chances of positive events.

Irrational optimism bias can contribute to financial crises, people’s failure to look after their health, or inaction over climate change, the researchers claim. 

This over-optimistic tendency is also taken into account by the UK government when planning large infrastructure projects, they say. 

Researchers now say there are flaws in research supporting the existence of irrational optimism bias.

The new study was carried out by researchers at the University of Bath, University College London, and Birkbeck, University of London.

The authors are not saying that irrational optimism bias doesn’t exist, but that an assumption that it’s an innate part of human nature may have affected the accuracy of previous optimism studies. 

They say prior scientific studies have generated ‘false positives’ – data patterns that look like people are being over-optimistic, where no such bias exists. 

‘Our experiments show that the method commonly used to evidence such optimism is flawed, giving rise to “optimistic” belief updating where optimism is not possible,’ said study author Jason Burton at Birkbeck. 

‘This is not to say that optimism bias cannot exist in the real world, but that new improved methods are needed. 

‘Essentially, current methods return false positives.’       

For their study, the researchers conducted several experiments using a methodology that has been widely accepted in past optimism research – known as ‘the update method’.

This method involves participants estimating their chance of experiencing a life event and then re-estimating it after being provided with the average person’s actual chance of experiencing the event – known as ‘belief updating’.

Typically, this has been done with negative life events, like contracting a disease or getting a divorce – in other words, various forms of bad news cases that would elicit a strong emotional response. 

Humans aren't predisposed to optimism, nor do we go around with 'a pair of rose-tinted glasses' (stock image)

Humans aren’t predisposed to optimism, nor do we go around with ‘a pair of rose-tinted glasses’ (stock image)


Thinking too positively can prevent you from reaching your goals, by making you become lazy or complacent, one expert has said. 

‘There is no doubt that a simplistic view of positive thinking…can be dangerous,’ Tim LeBon, a psychologist at City University London, told MailOnline. 

‘There is plenty of evidence that fantasising about a positive future can lead to complacency.

‘You also set yourself up for feeling shocked and distressed when the future doesn’t turn out so good.

‘An oversimplistic recommendation to avoid thinking positively and to think negatively instead would be even worse,’ Mr LeBon told MailOnline.

‘We need to understand the power of both positive and negative thinking.’

Positive thinking is important because it helps drive motivation, and keeps us working towards the goals we hope to achieve.

But thinking negatively helps us get ready for failures or setbacks, so when bad things happen we are prepared to deal with them.   

For example, a participant might be asked to estimate their chance of experiencing a negative life event, like getting divorced, to which they might reply 5 per cent. 

They’re then presented with the actual proportion of the general population that gets divorced in their lifetime – 45 per cent – before updating their belief. 

Here, the bad news of finding out the chances of divorce are higher than expected is a form of ‘undesirable information’. 

‘Trials on which participants receive desirable information typically elicit greater updates than trials with undesirable information, which is interpreted as evidence of optimism in belief updating,’ the researchers explain in their paper. 

For this new study, the researchers tested the same ‘update method’ but removed the emotional element.

They instead used neutral non-emotional examples, such as participants estimating the chances of the next passing car being the colour black, or of getting a haircut in the next four weeks.

Despite changing the examples and removing the emotional elements in the questions, the same optimistic pattern was observed.

This simply proved that it wasn’t the element of optimism that was changing their beliefs, leading the team to challenge the validity of the methods used in other research claiming to prove optimism bias. 

‘What we’re really saying is that, when emotional aspects are removed, there should technically be no optimistic patterns of changing beliefs,’ co-author Punit Shah, an associate professor at Bath’s department of psychology, told MailOnline.

‘By definition, the removal of emotion makes it impossible to get good or bad news about the chances of life events. 

‘That we still find beliefs are changing about neutral events indicates that this task is simply not measuring optimism and, instead, most likely a statistical artefact.’

Researchers argue that valence – whether information is good, bad, or neutral – is essential to the claims supporting the existence of optimistic ‘belief updating’.  

The team don’t deny evidence for optimism in certain situations, but ‘that is not to say that humans are generally optimistic’, said Shah. 

Eric Idle (left) and Graham Chapman sing 'always look on the bright side of life' in the final scenes of Monty Python's Life of Brian (1979). But humans aren't as predisposed to optimism as we may have been led to believe

Eric Idle (left) and Graham Chapman sing ‘always look on the bright side of life’ in the final scenes of Monty Python’s Life of Brian (1979). But humans aren’t as predisposed to optimism as we may have been led to believe

‘We are certainly not saying that optimism doesn’t exist, or that people are not overly optimistic in certain situations – e.g. sports fans for weak teams.

‘But our research questions the general existence of optimistic bias as a default mode of human operation, as many have argued exists for many decades.’

Irrational optimism bias can contribute to financial crises, people’s failure to look after their health, or inaction over climate change, the researchers claim. 

‘Researchers and policy makers have made careers based on the idea of optimism bias, but it is time to reconsider evidence for this psychological phenomenon,’ Shah said.

‘Optimism bias is continually being used to guide large government projects, seemingly to manage projections about the time and financial costs of project. 

‘Our latest research, building on our previous research, supports a re-examination of optimism bias before it guides policy any further.’       

The new study has been published in the journal Cognition. 


People who are pessimistic die earlier than those who don’t have overtly negative or positive views, results of a 2020 study suggested.

Researchers found that those with negative outlooks about the present or future died about two years earlier than the average person. 

But rather surprisingly, being particularly optimistic was not found to increase life expectancy. 

The team, from QIMR Berghofer Medical Research Institute in Brisbane, Australia, said pessimists likely do not look after themselves as well, resulting in their health declining sooner than the health of others.

Previous studies have found an association between optimism and pessimism and certain disease, or lack thereof. 

However, such research had grouped the two onto one scale rather than separate scales, resulting in people with low scores being classified as optimists.  

‘Optimism and pessimism are not direct opposites,’ lead author Dr John Whitfield, a clinical biochemist, at QIMR Berghofer, said.

‘The key feature of our results is that we used two separate scales to measure pessimism and optimism and their association with all causes of death.’ 

For the study, published in the journal Nature, the team looked at a questionnaire of around 3,000 participants aged 50 or older. 

The questionnaire was part of the Life Orientation Test, which looked at the health of Australians between 1993 and 1995 with follow-up information only available through the end of 2009.

Participants were given a score on an optimism-pessimism scale based on how  much they agreed or disagreed with optimistic and pessimistic statements.  

Such statement included: ‘I’m always optimistic about my future’ or ‘If something can go wrong for me, it will’. 

Those who scored higher as pessimists  [were likely to die two years earlier on average than those who did not rate as pessimistic.]

Pessimists were more likely to die earlier from cardiovascular disease and other causes of death, but not cancer.

What’s more, mood disorders such as depression did not appear to have an effect on the link between pessimism and mortality.  

It’s not clear why pessimists die sooner, but Whitfield does not believe the disease causes the pessimism or vice versa.

‘People who are pessimistic might be thought to not look after themselves and their health as well – they might think there’s no point in following advice about diet and exercise and so on,’ he told ABC Australia.

‘There are indications that optimistic and pessimistic attitudes can have effects on brain and blood biochemistry, inflammation perhaps on the arterial wall.’

Researchers also found that high optimism scores did not correlate with shorter life expectancy or a longer one.

There was also no statistical significance in optimism or pessimism scores between men and women.