Did you know that coffee drinking is very bad for women, but not for men?

Well, actually, that’s not true at all. This lie was, however, the subject of a clever experiment by the late social psychologist Ziva Kunda. She created a fictitious article claiming that caffeine was harmful to women’s health, and then handed it to two groups: people who drank a lot of caffeine and people who barely touched it. Everyone was asked how persuasive they found the research.

Most readers thought the evidence was somewhat convincing, but one group was sceptical. Can you guess who? Yes, women who were heavy caffeine drinkers.
Of course, this tendency isn’t limited to caffeine. 

-Kunda also wrote about a personal example: she told her mother, a heavy smoker, about an article warning that smoking during pregnancy could be harmful. Her mother casually dismissed the article, pointing instead to her own tall sons as evidence that the warning didn’t apply.

Like the caffeine study, it shows how we are prone to cherry-picking or reinterpreting information to protect habits or beliefs that matter to us personally.
It’s a simple illustration of a simple truth: when information threatens something we value, our instinct is to push back.

This is known as motivated reasoning. It’s the tendency to interpret information in a way that protects our existing beliefs or self-image. Instead of simply asking, ‘Is this true?’, our minds tend to ask, almost automatically, ‘Do I want this to be true?’ We then embrace information that supports what we want and question information that doesn’t. So do we believe what we want to believe?

In a word, no. It’s more complicated than that. Cognitive psychologist Professor Thomas Gilovich has an elegant way of putting it. When we want to believe something, we ask: ‘Can I believe it?’ 

The bar is low. We don’t need a mountain of evidence.

When we don’t want to believe something, we ask: ‘Must I believe it?’ We don’t dismiss the information, but we do look for a higher standard of evidence, and we’re quick to latch on to anything that lets us delay accepting the conclusion.

Various studies capture this ‘Can I?/Must I?’ distinction. In one, participants took a sham medical test for an enzyme deficiency. The paper in the saliva was guaranteed to stay the same colour, but participants were told different things about what that colour meant. Those who thought it signalled good news accepted the result immediately. Basically, it was a case of ‘Can I believe it? Yes, I can’. Case closed.

However, those who thought it meant bad news repeated the test, shook the paper, and dipped it again and again. ‘Must I believe it?’ Could the test be wrong? Could there be some other explanation? Case not closed.
‘Can I believe it?’ versus ‘Must I believe it?’ in real time.

Antidote

To repeat, motivated reasoning is not the same as lying to ourselves. It’s much more subtle than that. Small emotional nudges, such as pride, fear, irritation, and shame,  can tilt how we interpret things without us even being fully aware of it.
The writer Tim Harford offers a helpful antidote, suggesting we simply notice our feelings as part of the reasoning process.
‘Rather than requiring superhuman control of our emotions, we need simply to develop good habits’, writes Harford. 

‘Ask yourself: how does this information make me feel? Do I feel vindicated or smug? Anxious, angry or afraid? Am I in denial, scrambling to find a reason to dismiss the claim?’

This is good advice. Our emotions are not the enemy but if they go unchecked, they can cloud our judgment. By pausing long enough to register our reactions, we create a little bit of space, enough to examine the evidence rather than our instinctive discomfort with it.

That moment of noticing is not just a cognitive skill, but a basic tool for managing our emotional wellbeing.