Category: Intelligence

5 Reasons It’s So Hard To Think Like A Scientist

Maria Goeppert MayerBy Christian Jarrett

Thinking like a scientist is really hard, even for scientists. It requires putting aside your own prior beliefs, evaluating the quality and meaning of the evidence before you, and weighing it in the context of earlier findings. But parking your own agenda and staying objective is not the human way.

Consider that even though scientific evidence overwhelming supports the theory of evolution, a third of Americans think the theory is “absolutely false”. Similarly, the overwhelming scientific consensus is that human activity has contributed to climate change, yet around a third of Americans doubt it.

We Brits are just as blinkered. In a recent survey, over 96 per cent of teachers here said they believed pupils learn better when taught via their preferred learning style, even though scientific support for the concept is virtually non-existent. Why is it so hard to think like a scientist? In a new chapter in the Psychology of Learning and Motivation book series, Priti Shah at the University of Michigan and her colleagues have taken a detailed look at the reasons, and here we pull out five key insights:

Continue reading “5 Reasons It’s So Hard To Think Like A Scientist”

Academically successful children smoke more cannabis as teenagers: is it time to rethink drug education programmes?

You want a joint?By guest blogger Simon Oxenham

Academically successful children are more likely to drink alcohol and smoke cannabis in their teenage years than their less academic peers. That’s according to a study of over 6000 young people in England published recently in BMJ Open by researchers at UCL. While the results may sound surprising, they shouldn’t be. The finding is in fact consistent with earlier research that showed a relationship between higher childhood IQ and the use in adolescence of a wide range of illegal drugs.

Continue reading “Academically successful children smoke more cannabis as teenagers: is it time to rethink drug education programmes?”

Smarter people are happier, says new analysis involving 80,000 participants, but only a bit

albert_einstein_headBy Christian Jarrett

“happiness in intelligent people is the rarest thing I know” Ernest Hemingway

A lot of us would like to be smarter and happier, but does one lead to the other? Folk wisdom suggests not: old sayings tell us that “ignorance is bliss” and that “only a fool can be happy”. What does the psychology literature say? A new meta-analysis in the Journal of Vocational Behaviour has combined the results from dozens of previous studies involving many tens of thousands of participants and, contrary to the received wisdom, it concludes that higher intelligence actually does correlate with greater happiness (or “life satisfaction”) and job satisfaction, but only weakly.

Continue reading “Smarter people are happier, says new analysis involving 80,000 participants, but only a bit”

If you like sick jokes, maybe it’s because you’re just so smart

By Christian Jarrett

Understanding jokes requires a certain amount of mental agility, psychologists tell us, because you need to recognise a sudden shift in meaning, or appreciate the blending of odd contexts that don’t normally go together. A new study in the journal Cognitive Processing has tested whether intelligence plays the same role in the appreciation of sick or black humour: the kind of jokes that make light of death, illness and the vulnerable. Consistent with past research linking intelligence with joke appreciation, the participants who most liked cartoons based on black humour also scored highest on verbal and non-verbal IQ.

Continue reading “If you like sick jokes, maybe it’s because you’re just so smart”

It’s now possible, in theory, to predict life success from a genetic test at birth

one week old newborn girl on daddy's hand.By guest blogger Stuart Ritchie

For decades, we’ve known from twin studies that psychological traits like intelligence and personality are influenced by genes. That’s why identical twins (who share all their genes) are not just more physically similar to each other than non-identical twins (who share half their genes), but also more similar in terms of their psychological traits. But what twin studies can’t tell us is which particular genes are involved. Frustratingly, this has always left an ‘in’ for the incorrigible critics of twin studies: they’ve been able to say “you’re telling me these traits are genetic, but you can’t tell me any of the specific genes!” But not any more. Continue reading “It’s now possible, in theory, to predict life success from a genetic test at birth”

Wisdom is more of a state than a trait


By Christian Jarrett

We all know the kind of person who did really well at school and uni but can’t seem to help themselves from forever making bad mistakes in real life. And then there are those characters who might not be surgeons or rocket scientists but have this uncanny ability to deal calmly and sagely with all the slings and arrows of life. We might say that the first kind of person, while intelligent, lacks wisdom; the second kind of character, by contrast, has wisdom in abundance. The assumption in both cases is that wisdom is a stable trait – how much someone has is an essential part of their psychological profile and remains constant through their life.

But a new study says this way of viewing wisdom is mistaken. The research in Social Psychological and Personality Science used a diary approach to gauge people’s wisdom in response to everyday problems, and the results showed that there is more variation in one person’s wisdom from one situation to the next, than there is variation in the average wisdom between people. Wisdom, it seems, is more of a state than a trait. Continue reading “Wisdom is more of a state than a trait”

Why do women do so much better at university than their school test scores predict?

Picture an American high school staff-room, late in the academic year, where a teacher called Alice is listening to her colleagues ride their favourite hobby horse: picking out which students have the most promise.

Eventually Alice leans forward and taps her laptop. “Less talk, guys, more data. If you want to know how a student will do when they get to college, look at their aptitude test scores.” Betty throws her a look. “That won’t work,” she says, ”girls go on to do better than their test scores predict. Those tests are faulty.” Charles, the faculty provocateur, snorts. “Faulty? Not at all. Girls are only getting better grades because they pick softer subjects with easier marking.”

As her older colleagues tear into each other, Alice reflects on a third possibility: that succeeding at university depends on much more than the cognitive abilities measured by the SATs and ACTs (standard tests taken at American high schools), and that women might be better prepared in these other departments. But to resolve this staff-room squabble, who can tell these explanations apart?

Psychologists from the University of Minnesota-Twin Cities, that’s who. In a new paper in the Journal of Applied Psychology, Heidi Keiser’s team examine Alice and Charles’ rival explanations for why high school aptitude tests under-predict girls’ later success at university.

The new research first compared the university grades of 2000 students from a single institution with their high school aptitude scores. Women scored better on their course than you would expect based on an earlier aptitude test, but once the researchers took account of the female students’ higher average trait conscientiousness, 20 per cent of their grade surplus disappeared – a finding that replicates earlier research.

The researchers then decomposed the students’ degree course into elements, reasoning that if conscientiousness has a role in the gender gap, this should be greatest when grades depended highly on discretionary effort, like participating in discussion or research, and least when grades depended on raw smarts. The data showed that high school aptitude scores underestimated female performance on these effort-sensitive course elements, but were no worse at estimating their success on quizzes and tests than they were for men. Overall, this supports Alice’s perspective – that women do better than expected at university because of their greater effort and conscientiousness.

In a second study, the researchers tested Charles’ counter argument that women perform surprisingly well because they pick easier courses. The data, from huge historical datasets comprising nearly 400,000 students, showed that the courses men tended to take were significantly meaner (that is, male and female students on these courses tended to achieve worse grades than expected given their academic history) and were also more likely to be populated with high-achieving students competing for grades. And these factors, primarily course meanness, did explain a little of the overall tendency for female over-performance… but not more than nine per cent, much less than the effect of conscientiousness. A weak score, then, to Charles.

What about our other teacher Betty? Right from the start, she said the aptitude tests, measuring cognitive ability, simply weren’t doing it right. She could still have a case: the hidden variables found in this study – conscientiousness and course selection – together accounted for less than thirty per cent of the gender gap – possibly much less, if the two effects are not independent from each other.

However, it’s also plausible that aptitude tests are doing a reasonable job, it’s just that there are many non-cognitive factors critical to university success, and that conscientiousness is just one slice of this pie (an exploratory look at other personality variables by Keiser’s team suggests as much). If so, it’s not that school tests and exams need to be improved, but that they give us just one part of what higher education requires. We must not lose sight of the wider attributes, found particularly in female students, that travel from classrooms and school projects into our seminar rooms and lecture halls, and beyond.


Keiser, H., Sackett, P., Kuncel, N., & Brothen, T. (2016). Why women perform better in college than admission scores would predict: Exploring the roles of conscientiousness and course-taking patterns. Journal of Applied Psychology, 101 (4), 569-581 DOI: 10.1037/apl0000069

Post written by Alex Fradera (@alexfradera) for the BPS Research Digest.

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Does being in a bad mood affect your mental performance?

We’ve all had days when we got out of the wrong side of the bed and the world looked greyer than usual. This daily variation in mood is a potential problem for psychologists who want to use tests to compare people’s mental ability – competing job candidates, for example. Mood, like tiredness and motivation, could be another factor that leads some people to perform below par, by their own standards, thus distorting the test results.

Indeed, there’s some evidence that being in a bad mood is distracting because it takes mental effort to deal with unpleasant emotions. Being in a good mood, by contrast, is thought to be energising. However, a new study in the journal Intelligence looked at how people’s mood and mental performance varied over five consecutive days and it actually found no link between the two.

Sophie von Stumm recruited 98 participants, mostly students (74 women; average age 24), to complete five different versions of the same three mental tests on five consecutive days, Monday to Friday. Seventy-seven participants turned up for all the sessions. One test concerned short-term memory (remembering lists of numbers or letters); another was a test of processing speed (comparing as quickly as possible whether strings of letters and numbers were identical); and the final test tapped working memory (involving mental arithmetic).

Each day, before beginning the mental tests, the participants completed a comprehensive measure of their current mood, using a sliding scale to indicate how much they were feeling 10 different positive emotions and 10 different negative emotions. Participants could arrive any time each day between 9 to 6 to complete the tests.

Von Stumm says she found “considerable” variability in the participants’ mental performance and their mood from one day to the next, with mood varying more than cognitive performance. But crucially, there was no coupling between the two. That is, daily changes in how well participants performed on the mental tests was not tied to daily fluctuations in their mood.

This result shouldn’t be taken to mean that serious emotional distress is not harmful to mental performance, but the results do suggest that mundane fluctuations in our mood are unlikely to affect our mental performance. So if you’re in a grump today, take heart – at least it’s unlikely to slow you down mentally.

Taking a more sceptical view, note the relatively small sample size and the fact the study only looked at fluctuations over five days. It’s possible the findings might differ over narrower (multiple tests in one day) or longer timescales.

Incidentally, there was a significant link between participants’ average positive mood across the study and their test performance – that is, participants who were generally in a better mood across the five days tended to perform better than less happy participants on the mental tests. “Put bluntly,” von Stumm said, “this suggests that people who have a general tendency to be more enthusiastic and alert have faster brains, but additional research will be needed to substantiate this observation.”


von Stumm, S. (2016). Is day-to-day variability in cognitive function coupled with day-to-day variability in affect? Intelligence, 55, 1-6 DOI: 10.1016/j.intell.2015.12.006

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

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What kinds of actions do people think of as most stupid?

To avoid people thinking you’re stupid, above all you need to refrain from undertaking risky tasks for which you lack suitable knowledge or skills. That’s according to new research published in the journal Intelligence, which is the first to systematically investigate the kinds of behaviours that people consider to be stupid or foolish.

Balazs Aczel and his colleagues collected online news stories that contained descriptions of stupid behaviour, for example from the New York Times, the BBC and the gossip site TMZ. They also asked 26 university students to keep a diary for five days of incidents they experienced that involved people acting stupidly. In the end, the researchers ended up with 180 stories, a small number of which they deliberately manipulated to alter the consequences of the stupid actions and the responsibility level of the perpetrator.

The stories were condensed down to brief (roughly two-sentence long) descriptions of the events, and shown to 154 undergrads in Hungary. The students rated the intensity of the stupidity on display and also rated how much 30 potential psychological factors (including things like overconfidence and fatigue) were to blame for the stupidity.

After analysing the students’ scores and explanations for the stories, the researchers deduced that there are three main categories of what people consider to be stupidity:

  • “Confident ignorance” which is when people engage in risky actions for which they lack the prerequisite skills or knowledge. Such actions received the highest ratings of stupidity and were encapsulated by a story of burglars who thought they were stealing mobile phones, but actually stole GPS tracking devices which allowed the police to find them. 
  • “Lack of control”, resulting from obsessive, or addictive behaviour. For example, a person who cancelled a meet up with a good friend because they couldn’t pull themselves away from a video game. This category was intermediary in the hierarchy of stupidity. 
  • “Absentmindedness – Lack of practicality” which refers to instances when people fail a practical task, either out of distraction or because of a lack of practical skills. This category was encapsulated by someone inflating car tires too far. In terms of stupidity ratings, the participants were most lenient toward these kind of acts.
Unsurprisingly, in each case, the participants rated acts as more stupid when the consequences were more serious, and when the perpetrator was in a position of more responsibility. This last point “suggests an explanation as to why experts and people in leadership positions receive more fervent scorn,” the researchers said. 
Aczel and his team speculate that people are generally rather preoccupied by acts of stupidity, either committed by themselves or others, because to maintain this vigilance is beneficial. By striving to avoid the label of stupidity, we are all galvanised toward avoiding actions, such as overconfidence, or mindlessness, that are likely to lead to misfortune or loss of status. 
This research has some obvious limitations – most glaringly that it relies on the judgments of a group of students in Hungary. It remains to be seen whether the results will generalise. Nonetheless, with so much published research and debate on what counts as intelligent behaviour, this study offers a refreshing change of direction. As the researchers put it, “the study of intelligent behaviour may benefit from understanding its flipside, unintelligent behaviour, which in turn may be inherently linked to our conception of stupid actions.”


Aczel, B., Palfi, B., & Kekecs, Z. (2015). What is stupid? Intelligence, 53, 51-58 DOI: 10.1016/j.intell.2015.08.010

further reading
How many ‘Doh!’ moments does the average person have?
Higher intelligence associated with “thinking like an economist”
Students say men are more attractive when they take risks, but only risks relevant to our hunter-gatherer ancestors

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

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Why do more intelligent people live longer?

227a6-senior2bchessBy guest blogger Stuart Ritchie

It’s always gratifying, as a psychologist, to feel like you’re studying something important. So you can imagine the excitement when it was discovered that intelligence predicts life expectancy. This finding is now supported by a large literature including systematic reviews, the most recent of which estimated that a difference of one standard deviation in childhood or youth intelligence (that’s 15 IQ points on a standardised scale) is linked to a 24 per cent lower mortality risk in the subsequent decades of life. That’s a pretty impressive link, but it immediately raises a critical question: why do brighter people live longer?

A new study (pdf) published in the International Journal of Epidemiology attempts to provide new, biological evidence to answer this question. But first, let’s think through the possibilities. We know that people with higher IQ scores tend to be healthier, possibly because they eat better, exercise more, are better able to understand health advice, are less likely to be injured in accidents and deliberate violence, and also because they tend to have better jobs. Here, the causal arrow is pointing from IQ to longevity – the effects of being smarter cause you to die later. But there are other explanations: what if having a lower IQ is just an indicator of an underlying health condition that’s the real cause of earlier death? Or what if the genes for having a healthier body are also the genes for having a healthier brain, and the causal pathway is from this third variable (i.e. genetics) to both IQ and longevity?

The authors of the new study, Rosalind Arden and colleagues, tested this last hypothesis, known as “genetic pleiotropy” (the idea that the same genes influence multiple different traits). They took three twin datasets, selecting in total 1,312 twin pairs where one or both of the twins had died. Then they correlated the twins’ IQ scores with the lengths of their lives (or their life expectancies, for those still living).

As they expected, the researchers found an overall lifespan-IQ correlation, albeit a small one (r = 0.12, where 1.00 would be a perfect match). Importantly, by comparing the correlations in identical twins (who share all their genes) versus fraternal twins (who share approximately half), they were also able to estimate the “genetic correlation” – the overlap in the two traits that’s caused by genetic differences. They found that, overall, 95 per cent of the correlation in IQ and longevity was due to genetics.

So, is this a final answer to the debate over the IQ-mortality connection? Does this show that, perhaps depressingly, the link isn’t due to changeable lifestyle factors, but actually some kind of genetic “system integrity” that underlies brightness and longer lives?

Ritchie’s critically acclaimed
new book is out now.

Not so fast. The important part is in the phrase “due to genetics”. In a 2013 Nature Reviews Genetics article, geneticist Nadia Solovieff and colleagues outlined all the potential causal mechanisms that might make two traits genetically correlated. They drew a critical distinction between “biological” and “mediated” pleiotropy. The former is the “obvious” inference, which is that the same genes cause both intelligence and longevity. But the latter possibility is that the variables only appear to be genetically correlated, because genes cause one factor, which then goes on to cause the other. That is, if genes cause intelligence, and intelligence (via lifestyle choices etc.) causes a longer lifespan, we’d still see the same genetic correlation, even if those genes have no direct effect on lifespan itself. If true, this would still be pleiotropy of a sort: the genes linked to intelligence are having an indirect effect on lifespan. But as the authors acknowledge in their paper, this “pleiotropy-lite” interpretation of the new findings would mean we don’t yet have knockdown evidence for the genetic “system integrity” idea.

So how do we tease apart the two possible explanations for the genetic correlation? In the paper, the authors suggest we study non-human animals (for which the literature on cognitive ability is growing fast) where we can more readily control the “lifestyle” factors, thereby isolating any potential direct effects of the same genes on both intelligence and longevity. Really, though, we might have to wait until we have a long list of genes that are reliably linked to human intelligence. If we knew a good number of those, we could test whether they also influence health and lifespan – if they did, this would be evidence for true “biological” pleiotropy. We’d know then that the link between IQ and lifespan is down to some people simply winning the genetic lottery, rather than to lifestyle factors that any of us could change.

Conflict of interest: Stuart Ritchie is a postdoc in the lab of Ian Deary, one of the co-authors of the paper discussed here.


Arden, R., Luciano, M., Deary, I., Reynolds, C., Pedersen, N., Plassman, B., McGue, M., Christensen, K., & Visscher, P. (2015). The association between intelligence and lifespan is mostly genetic International Journal of Epidemiology DOI: 10.1093/ije/dyv112

further reading
How do you prove that reading boosts IQ?

Post written by Stuart J. Ritchie, a Research Fellow in the Centre for Cognitive Ageing and Cognitive Epidemiology at the University of Edinburgh. His new book, Intelligence: All That Matters, is available now. Follow him on Twitter: @StuartJRitchie

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