Saturday, 22 November 2014

Link feast

Our pick of the best psychology and neuroscience links from the past week or so:

Down The Culinary Rabbit Hole
Over at The Psychologist magazine, Chef Heston Blumenthal describes his work with psychologists,  and there's an exclusive extract from The Perfect Meal: The Multisensory Science of Food and Dining, by Charles Spence and Betina Piqueras-Fiszman (free registration required).

The Best Optical Illusions to Bend Your Eyes and Blow Your Mind – In Pictures
Highlights from the book Eye Benders: The Science of Seeing and Believing, which was recently awarded the Royal Society Young People’s book prize.

What Makes a Terrorist Stop Being a Terrorist?
John Horgan for The Conversation discusses de-radicalisation.

Major Brain Pathway Rediscovered
Mo Costandi reports on new findings concerning a white-matter tract at the back of the brain.

The Self is Moral
"We tend to think that our memories determine our identity," argues Nina Strohminger at Aeon magazine, "but it’s moral character that really makes us who we are."

I Nearly Died. So What?
Meghan Daum at the New York Times draws on her own experiences to challenge the fashionable idea that crises always impart lessons and bring out the best in people.

Ivan Pavlov's Real Quest
A new biography argues that "much of what we thought we knew about Pavlov has been based on bad translations and basic misconceptions," says Michael Specter in the New Yorker.

The "Pink vs Blue" Gender Myth
Claudia Hammond at BBC Future explores whether girls really are born with a preference for pink.

BBC Radio 4's All in the Mind
The latest episode covers problem gambling, a new take on Milgram, plus the latest psychology research discussed by me (the Research Digest Editor).

Personhood Week
All week at her Only Human blog, Virginia Hughes has been exploring what it means to be a person, covering topics such as conception and death.

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

Friday, 21 November 2014

The 100 most followed psychologists and neuroscientists on Twitter

Updated for November 2014, here are the 100 most followed psychologists and neuroscientists on Twitter based on follower counts recorded over the last few weeks. If we've missed anyone (individuals, not organisations) who should be in the top 100, please let us know via comments and we'll add them in to future iterations of the list. This is an update to our February 2014 post. Check the comments to that earlier post for even more psychologists on Twitter than we were able to include here. We're aware there are issues with lists like this (for example, Twitter accounts vary in how many active followers they have), but we hope you find it useful nonetheless. BPS Twitter accounts are presented below, but not counted in the tally towards 100.

Andrew Mendonsa. Clinical psychologist. Followers: 393234
Sam Harris. Neuroscientist, author. Followers: 250966
Kiki Sanford. Neurophysiologist turned sci communicator. Followers: 174275
Steven Pinker. Evolutionary psychologist, author. Followers: 151984
Richard Wiseman. Psychologist, blogger and author. Followers: 135145
Laura Kauffman. Child psychologist. Followers: 106984
Dan Ariely. Behavioural Economist, author. Followers: 81949
Oliver Sacks. Neurologist and author. Followers: 80157
George Huba. Psychologist. Followers: 77181
Leah Klungness. Author and psychologist. Followers: 60591
Travis Langley. Social psychologist and author. Followers: 60043
Dolors Reig. Social psychologist (tweets in Spanish). Followers: 58700
Neuroskeptic. Blogger and neuroscientist. Followers: 47625

BPS Research Digest. The BPS Research Digest! Followers: 46828

Yankı Yazgan. Child psychiatrist/ psychology faculty. Followers: 40381
Melanie Greenberg. Clinical health psychologist. Followers: 38751
Anthony Risser. Neuropsychologist, blogger. Followers: 34450

The Psychologist magazine. Followers: 33234

Dylan William. Educational psychologist. Followers: 32928
Miguel Escotet. Psychologist. Followers: 31948

Marsha Lucas. Neuropsychologist. Followers: 31073
Richard Thaler. Behavioural economist. Followers: 30206
Vaughan Bell. Clinical neuropsychologist, blogger. Followers: 29263

BPS Official. Followers: 26746

Aleks Krotoski. Psychologist, tech journalist. Followers: 24255
Jo Hemmings. Celebrity psychologist. Followers: 23740
Jeremy Dean. Psychology blogger. Followers: 23424
25th place Shawn Achor. Positive psychologist. Followers: 23,330
Amy Cuddy. Social psychologist. Followers: 22837
Kelly McGonigal. Psychologist. Followers: 21733
Mo Costandi. Neuroscience writer, blogger. Followers: 21614
David Dobbs. Neuroscience writer. Followers: 21427
Noah Gray. Neuroscience editor. Followers: 20954

Bob Sutton. Organisational psychologist and author. Followers: 20879
David Eagleman. Neuroscientist, author. Followers: 205714
Dean Burnett. Neuroscientist and comedian. Followers: 18759
David Ballard. Work psychologist. Followers: 18459

Marilyn Price-Mitchell. Developmental Psychologist. Followers: 17652
Dan Gilbert. Psychologist. Followers: 17418
Paul Bloom. Psychologist. Followers: 16957
Sun Wolf. Social neuroscientist. Followers: 16517
Susan Whitbourne. Psychologist. Followers: 16511

Daniel Levitin. Psychologist, author. Followers: 16108
Dorothy Bishop. Developmental neuropsychologist. Followers: 15937
Sarah-Jayne Blakemore
. Cognitive neuroscientist. Followers: 15829
Scott Kaufman. Cognitive psychologist, author. Followers: 15675
Ciaran O'Keeffe. Parapsychologist. Followers: 15504
Melissa McCreery. Clinical Psychologist. Followers: 15394
Heidi GrantHalvorson. Social psychologist. Followers: 15277
Craig Malkin. Clinical psychologist. Followers: 15004
Simon Baron-Cohen. Developmental psychologist. Followers: 148242
Jonathan Haidt. Psychologist. Followers: 14225
50th place Uta Frith. Developmental neuropsychologist. Followers: 13529

Micah Allen. Cognitive neuroscientist. Followers: 12540
Christian Jarrett. Editor of the Research Digest. Followers: 12312

Andrea Letamendi. Clinical psychologist. Followers: 11809

Todd Kashdan. Psychologist. Followers: 11623
Lee Keyes. Psychologist. Followers: 11399
David Webb. Psychology tutor, blogger. Followers: 11369
Honey Langcaster-James. Psychologist and coach. Followers: 11285
Maria Konnikova. Neuroscience blogger and author. Followers: 11182
Petra Boynton. Psychologist, sex educator. Followers: 10960
Professor Bob. Psychologist. Followers: 10783

Tanya Byron. Clinical psychologist, TV presenter, columnist. Followers: 10287
Cary Cooper. Occupational psychologist. Followers: 10275
Pam Spurr. Agony aunt. Followers: 10170
Susan Weinschenk. Psychologist and author. Followers: 10010
David Rock. Work psychologist. Followers: 9995

Maia Szalavitz. Neuroscience journalist. Followers: 9968
Jay Watts. Clinical psychologist, Lacanian. Followers: 9341
Andrea Kuszewski. Robopsychologist. Followers: 9135

Bradley Voytek. Neuroscientist and self-professed geek. Followers: 9002
Timothy Lomauro. Clinical psychologist. Followers: 8996

Stephan Guyenet. Neurobiologist, obesity researcher. Followers: 8795
Jason Goldman. Developmental psychologist, science writer. Followers: 8749
Sophie Scott. Neuroscientist. Followers: 8722

Cheryl Arutt. Clinical and forensic psychologist. Followers: 8690
75th place Margarita Holmes. Psychologist and sex therapist. Followers: 8689
Claudia Hammond. Radio presenter. Followers: 8430
Neuro Bonkers. Blogger. Followers: 8397
Todd Finnerty. Psychologist. Followers: 8066
Bruce Hood. Cognitive scientist. Followers: 7870

Steven Novella. Neurologist and sceptic. Followers: 7635
Graham Jones. Internet (cyber) psychologist. Followers: 7529

John Grohol. Founder of Psychcentral. Followers: 6814
Shelley Bonanno. Psychologist and psychotherapist. Followers: 6549
Jay Dadlani. Psychologist. Followers: 6361
Rory O'Connor. Health psychologist, suicide researcher. Followers: 6292
Jesse Bering. Psychologist, blogger. Followers: 6239

Kevin Mitchell. Neurogeneticist. Followers: 6230
Kathleen Young. Clinical Psychologist. Followers: 5930

Gary Marcus. Psychologist, author and blogger. Followers: 5923
Hugo Spiers. Neuroscientist. Followers: 5817
Andy Field. Psychologist and stats whiz. Followers: 5737
Marco Iacoboni. Neuroscientist, mirror neuron expert. Followers: 5727
Earl Miller. Cognitive neuroscientist. Followers: 5661
Steven Brownlow. Clinical and forensic psychologist. Followers: 5574
G. Tendayi Viki. Social psychologist. Followers: 5564
Judith Beck. Clinical psychologist. Followers: 5447
Lyle Becourtney. Specialist in anger management. Followers: 5413
Neurocritic. Blogger. Followers: 5297
Jon Sutton. Editor of The Psychologist. Followers: 5236
100th place Molly Crockett. Neuroscientist. Followers: 5204

Thanks to Emma Smith at the BPS for updating the follower counts

Thursday, 20 November 2014

Bankers become dishonest when reminded of their professional identity

The "Natwest 3" jailed
for wire fraud in 2008.
Picture a banker tossing a coin ten times. She knows the more tails she gets, the more money she wins (up to $200), so long as she gets more tails than a rival playing the same game. She performs her coin tossing in private and reports her number of tails. Do you think she'll be honest?

When a team of researchers surveyed the general population about the likely dishonesty of bankers and other groups in this scenario, they found the bankers had the worst reputation, even compared with prison inmates. On average, the public thought that bankers would exaggerate their performance by 27 per cent.

What's the reality? Alain Cohn and his colleagues tested 128 employees from a large international bank on the coin flipping task, including private bankers, asset managers, traders, and support staff such as those in HR and risk management (61 per cent were male). Crucially, half were reminded of their professional identity through questions about where they worked and what their duties were. The other half were asked irrelevant questions, such as how much TV they watch.

The bankers asked the irrelevant questions played mostly honestly - on average, they didn't report performing any better than you'd expect given the probabilities involved in flipping a coin. By contrast, the bankers who were reminded of their professional identity displayed inflated levels of dishonesty - exaggerating their success by 16 per cent, on average. Not as bad as the public had anticipated, but still high, and it's worrying that it was reminders of being a banker that led to this level of cheating.

It's not just that being reminded of one's professional identity leads anyone to become more dishonest. The researchers checked this by repeating the experiment with participants from a range of professions including IT and pharmaceuticals. Being reminded of their professional identity made no difference to the honesty of these participants.

Maybe it's just that thinking about being a banker prompts bankers to think of money, which is known to inspire competitiveness and selfishness? Not so - when the coin flipping task was repeated with university students, those asked to name a bank, and to describe banking duties, did not become more dishonest.

Further tests also ruled out the possibility that being reminded of their professional identity led bankers to feel more competitive, or to think that other bankers are more dishonest (both of which might have provoked them to cheat in the coin game).

Instead, the reason that a banker's professional identity encourages him or her to behave more dishonestly appears related to the materialistic culture fostered in that world. Cohn and his team found that bankers prompted to think about their professional identity tended to agree with the statement that social status is primarily determined by financial success, more than did bankers who were not primed in this way (they were asked irrelevant questions instead). Also, greater endorsement of this materialistic view correlated with more dishonesty in the coin game.

"These findings substantiate current concerns about the influence of materialistic values in the banking sector," the researchers said, "and indicate that the professional identity prime may have increased dishonesty through an increase in materialistic values."

Dishonesty and unscrupulous behaviour in the banking world contributed to the recent financial crisis, and the dire reputation of bankers continues to undermine confidence in our financial institutions. This new research provides some of the first empirical evidence for why bankers stray from integrity.

"Our results suggest that banks should encourage honest behaviours by changing the norms associated with their workers' professional identity," the researchers concluded. "For example, several experts and regulators have proposed that bank employees should take a professional oath analogous to the Hippocratic oath for physicians."


Alain Cohn, Ernst Fehr, & Michel Marechal (2014). Business culture and dishonesty in the banking industry Nature.

--further reading--
Threaten a man's masculinity and he becomes a short-sighted risk taker
The cheater's high - how being bad feels good
Does greater competition improve performance or increase cheating?
Psychologically safe teams can incubate bad behaviour

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

Wednesday, 19 November 2014

Do you remember the time? How collective nostalgia inspires group loyalty

Nostalgia seems like a distraction in a world that’s moving forward. But new research proposes a powerful function of the emotion: as a glue to bind members of social groups.

Students from the University of Southampton recalled and wrote about an experience either involving other students, or where they were alone. They were either asked to choose an ordinary event or one that triggered nostalgic feeling, defined in the instructions as "sentimental longing for the past".

Next they were asked how many hours they would be prepared to invest in a publicity campaign for the university. Most willing to help were those who had recalled a nostalgic memory involving other students, because (according to a post-study survey) it made them  prize their student identity more highly.

Could these intentions just be the result of a better mood? Unlikely; although textual analysis showed the nostalgic memory descriptions were more positive, across all conditions positivity was no indicator of intention to volunteer. Moreover, another experiment showed that recalling a collective "fortunate event" did not lead to more good intentions towards other students, even though these memories were very positive. Lead author Tim Wildschut points out that nostalgia is distinctive in part because it blends both positive and wistful features, and that it is this longing that makes it a more active emotion than amusement or satisfaction, inspiring people to want to revisit or protect the things that trigger it.

Nostalgia alters how people say they will behave, but is that just talk? A follow-up experiment indicated otherwise. After a nostalgic or ordinary recall of a collective event, Irish participants were given a set amount of tokens and then asked to observe a token-sharing transaction between an Englishman and an Irishman. When they saw the Englishman make an unfair offer, the participants had the chance to punish him, but at their own cost in tokens. Choosing to punish the unfair English player was taken as a sign of in-group loyalty.

Nostalgia encouraged more self-sacrifice for the group, but only in some participants. Specifically, those who strongly identified as Irish from the outset of the study sacrificed nearly half their stash for a stranger. Those who felt less affiliated sacrificed a fifth, which was no more vengeful than those without a nostalgia induction. Wildschut notes that direct effects of emotion onto specific behaviours are generally much weaker than intentions, because participants might find other ways to act outside of the confines of the study.

Rather than being without function, it appears that nostalgia is an organising emotion, strengthening group membership and developing collective identities. It can be used to ugly ends: politicians appealing to mythical pasts to paint outsiders as threats. But it may also help migrants to maintain solidarity and meaning in new environments that can be hostile or non-inclusive. And for any of us, giving in to a nostalgic impulse may be enough to inspire picking up a phone and making contact with people we've been apart from for too long.


Wildschut, T., Bruder, M., Robertson, S., van Tilburg, W., & Sedikides, C. (2014). Collective nostalgia: A group-level emotion that confers unique benefits on the group. Journal of Personality and Social Psychology, 107 (5), 844-863 DOI: 10.1037/a0037760

--further reading--
Feeling chilly? Indulge in some nostalgia
Nostalgia - from cowbells to the meaning of life
Post written by Alex Fradera (@alexfradera) for the BPS Research Digest.

Monday, 17 November 2014

Why you're particularly likely to run your first marathon when your age ends in a "9"

When we look at our lives, we tend to break them up into chapters, rather like the seasons of a TV box set. Potential dividers come in many forms, including the dawn of a new year, or the start of a new job. But if those events act as a marker between episodes, it is the decades of our lives that represent the more profound end of one series or season and the start of the next.

According to the psychologists Adam Alter and Hal Hershfield, when we're on the cusp of one of these boundaries - in other words, when our age ends in a "9", such as 29, 39, 49 or 59 - we are particularly prone to reflect on the meaning of our lives. If we don't like what we see, their new results suggest we take drastic action, either fleeing life's emptiness, or setting ourselves new goals.

The pair began by looking at data from the World Values Survey. Based on answers from 42,063 adults across 100 nations, they found that people with an age ending in 9 (the researchers call these people "9-enders") were more likely than people of other ages to say that they spent time thinking about the meaning and purpose of their lives.

In another study, participants prompted to imagine and write about how they would feel the night before entering a new decade, tended to say they would think about the meaning of their life more than did other participants who'd been prompted to write about the night before their next birthday, or to write about tomorrow.

At the dawn of a new decade, how does this focus on life's meaning affect our behaviour? Alter and Hershfield say that for some people it can lead to "maladaptive behaviours". They looked at data from an online dating website that caters for people who are seeking extramarital affairs. Among over 8 million male users of the site, 9-enders were over-represented by 17.88 per cent relative to what you'd expect if participation were randomly distributed by age. The same was true, though to a lesser extent, for female users of the site.

For some people, the self-reflection triggered by the prospect of entering a new decade is more than they can bear. Alter and Hershfield also examined suicide data collected between 2000 and 2011 by the US Center for Disease Control and Prevention. They found that 9-enders take their own lives with a greater frequency than people whose ages end in any other digit.

It seems the "crisis of meaning" triggered by the prospect of a new decade can also lead people to set themselves new goals. When the researchers looked at data on the Athlinks website, they found that among 500 first-time marathon runners, 9-enders were over-represented by 48 per cent. The same site also contained evidence of 9-enders investing greater effort into their training and performance. Focusing on data from runners in their twenties, thirties and early forties who'd run a marathon at the end of a decade and also in the preceding and following two years, the researchers found that people achieved better times, by an average of 2.3 per cent, when they were aged 29 or 39 than when they were one or two years younger.

The researchers said there's a growing literature that suggests "although people age continually, the passage of time is more likely to influence their thoughts and actions at some ages than others." They added: "Here we find that people are significantly more likely to consider whether their lives are meaningful as they approach the start of a new decade."


Alter, A.L., & Hershfield, H.E. (2014). People search for meaning when they approach a new decade in chronological age PNAS

--further reading--
The taste for competition peaks at age 50
The boxed set approach to setting goals

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

How guessing the wrong answer helps you learn the right answer

Guessing, even wrongly, is thought to
activate webs of knowledge, which leads
to richer encoding of the correct answer. 
It's well known that taking tests helps us learn. The act of retrieving information from memory helps that information stick. This seems intuitive. More surprising is the recent discovery that guessing aids subsequent learning of the correct answer, even if your initial guess was wrong.

Let's consider a simple example in the context of learning capital cities. Imagine you don't know the capital of Brazil. In the first scenario, I show you the word Brazil and your task is to say the capital. Because you don't know, you guess "Rio de Janeiro". This guessing phase takes 8 seconds. I then show you, for 5 seconds, the word Brazil together with the correct answer "Brasilia". In the second scenario, you simply have 13 seconds to study the country/capital pairing Brazil and Brasilia.

Later on, I test you on the capital of Brazil. The new research on guessing finds that you're more likely to recall the correct answer in the first scenario, in which you initially guessed wrong. This is counter-intuitive for two reasons - first, you had less time to study the correct information (5 seconds vs. 13 seconds), and second, you came up with a wrong answer, which you'd think would interfere with your memory for the correct answer once I gave it to you.

How can this be? A new study by Veronica Yan and her colleagues at the University of California, Los Angeles, puts two possibilities to the test. To understand the first of these, we need to realise that prior research on the guessing effect has tended to use word pairs related by meaning, such as "olive" and "branch" or "whale" and "mammal". Some participants simply study the word pairs, others guess each partner word before being shown the correct word. The guessing process leads to superior memory for the word pairs than simply studying them, even when the guessing is wrong.

Crucially, this past research has tended to use word pairs only weakly related in meaning, while the participants in the guessing condition usually guess strongly related words. Yan and her colleagues reasoned that this could be a way for the guessing process to be a memory aid. When it comes to the memory test on the word pairs, participants in the guessing condition can use the rule of the thumb "the correct answer is always weakly related to the first word". This is a shrewd observation on the part of Yan and her team, but they found no evidence support their theory. The beneficial guessing effect still occurred even when they used a mix of strongly and weakly related word pairs.

The second explanation Yan's team tested had to do with whether a person's guesses are always wrong. If the initial guess is always wrong, perhaps this makes it easy to always suppress the guess information, thereby aiding recall of the correct answer once it's given. Yan's team also found this explanation wanting. Participants still benefited from the guessing effect even when the procedure was rigged so that half their guesses were right and half were wrong.

Yan et al's final study examined the duration of the beneficial guessing effect. They reasoned that perhaps the benefit will only be short-lived, while participants are easily able to remember and suppress their guessed answer. In fact the learning benefits of guessing, even incorrectly, was found even when participants were tested 61 hours after the guessing process.

So why does guessing have this beneficial effect for learning? The truth is we still don't really know. An explanation with growing support has to do with what psychologists call "semantic activation". Essentially they're saying that guessing activates the mental web of knowledge and facts associated with the correct answer, which makes the subsequent storage of that correct information easier once it's given. "The basic idea is that this [guessing-related] activation ... affords a richer encoding of the subsequently presented target," the researchers said.

From a practical perspective, this research on the beneficial effects of guessing suggests that teachers shouldn't worry too much about giving students tests that are too difficult. Even if they keep getting the answers wrong, so long as they're given the correct information afterwards, the act of guessing is actually likely to assist their learning, not hinder it.


Yan, V., Yu, Y., Garcia, M., & Bjork, R. (2014). Why does guessing incorrectly enhance, rather than impair, retention? Memory & Cognition, 42 (8), 1373-1383 DOI: 10.3758/s13421-014-0454-6

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

Saturday, 15 November 2014

Link feast

Our pick of the best psychology and neuroscience links from the past week or so:

Winter Is a Black Hole: How I Deal With Seasonal Depression
"Seasonal depression hits for me, like clockwork, the day after Halloween" - writes Dayner Evans at

Learning How Little We Know About the Brain
By James Gorman in the New York Times.

How To Debunk Falsehoods
At BBC Future, Tom Stafford investigates the best way to correct false ideas.

The “Paper Effect” – Note Something Down And You’re More Likely To Forget It
At the Brain Watch blog I lampoon fears about the effect of computers and other digital devices on our memories.

How to Be Efficient: Dan Ariely’s 6 New Secrets to Managing Your Time
At Time magazine, Eric Barker summarises time-keeping advice from the author of Predictably Irrational.

I Hated Keeping a Gratitude Journal - Here's What Worked Instead
Allison Jones at

Fooled By Your Own Brain
Don't be so certain your senses are telling you the truth, says Virginia Hughes at Nautilus.

Human Body: The "Ultra-athletes" aged 60+
At BBC Future, David Robson reports on the senior ultra-athletes who are defying the limits of aging and the body.

Living With Schizophrenia
Access 60 free journal articles on this topic, courtesy of Psychology Press / Taylor and Francis.

How to Study The Brain
We're about to obtain unprecedented amounts of new data on the brain, says Gary Marcus at The Chronicle, but the important missing ingredient is theory.

Illustrations of Madness: James Tilly Matthews and the Air Loom
At the Public Domain Review, Mike Jay recounts the tragic story of James Tilly Matthews, who was confined to Bedlam asylum in 1797 for believing that his mind was under the control of a terrifying machine.
Post compiled by Christian Jarrett (@psych_writer) for the BPS Research Digest.

Friday, 14 November 2014

Reformers say psychologists should change how they report their results, but does anyone understand the alternative?

The rectangular bars indicate sample
means and the red lines represent the
confidence intervals surrounding them.
Image: Audriusa/Wikipedia
Psychological science is undergoing a process of soul-searching and self-improvement. The reasons vary but include failed replications of high-profile findings, evidence of bias in what gets published, and surveys suggestive of questionable research practices.

Among the proposed solutions is that psychologists should change the way they report their findings. Traditionally, most research papers report a "p value" that indicates whether the results are statistically significant or not. Critics say this approach encourages "p hacking" - tweaking the experimental protocol until the results reach the magic threshold of significance.

An alternative approach proposed by some reformers is to report "confidence intervals" - these indicate an upper and lower range within which the true mean score might lie (the "true mean" here refers to the average score or measure of a population, as opposed to the average score of your particular sample. Imagine sampling the height of 100 men to try to estimate the "true" average height of men in the country).

Confidence intervals are less prone to misinterpretation, say advocates, and they help avoid dichotomous thinking - the idea that a result is either significant or it isn't. The American Psychological Association strongly endorses the use of confidence intervals.

Now a group of psychologists in The Netherlands has tested whether confidence intervals really are as well understood as their supporters claim. Rink Hoekstra and his colleagues surveyed 442 first-year psychology students who had yet to complete any statistics classes; 34 masters students; and 120 psychology researchers including doctoral students and lecturers.

All the participants were presented with a basic research premise:
Professor Bumbledorf conducts an experiment, analyses the data, and reports: "The 95% confidence interval for the mean ranges from 0.1 to 0.4!"
The participants were then presented with six statements that follow from Bumbledorf's result. In each case they had to indicate whether the statement was true or false. They were told that it was possible all the statements were true, all were false, or that there was a mix of true and false. Here are three of them:
  • The probability that the true mean is greater than 0 is at least 95%
  • There is a 95 per cent probability that the true mean lies between 0.1 and 0.4
  • If we were to repeat the experiment over and over, then 95% of the time the true mean falls between 0.1 and 0.4
In actual fact all six of the statements were false, and the alarming result is that many were incorrectly endorsed, not just by the students but also by the established psychology researchers. On average, the first-year students endorsed 3.51 statements, the masters students 3.24, and the researchers 3.45. The survey also included a question about experience with statistics. Participants who reported more experience of statistics endorsed just as many of the false statements.

The correct interpretation of Bumbledorf's statement is that in 100 samples obtained using his methods, you would expect the true value of the mean to lie in the 95 per cent confidence interval for 95 of those samples. Note that each sample would have its own interval (i.e its own upper and lower limit), a fact which is inconsistent with the three test statements shown above.

Hoekstra and his colleagues said their results showed "dramatic and similar levels of misinterpretation among both researchers and students." They added: "One could question whether our findings indicate a serious problem in scientific practice, rather than merely an academic issue. We argue that they do indicate a serious problem, one closely related to what some authors refer to as a crisis in the social and behavioural sciences."


Hoekstra, R., Morey, R., Rouder, J., & Wagenmakers, E. (2014). Robust misinterpretation of confidence intervals Psychonomic Bulletin & Review, 21 (5), 1157-1164 DOI: 10.3758/s13423-013-0572-3

--further reading--
Made it! An uncanny number of psychology findings manage to scrape into statistical significance

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