Scanning a brain that believes it is dead

What is going on in the brain of someone who has the deluded belief that they are brain dead? A team of researchers led by neuropsychologist Vanessa Charland-Varville at CHU Sart-Tilman Hospital and the University of Liege has attempted to find out by scanning the brain of a depressed patient who held this very belief.

The researchers used a Positron Emission Tomography (PET) scanner, which is the first time this scanning technology has been used on a patient with this kind of delusion - known as Cotard's syndrome after the French neurologist Jules Cotard. The 48-year-old patient had developed Cotard's after attempting to take his own life by electrocution. Eight months later he arrived at his general practitioner complaining that his brain was dead, and that he therefore no longer needed to eat or sleep. He acknowledged that he still had a mind, but (in the words of the researchers) he said he was "condemned to a kind of half-life, with a dead brain in a living body."

The researchers used the PET scanner to monitor levels of metabolic activity across the patient's brain as he rested. Compared with 39 healthy, age-matched controls, he showed substantially reduced activity across a swathe of frontal and temporal brain regions incorporating many key parts of what's known as the "default mode network". This is a hub of brain regions that shows increased activity when people's brains are at rest, disengaged from the outside world. It's been proposed that activity in this network is crucial for our sense of self.

"Our data suggest that the profound disturbance of thought and experience, revealed by Cotard's delusion, reflects a profound disturbance in the brain regions responsible for 'core consciousness' and our abiding sense of self," the researchers concluded.

Unfortunately the study has a number of serious limitations beyond the fact that it is of course a single case study. As well as having a diagnosis of Cotard's Delusion, the patient was also depressed and on an intense drug regimen, including sedative, antidepressant and antipsychotic medication. It's unclear therefore whether his distinctive brain activity was due to Cotard's, depression or his drugs, although the researchers counter that such an extreme reduction in brain metabolism is not normally seen in patients with depression or on those drugs.

Another issue is with the lack of detail on the scanning procedure. Perhaps this is due to the short article format (a "Letter to the Editor"), but it's not clear for how long the patient and controls were scanned, nor what they were instructed to do in the scanner. For example, did they have their eyes open or closed? What did they think about?

But perhaps most problematic is the issue of how to interpret the findings. Does the patient have Cotard's Delusion because of his abnormal brain activity, or does he have that unusual pattern of brain activity because of his deluded beliefs? Relevant here, but not mentioned by the researchers, are studies showing that trained meditators also show reduced activity in the default mode network. This provides a graphic illustration of the limits to a purely biological approach to mental disorder. It seems diminished activity in the default mode network can be associated both with feelings of being brain dead or feelings of tranquil oneness with the world, it depends on who is doing the feeling. Understanding how this can be will likely require researchers to think outside of the brain.

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Charland-Verville, V., Bruno, M., Bahri, M., Demertzi, A., Desseilles, M., Chatelle, C., Vanhaudenhuyse, A., Hustinx, R., Bernard, C., Tshibanda, L., Laureys, S., and Zeman, A. (2013). Brain dead yet mind alive: A positron emission tomography case study of brain metabolism in Cotard's syndrome. Cortex DOI: 10.1016/j.cortex.2013.03.003

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

Stand by me: Close friendships appear to counteract genetic vulnerability to depression in girls, but not boys

Publication of US psychiatry's updated diagnostic code has provoked renewed debate in recent weeks over the extent to which mental illness ought to be framed as a psychosocial or a biological problem. The answer of course is that it is both. A new Canadian study captures this interplay, showing how close friendships appear to mitigate the risk for girls whose genes mean they are more vulnerable than average to depression.

Mara Brendgen and her colleagues studied 294 pairs of twins aged ten years old (147 girls). Some of the twins were identical (they share the same genes), the others were non-identical (sharing just half their genes). Each twin pair was raised together in the same family.

The researchers obtained ratings of the children's signs of depression from their teachers and classmates. They also gauged their close friendships by asking each child to nominate up to three best friends in their class, and to indicate who was their very best friend. Reciprocal nominations were a sign of mutual friendship. The children also answered questions about the quality of their friendships, including whether they do fun things together or get angry with each other.

Consistent with past research, there was evidence of the role of genes in depression. That is, correlations in signs of depression were much higher between identical versus non-identical twins. If one of a pair of identical twins had signs of depression, this was taken as an indication that the second twin had genetic vulnerability for the condition. If one of a pair of non-identical twins showed signs of depression, this was also taken to mean the other twin had genetic vulnerability, but less so than in the case of identical twins.

Here's the main result. Genetic vulnerability to depression in girls was less likely to manifest if they had at least one close friend. Stated differently, the apparent protective effect of having at least one close friend was magnified in girls who were genetically vulnerable to the condition. This means that for girls there was an interplay between genetic risk and the protective effect of friendship. This was not the case for boys. Friendships did appear to protect boys from depression, but this was not related in any way to their genetic vulnerability. Perhaps, the researchers surmised, there is a gender difference because "girls tend to rely more on social relationships as a source of self-definition and self-validation, and their friendships are also characterised by greater intimacy, self-disclosure, empathy and emotional support."

Separate from any issues of genetic vulnerability, another gender difference was that boys, but not girls, showed an apparently additive protective effect against depression of having more friends. The researchers said this may be because girls more often have intimate one-on-one friendships, whereas boys are more often part of friendship groups.

Other details to emerge from the study: better quality friendships were more protective against depression (regardless of genetic vulnerability); genetic vulnerability to depression wasn't associated with the likelihood of a child having friends, but it was negatively associated with the perceived quality of their friendships.

The study has some limitations, particularly the relatively small sample size, the reliance on observer ratings of depression, and the cross-sectional design, which means a causal role for friendships cannot be assumed. It's possible that the manifestation of depression symptoms in genetically vulnerable girls leads to fewer friends, rather than more friends reducing signs of depression (note however that social support is a known mitigating factor against depression). Also, the results may be specific to this age group.

Despite these shortcomings, this is an innovative study on an important topic. Children who show signs of depression pre-adolescence are at heightened risk for having problems in their teens and beyond, so the more we understand about mitigating this risk, the better. The researchers said their results "emphasise the importance of  teaching social interactional skills that promote positive relations with others to help prevent the development of depressive behaviour in children."

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Brendgen, M., Vitaro, F., Bukowski, W., Dionne, G., Tremblay, R., and Boivin, M. (2013). Can friends protect genetically vulnerable children from depression? Development and Psychopathology, 25 (02), 277-289 DOI: 10.1017/S0954579412001058

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

Link feast

In case you missed them - 10 of the best psychology links from the last week:

1. How too much empathy can actually lead us to do the wrong thing - thought-provoking essay by Paul Bloom. (related research covered on the Digest).

2. Thanks to books like Daniel Kahneman's Thinking Fast and Slow and, most recently, Rolf Dobelli's The Art of Thinking Clearly, hundreds of thousands, if not millions, of people are discovering the manifold biases that muddle human judgment. So how come there hasn't been a revolution in good sense and shrewd decision making? Samuel McNerney may have the answer.

3. The Digest nearly won an award this week (hold the applause), reaching finalist position for psychology/neuroscience in the inaugural Science Seeker blogging awards. Many congratulations to all the winners, especially to Aatish Bhatia winner of the psych/neuro category; to psychologist Pete Etchells who won "best post about peer-reviewed research"; and to Virginia Hughes, who won "post of the year" for her superb story about hypersomnolence.

4. The build up to the release of US psychiatry's updated diagnostic code (DSM-5) continued this week as the BPS Division of Clinical Psychology published a statement calling for a "paradigm shift" in psychiatric diagnosis "away from an outdated disease model" towards "an approach which pays far more attention to the complex range of life experiences of people experiencing mental distress."

5. The story broke at the Observer on Sunday with an unfortunate spin that implied psychology was at war with psychiatry. Professor Sir Simon Wesseley, a psychiatrist, showed there is in fact a great deal of consensus ("Mindless psychiatry is as unhelpful as brainless psychiatry, and the psychiatrist who ignores the social environment is, well, not a psychiatrist").

6. How to spot a murderer's brain (or not).

7. Ed Yong reported on an ambitious and controversial new study of super-brainy participants that's looking to pin down the genetic influences on intelligence.

8. Do nice guys really finish last?

9. If only there were somewhere you could get an expert, no-nonsense discussion of psychology research that's been splashed all over the media ... hang on, psychologist and writer Tom Stafford has started a new column for The Conversation that does just that - first off, can a poster of staring eyes really deter bike thieves?

10. The 2013 illusion of the year has been chosen - check out the winner and runners up.

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

Experienced job interviewers are no better than novices at spotting lying candidates

For the penultimate round of the TV show The Apprentice, the competing entrepreneurs must face a series of interviews with a crack team of hardened executives. The implicit, believable message is that these veterans have seen all the interview tricks in the book and will spot any blaggers a mile off. However, a new study provides the reality TV show with a reality check. A team led by Marc-André Reinhard report that experienced job interviewers are in fact no better than novice interviewers at spotting when a candidate is lying.

The researchers filmed 14 volunteers telling the truth about a job they'd really had in the past and then spinning a yarn about time in a job they'd never really had. The volunteers were offered a small monetary reward to boost their motivation. These clips were then played online to 46 highly experienced interviewers (they'd conducted between 21 and 1000 real-life job interviews), 92 interviewers with some experience (they'd interviewed at least once), and 214 students who'd never before acted as a job interviewer. The participants' task was to identify the clips in which the interviewee was speaking truthfully about their work experience, and the clips in which the interviewee was fabricating.

Overall the participants achieved an accuracy rate of 52 per cent - barely above chance performance, which is consistent with a huge literature showing how poor most of us are at spotting deception. But the headline finding is that the more experienced interviewers were no better than the novice interviewers at spotting lying job candidates - the first time that this topic has been researched. Greater work seniority, having more work experience and having more subordinates at work were also unrelated to the ability to spot lying job candidates.

There was a glimmer of hope that interview lie-detection skills could be taught. Participants who reported more correct beliefs about non-verbal cues to lying (e.g. liars don't in fact fidget more) were slightly more successful at recognising which job candidates were lying (each correct belief about a non-verbal cue added 1.2 per cent more accuracy on average). Experienced and novice interviewers in the current study didn't differ in their knowledge about lying cues, which helps explain why the veterans were no better at the task. The more experienced interviewers were however more skeptical overall, tending to rate more of the clips as featuring lying.

"Our results provide the first evidence that employment interviewers may not be better at detecting deception in job interviews than lay persons," the researchers said, "although it is a judgmental context that they are very experienced with."

Although the main gist of the results is consistent with related research in other contexts - for example, studies have found police detectives are no better at spotting lies, despite their interrogation experience - this study has some serious limitations, which undermine the applicability of the findings to the real world. Above all, the study did not involve real interviews, which meant the participants were unable to interact with the interviewees in a dynamic manner.

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Reinhard, M., Scharmach, M., and Müller, P. (2013). It's not what you are, it's what you know: experience, beliefs, and the detection of deception in employment interviews Journal of Applied Social Psychology, 43 (3), 467-479 DOI: 10.1111/j.1559-1816.2013.01011.x

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

Engaging lecturers can breed overconfidence

Do fluent presenters make
learning feel too easy?

Eloquent and engaging scientific communicators in the mould of physicist Brian Cox make learning seem fun and easy. So much so that a new study says they risk breeding overconfidence. When a presenter is seen to handle complicated information effortlessly, students sense wrongly that they too have acquired a firm grasp of the material.

Shana Carpenter and her colleagues showed 42 undergrad students a one-minute video of a science lecture about calico cats. Half of them saw a version in which the female lecturer was confident, eloquent, made eye-contact and gestured with her hands. The other students saw a version in which the same lecturer communicated the same facts, but did so in a fumbling style, frequently checking her notes, making little eye contact and few gestures.

After watching the video, the students rated how well they thought they'd do on a test of its content ten minutes later. The students who'd seen the smooth lecturer thought they would do much better than did the students who saw the awkward lecturer, consistent with the idea that a fluent speaker breeds confidence. In fact, both groups of students fared equally well in the test. In the case of the students in the fluent lecturer condition, this wasn't as good as they'd predicted. Their greater confidence was misplaced.

A second study was similar - 70 students watched either a fluent or fumbling lecturer, but this time the students had a chance afterwards to spend as long as they wanted reviewing the script. On average, both groups of students devoted the same amount of time (perhaps out of habit). But only among the students who'd watched the fumbling lecturer was there a link between time spent on the script and subsequent performance on the test. This suggests only they used the time with the script to fill in blanks in their knowledge.

"Learning from someone else - whether it is a teacher, a peer, a tutor, or a parent - may create a kind of 'social metacognition'," the researchers said, "in which judgments are made based on the fluency with which someone else seems to be processing information. The question students should ask themselves is not whether it seemed clear when someone else explained it. The question is, 'can I explain it clearly?'".

An obvious limitation of the study is the brevity of the science lecture and the fact it was on video. It remains to be seen whether this result would replicate in a more realistic situation after a longer lecture. Also, in real life, there may be costs to a fumbling lecture style that weren't picked up in this study, such as students mind wandering and skipping class.

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Carpenter, S., Wilford, M., Kornell, N., and Mullaney, K. (2013). Appearances can be deceiving: instructor fluency increases perceptions of learning without increasing actual learning. Psychonomic Bulletin and Review DOI: 10.3758/s13423-013-0442-z

--Further reading--
Co-author on this study, Nate Kornell, wrote a guest Digest post in 2008 with study tips for students. 
How fluency affects judgement, choice and processing style

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.
Image: Paul Clarke Wikipedia Commons. 

Occupational hazard - links between professions and suicide risk have changed over time

Suicide rates have fallen among farmers

Among the various risk factors for suicide, psychologists have recognised for some time that a person's occupation plays an important part. Suicide rates have tended to be unusually high in professions that provide ready access to guns, drugs, or open water, such as in farming, medicine, dentistry and maritime careers.

A new analysis has examined whether this still holds true. Stephen Roberts and his colleagues accessed the UK suicide rates for dozens of occupations in 1979 to 1983 and compared these with similar data recorded between 2001 and 2005.

Consistent with the ready access theory, vets, pharmacists, dentists, doctors, and farmers were all among the top 15 occupations with the highest suicide rates back in the late 70s, early 80s. But this had all changed when looking at the more recent data. In the early noughties, none of these professions were in the top 30 occupations in terms of suicide rates. Instead, the occupations with the highest rates of suicide were largely manual, including coal miners, builders, window cleaners, plasterers and refuse collectors.

Stated differently, of 55 high-risk occupations, 14 had shown reductions in suicide rate in the noughties compared with the late seventies, and these were almost exclusively highly educated professional roles like doctors, radiographers and judges, as well as farmers, actors and authors. In contrast, five of the 55 high-risk professions showed an increased rate of suicide in the later data, and these were exclusively manual professions - coal miners, labourers, plasterers, fork-lift drivers and carpenters.

The new findings are published at a time when arguments are raging over the relative prominence that should be given to biological or social explanations of mental illness.

According to this new analysis, socio-economic forces appear to have become an increasingly major factor in occupational suicide risk. The percentage of variation in suicide rates explained by an occupation's socioeconomic grouping (e.g. managerial, trade, admin etc) almost doubled from 11.4 per cent in the early data to 20.7 per cent in the early noughties. Bear in mind these figures were from before the recession, so if anything it seems likely this trend will have intensified in more recent years.

The data also showed that suicide rates were much higher among men than women, and that among men, the most at-risk occupations tended to be manual, whereas in women they were more often (non-manual) professional.

If the pattern of these results are replicated in other European and Western countries, the researchers said this "could help in developing new suicide prevention interventions that can be targeted at specific occupational groups."

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Roberts, S., Jaremin, B., and Lloyd, K. (2013). High-risk occupations for suicide Psychological Medicine, 43 (06), 1231-1240 DOI: 10.1017/S0033291712002024

--Further reading--
More Digest reports on suicide.
Men, suicide and society - why disadvantaged men in mid-life die by suicide (Samaritans report).

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

Link feast

In case you missed them - 10 of the best psychology links from the past week:

1. Love this - "Neuroscience may be sexier than psychology right now, and it certainly has a lot more money and celebrity. But they really cannot get along without each other." Alison Gopnik in the Wall Street Journal on How The Brain Really Works.

2. New Scientist has started a new column written by people with "mysterious neurological conditions". The first is by Heather Sellers who has a severe form of prosopagnosia (AKA face blindness).

3. There's been lots of coverage this last week about NIMH director Thomas R. Insel's announcement that his organisation - the world's largest funder of mental health research - will be moving away from US psychiatry's DSM categories, just as the profession is about to publish the latest version of its diagnostic manual. My favourite round-up of the affair was by Christopher Lane for Psychology Today. Other bloggers pointed out that the big news isn't really that surprising at all. (also, check out this measured response from the chair of DSM5).

4. "Probably the most boring book in the world" - that's how Prof Sir Simon Wesseley described the DSM on the latest edition of BBC Radio 4's All in the Mind as he told presenter Claudia Hammond that the diagnostic code really isn't that relevant here in the UK. The programme also covered recent research that looked at rates of crying by therapists in therapy (check out my coverage of the research earlier this year).

5. The Guardian covered the psychological tricks that restaurant menu-compilers use to influence your dinner order.

6. Newly posted TED talk by positive psychology researcher Angela Lee Duckworth: The key to success? Grit.

7. A new play on tour in the UK "Mess" sets out to demystify anorexia and it's getting rave reviews. It's written by and stars Caroline Horton, who has first-hand experience of the condition. (There's also a new book out soon about anorexia: Ministry of Thin, How the Pursuit of Perfection Got Out of Control).

8. I enjoyed this charming account of the decades-long research relationship between Suzanne Corkin and amnesiac Henry Molaison. (Corkin's new book about Molaison is out now in hardback and Kindle).

9. Nathan Azrin, the psychologist who pioneered the use of "token economies" on psychiatric wards has died aged 82. "It would be difficult to name a population that wasn’t affected by his work," said Alan Kazdin in this NYT obituary.

10. Bad news for "Tiger" parenting enthusiasts - "Children of parents ... classified as “tiger” had lower academic achievement and attainment—and greater psychological maladjustment—and family alienation, than the kids of parents characterized as “supportive” or "easygoing.”

--
Looking ahead to the weekend and beyond. There's a workshop this Saturday and Sunday in London on Havening Therapy, which promises to cure trauma in minutes. Here's why I won't be going. Later in the week in Oxford, there are still tickets available for three Pint of Science brain-related events.

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

Children aren't scared by nasty dentist visits, but by what they think of them

The Greek Stoic Epictetus wrote that "Men are disturbed not by things, but by the view which they take of them." A new study involving 185 children and teenagers, 88 fathers and 97 mothers shows how this same principle applies to children's fear of the dentist. This is an important topic because many children avoid the dentist out of fear, and around half of dentally anxious adults trace their fears to childhood.

Antonio Crego and his colleagues assessed the children's fear of the dentist, any bad experiences they'd had, their personality, their relatives' fear and, most importantly for this study, their "cognitive vulnerability". This last measure looked at how much the children had feelings of uncontrollability (e.g. feeling trapped), unpredictability (not knowing what will happen), dangerousness (expecting pain) and disgustingness (expecting it to turn their stomach) about a visit to the dentist. The mothers and fathers answered the same questionnaires.

As you'd expect, all the non-cognitive factors were associated with the children's dental fear. So having a bad experience, having a more fearful temperament and having fearful parents were all associated with being more scared of the dentist. But none of these were as strongly related to the children's fear as their cognitive vulnerability, which explained an additional 20 per cent of variation in fear levels.

Particularly striking was the finding that a bad experience was no longer associated with children's dental fear once cognitive vulnerability was taken into account. The implication is that a bad experience only leads children to fear the dentist if it increases their feelings of uncontrollability, dangerousness and so forth. Of the various components of children's cognitive vulnerability, it was perceived disgustingness that was most strongly related to their fear of the dentist.

Another finding was an association between children's cognitive vulnerability and their parents' cognitive vulnerability. Although there's no proof here that the parents are passing their thinking style onto their children, the researchers said this could reflect a kind of "cognitive transfer" among family members. This suggests that interventions aimed at reassuring children may need to target parents too.

Some further curiosities - the dental fear of children younger than 13 was more closely associated with their father's fear; for teenagers over 13, their fear was tied more with their mother's fear. Overall, cognitive vulnerability was more strongly associated with dental fear in teenagers, perhaps because of their increasingly mature thought processes.

Crego and his colleagues said their "cognitive approach may help explain why some children develop dental fear problems after suffering a negative dental experience and how dental anxiety is passed from parents to children."

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Crego, A., Carrillo-Diaz, M., Armfield, J., and Romero, M. (2013). Applying the Cognitive Vulnerability Model to the analysis of cognitive and family influences on children's dental fear. European Journal of Oral Sciences DOI: 10.1111/eos.12041

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

"It's about accepting that you're mortal" - Extreme sports enthusiasts on overcoming fear

In a safety-obsessed culture, why do some people throw caution to the wind and pursue sports where a wrong move often means instant death? Clues come from a series of interviews conducted with a group of 15 extreme sport participants (aged 30 to 70; 10 men) about their relationship with fear, including BASE jumpers (who launch themselves off high buildings), big wave surfers and waterfall kayakers.

Eric Brymer and Robert Schweitzer transcribed the interviews and looked for emerging themes. Contrary to traditional accounts of extreme sports enthusiasts as thrill seekers with a death wish, the interviewees described fear as an aversive, bodily sensation that the rest of us can recognise. A "gut-wrenching, terrible experience" was how one BASE jumper put it. "If you want a true slogan for these sports," he added, "it is Oh please don't let me die!". However, the interviewees also described how they face their fears and "push past" them.

Also contrary to some of the "devil may care" stereotypes that have dominated scientific and media portrayals of this group, the interviewees spoke of the importance of fear as a "healthy emotion" that "keeps you alive". Indeed, another of the themes related to "managing fear", with several participants describing their "fascination" with controlling their fear so as to avoid panic. "Fear is both a primal emotion and an experience to be savoured, confronted or broken through" the researchers said, "rather than as a stimulus for retreat."

The last theme on "self-transformation" was the most intriguing. The participants described how experiencing, controlling and pushing past intense fear left them positively changed and better equipped to deal with the tribulations of everyday life. A mountain climber described dealing with fear as "empowering" and "feeling very at peace" afterwards. A BASE jumper described the pursuit as "the ultimate metaphor for jumping into life rather than standing on the edge quivering". She also captured poetically the sense many of the interviewees had of becoming one with nature at the moment of most intense danger, as if "just a leaf in the wind: you're totally vulnerable and totally part of the environment at the same time. It's about accepting that you're mortal ... very vulnerable ... like a piece of dust ... in the wind." Another participant talked about a transformational "aura" that stayed with him "for as long as you care to remember."

According to Brymer and Schweitzer, these accounts "provide a critique of fear" as it is usually understood in conventional psychology, as always associated with dread. For the extreme sports enthusiast, fear is a useful emotion that aids survival but which ultimately can be transcended leading to personal growth and change. "By facing our greatest 'true' fears," said Brymer and Schweitzer "whether they be death, uncertainty or something else and taking action despite these fears, we transcend our own limitations and invite new possibilities into our lives."

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Brymer, E., and Schweitzer, R. (2013). Extreme sports are good for your health: A phenomenological understanding of fear and anxiety in extreme sport. Journal of Health Psychology, 18 (4), 477-487 DOI: 10.1177/1359105312446770

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

Why your friends on Twitter are (probably) more interesting than you, and what to do about it

Statistical logic means that your lover has probably had more sexual partners than you. Similarly, at the gym, most of the other users train more frequently than you. And your friends have more friends than you do - this last observation was labelled the "friendship paradox" by sociologist Scott Feld. It's a fact because popular people get counted in more people's tallies of how many friends their friends have (here's more explanation).

Now thanks to a new paper by Nathan Hodas and his colleagues, we can add to this humbling stats lesson the fact that for most users of Twitter, our followers and followees (the people we choose to follow), are better connected, more active, and more interesting than we are.

Hodas' team analysed Twitter data from the second half of 2009 featuring 476 million tweets and 5.8 million users, with 193.3 million links between them. First off, they found that for most of us, the people we choose to follow are better connected - that is, they typically follow ten times as many people as we do. Our followers too are better connected, typically by a factor of twenty.

Seeing as we choose how many other people we want to follow, this first observation isn't such a blow to the ego. However, the researchers found a similar result for popularity. That is, the people who follow us are typically ten times more popular than we are (in terms of their own follower count). Less surprising, the people we choose to follow are also more popular than we are. Here there are two distinct groupings - in one, the people we follow are typically ten times as popular as us; in the other, they are typically 10,000 times as popular (this is thanks to celebrity accounts and such like).

Not only are our followers and the people we follow better connected and more popular than we are, the people we follow are also usually more active. Eighty-eight per cent of users were found to be less active than a typical person they followed; this rose to 99 per cent when omitting accounts that ceased activity during the period covered by the data. This is probably because we're more likely to follow accounts that are more visible by virtue of being more active.

A related observation was the link between activity and popularity - that is, more active users tended to be more popular, a correlation the researchers described as "especially strong". This suggests being more active on Twitter could be a simple way to gain more popularity, although we need to be cautious because there's no proof here for a causal link. "The detailed mechanism for this explanation is not yet clear," the researchers admitted.

To connectivity, popularity and activity, we can add interestingness. The researchers looked at the "virality" of links shared on Twitter - literally how many times they were re-tweeted. Here they found that 79 per cent of Twitter users posted less viral content than the people they follow.

Another issue the researchers looked at was what they called "information overload". Here they found that as the number of people we follow increases, the information that we're subjected to increases "super-linearly" - each new user that we follow typically equals hundreds of new items of information in our Twitter stream. In part this is because, as we heard, the people we follow are usually highly active (or at least more active than we are). The risk is that we end up subscribing to more information than we can possibly manage to consume.

This last point about overload is relevant to readers hoping to boost their popularity and interestingness on Twitter.  Comparing overloaded Twitter users (the third receiving the most amounts of info), and the underloaded (the bottom third), Hodas and his colleagues found that the overloaded tended to receive information that had gone massively viral, but tended to overlook "mini-cascades" - information that had viral potential. "It appears that overloaded users are only good detectors for information of mid-range interestingness," the researchers said. "Most likely the information that their friends already know." This suggests that if you want to be the kind of user who helps to break the next big story on Twitter, you need to be careful not to follow too many accounts in the pursuit of this aim. Pick and choose who you follow with care.

"If you have ever felt like your friends are more interesting or more active than you are," the researchers concluded, "it seems the statistics confirm this to be true for the vast majority of us."

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Nathan O. Hodas, Farshad Kooti, and Kristina Lerman (2013). Friendship Paradox Redux: Your Friends Are More Interesting Than You. arXiv arXiv: 1304.3480v1

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