In the Exploratorium’s distorted room

The San Francisco Exploratorium is the Mind Hacks of science museums – every exhibit is hands on, giving you the chance to experiment with and experience for yourself scientific principles.

Obviously, one of my favourite exhibits was a psychology demonstration, one based on a classic visual illusion known as the “Ames’ Room”. We’ve a small model of this in Sheffield, which I use when teaching PSY101, but the Exploratorium’s “distorted room” is full size demonstration of the effect. Here’s me and a friend in the room:

Notice anything odd? We’re the same size in reality, but I (on the right) look significantly larger.

The illusion takes advantage of the unavoidable principle that size and distance are confounded – known as “Emmert’s Law“. It is Emmert’s Law that means that big things far away can look the same size as small things near by. Our brain makes assumptions about how far away things are and uses these to inform our impression of size. The distorted room is built so that, from one perspective only, the two sides of the room look an equal distance away. In fact, the corner on the right is far closer to the viewer (the camera in this case) than the corner on the left. Because I really am nearer the camera I make a larger image on the retina (take up more pixels on the camera), but because the brain assumes that I am the same distance away as my friend on the left the only conclusion that my visual system can draw is that I must be much larger than him.

Normally your visual system isn’t fooled about depth – clues in the scene, the difference between the image on your two eyes and movements of your head can all help reveal how far away different parts of the scene are. The distorted room removes some of these clues by forcing you took look at the room with one eye from a fixed point, and other clues it deliberately tricks (like the shape of tiles on the floor, which look the same from left to right, but actually get smaller, because the tiles on the right are closer).

The confounding of size and distance is the same principle behind illusions like this:

giantbottle.jpg

The effect only works because it is in a photograph (so from one perspective) and because the relatively featureless desert removes other clues to the depth of objects.

So the next time you close one eye and line up someone in the distance between your thumb and forefinger while muttering “I’m crushing your head!“, think of Emmert’s Law. And if you are in San Francisco, visit the Exploratorium!

How cannabis makes thoughts tumble

Cannabis smokers often report that when stoned, their thoughts have a free-wheeling quality and concepts seem connected in unusual and playful ways. A study just published online in Psychiatry Research suggests that this effect may be due to the drug causing ‘fast and loose’ patterns of spreading activity in memory, something known as ‘hyper-priming’.

Priming is a well studied effect in psychology where encountering one concept makes related concepts more easily accessible. For example, classic experiments show that if you see the word ‘bird’ you will react more quickly to words like ‘wing’ and ‘fly’ than words like ‘apple’ and ‘can’ because the former words are more closely related in meaning than the latter.

In fact, it has been shown that the more closely related the word, the quicker we react to it, demonstrating a kind of ‘mental distance’ between concepts. Think of it like dropping a stone into a pool of mental concepts. The ripples cause activity that reduces in strength as it moves away from the central idea.

‘Hyper-priming’ is an effect where priming happens for concepts at a much greater distance than normal. For example, the word ‘bird’ might speed up reaction times to the the word ‘aeroplane’. To return to our analogy, the ripples are much stronger and spread further than normal.

The effect has been reported, albeit inconsistently, in people with schizophrenia and some have suggested it might explain why affected people can sometimes make false or unlikely connections or have disjointed thoughts.

As cannabis has been linked to a slight increased risk for psychosis, and certainly causes smokers to have freewheeling thoughts, the researchers decided to test whether stoned participants would show the ‘hyper-priming’ effect.

The experiment used a classic ‘lexical decision task‘ where the volunteers are shown an initial word (‘time’) and then after a short gap are shown a nonsense word (‘yipt’) and a true word (‘date’) at the same time and have to indicate as quickly as possible which is the real world.

The experimenters altered how related the initial word and true word were to test for the semantic distance effect, and also varied the gap between the initial word and the test to see how long the priming effect might last.

Volunteers who were under the influence of cannabis showed a definite ‘hyper-priming’ tendency where distant concepts were reacted to more quickly. Interestingly, they also showed some of this tendency when straight and sober .

Cannabis also had the effect of causing temporary psychosis-like distortions as would be expected from a psychedelic drug, but the smokers did not make more errors and were not more likely to report psychosis-like symptoms when sober, suggesting the effect was not due to general mental impairment and couldn’t be explained by underlying tendency to mental distortion.

Although the debate is not completely settled, there is now good evidence that cannabis causes a small increased risk for developing schizophrenia particularly when smokers start young. In fact, additional evidence on this front was published only this week.

The researchers discuss the possibility that long-term smokers who spend a lot of time in a chronic ‘hyper-primed’ state might make psychosis more likely by loosening the boundaries of well-grounded thought, although exactly how cannabis raises the risk of psychosis, and indeed, how exactly it affects the brain, is still not understood well-enough to make a firm judgement.

Link to PubMed entry for cannabis ‘hyper-priming’ study.

Tracking the unborn brain into childhood

A brain scanning technology called MEG is being used to track the function of unborn babies’ brains as they grow inside the womb until after they’ve been born.

The full name for MEG is magnetoencephalography and it works by reading the magnetic fields created by the electrical signalling in the brain.

One of the advantages is that it can be used at various angles, doesn’t require the person to be in a cramped space, and is less sensitive to movement, so is ideally suited to scanning babies.

This includes unborn babies and with a bit of modification, as illustrated in the picture, researchers can pick up signals from the fetal brain in response to flashes or light or sounds.

We discussed the use of fMRI to scan the fetal brain previously, but this is a remarkable study that scanned the brains of babies inside the womb, every two weeks from week 27 until delivery, and then once after they were born.

Clearly, unborn babies are not the best at doing tasks set by experimenters, but there are various tests that just require the individual to experience changes in what’s presented to them.

One is called the auditory oddball task, where a series of tones are played that can either be similar (‘beep beep beep’) or can have include an ‘oddball’ (‘beep beep boop’). The brain is very good at picking out differences and the oddball is known to reliably trigger brain signals related to detecting changes.

This was the exact task used with the babies and the researchers looked to see if they could pick out a brain reaction to the ‘oddball’.

They found that they could detect this response 83% of the time in unborn babies, and that the reaction to the ‘oddball’ increased in speed throughout pregnancy. The newly born babies showed the response every time without fail.

This is an impressive finding as it shows how the brain development of the unborn child can be tracked over time with a brain scanner.

In a recent review article that discusses the development of this technology, the same group of researchers suggest that these and similar techniques could help track how different conditions in the mother affect the developing brain and even how the brain begins to develop its understanding of speech sounds before birth.

Link to PubMed entry for MEG study of developing fetus.
Link to PubMed entry for review article on fetal MEG.

A man with virtually no serotonin or dopamine

Neuroskeptic covers a fascinating case of a man born with a genetic mutation meaning he had a severe lifelong deficiency of both serotonin and dopamine.

The case report concerns a gentleman with sepiapterin reductase deficiency, a genetic condition which prevents the production of the enzyme sepiapterin reductase which is essential in the synthesis of both dopamine and serotonin.

The most widely recognised symptoms of the condition, linked to the deficiency in dopamine which has an important role in controlling movement, are problems coordinating both conscious movements and the unconscious control of muscles that allows simple actions. Unconscious control requires that the brain signals one muscle to contract while releasing the complementary muscle, and problems with this process cause spasticity.

The effects the condition on serotonin, often stereotyped as the ‘happy chemical’, are less well known, but in this case it was clear that the patient wasn’t depressed but did some other difficulties:

These included increased appetite – he ate constantly, and was moderately obese – mild cognitive impairment, and disrupted sleep:

“The patient reported sleep problems since childhood. He would sleep 1 or 2 times every day since childhood and was awake during more than 2 hours most nights since adolescence. At the time of the first interview, the night sleep was irregular with a sleep onset at 22:00 and offset between 02:00 and 03:00. He often needed 1 or 2 spontaneous, long (2- to 5-h) naps during the daytime.”

After doctors did a genetic test and diagnosed SRD, they treated him with 5HTP, a precursor to serotonin. The patient’s sleep cycle immediately normalized, his appetite was reduced and his concentration and cognitive function improved (although that may have been because he was less tired)…

Overall, though, the biggest finding here was a non-finding: this patient wasn’t depressed, despite having much reduced serotonin levels. This is further evidence that serotonin isn’t the “happy chemical” in any simple sense.

This is another piece of evidence against the common myth that depression is “caused by low serotonin” although Neuroskeptic speculates whether the link between disrupted sleep and depression may indicate an effect of serotonin dysfnction.

Link to Neuroskeptic on ‘Life Without Serotonin’.
Link to summary of scientific paper.

The disembodied tic

Photo by Flickr user EugeniusD80. Click for sourceThere are numerous forms of body distortions and out-of-body experiences reported in the neurological literature but this is the first case I’ve found of someone who experienced tics that seemed to occur in external objects.

The report was published in the journal Neurology in 1997 and concerns a man with Tourette’s syndrome, a condition of persistent tics.

These more commonly appear as almost irresistible repetitive movements that the person feels compelled to complete, but occasionally they can appear as what are known as ‘sensory tics’ which are repetitive sensations such as feelings of pressure, tickle, warmth, cold, or other abnormal sensation in skin, bones, muscles, and joints.

In this case, however, the sensations felt as if they were appearing in external objects:

A 34-year-old man dated the onset of his symptoms to age 5 when he developed a compulsion to bite down on cups and glasses. The drive was so irresistible that he once shattered a glass in his mouth. He later began having painful repetitive neck extension and shoulder shrugging. During childhood, he first noticed itchy or pressure sensations, usually deep in a joint, but sometimes on the skin, in his hands, feet, and arms. The sensations eventually spread. For a period of time, the inside of his knees and ankles were particularly affected and the sensation could only be relieved by banging his ankles together. Noises including grunts, sniffs, and loud shouts began during early adolescence. A period of coprolalia was present briefly. The tics came to involve the entire body. He had associated difficulty concentrating, compulsions, and obsessions. He was given a trial of clonidine without relief. He was never tried on other medications.

The patient characterizes his motor tics as voluntary movements performed in response to the “itchy” feeling. Although he can partially suppress tics in any given location, suppression enhances the feeling that he must move another body area. He frequently has the urge to repeat what others say to him but can usually suppress it. Beginning during childhood and persisting through adulthood, the patient noticed that the itchy sensations preceding motor tics could arise in other people or in objects.

The extracorporeal sensations are associated with the need to scratch or touch the itchy item in a particular way. External sensations most frequently arise in angles, corners, and points of objects such as elbows, the edges of tables, or the edge of his computer screen. Out-of-body sensations are more likely if the patient is touching an object but can also arise without direct contact. When younger, the patient would act on the accompanying urge and would scratch his sister’s elbow. He is able to resist touching other people.

Disembodied sensations are not uncommon after neurological difficulties (for example, a recent case study of a person with epilepsy reported a feeling of complete disembodiment) and can even be induced in you and me, as the ‘rubber hand illusion‘ demonstrates.

In this case, however, it isn’t clear exactly how the Tourette’s syndrome is triggering the feeling that the sensations appear in other objects, although it does suggest that our self-other boundary is not as iron-clad as we sometimes like to believe.

Link to PubMed entry for case study.

Go Cognitive guide to the brain

Go Cognitive is an awesome free video archive of interviews and discussion that aims to explain some of the core topics in cognitive neuroscience.

It’s a project of the University of Idaho who’ve managed to convince some of the leaders in the science of the brain to talk about their work.

There are videos on fMRI, neuroplasticity, attention and neurological problems to name but a few, and there’s even a talk on psychology and stage magic.

The website also has a demo section that demonstrates some of the principles in action.

My only complaint is that you can’t download the videos, they can only be streamed, but nevertheless they remain a fantastically produced high quality series. Bravo.

Link to Go Cognitive videos (thanks Peter!).

Future neuro-cognitive warfare

Every year the US Army holds an annual conference called the “Mad Scientist Future Technology Seminar” that considers blue sky ideas for the future of warfare. Wired’s Danger Room discusses the conference and links to an unclassified pdf summary of the meeting which contains this interesting paragraph about ‘neuro-cognitive warfare’:

In the far term, beyond 2030, developments in neuro-cognitive warfare could have significant impacts. Neuro-cognitive warfare is the mashing of electromagnetic, infrasonic, and light technologies to target human neural and physiological systems. Weaponized capabilities at the tactical level will be focused on degrading the cognitive, physiological, and behavioral characteristics of Soldiers. Its small size and localized effects will make it ideal for employment in urban areas. Such technology could be employed through online immersive environments such as 2d Life or other electronic mediums to surreptitiously impact behavior without the knowledge of the target.

I presume ‘2d Life’ refers to Second Life, but I could be wrong.

The first part is discussing the conventional development of warfare technology designed to target the nervous system, which is a long-established military tradition that has included weapons such as the rock, the poison-tipped arrow, the nerve gas shell and a new generation of hush-hush electromagnetic weapons.

The second part is a little more interesting, however, it implies that a certain form of stimulation embeddable in a popular game or internet service (I think they’re too shy too to say porn) might reduce cognitive performance by only a fraction, but when considered over a whole army, it could make a difference to the overall fighting force.

The scenario is a little bit science fiction (Snow Crash anyone?) but is an intriguing possibility given that only a slight change would be needed in an individual to justify its effect if it could be distributed over a wide enough population.

For example, many priming studies have shown it is possible to influence behaviour just by exposing people to certain concepts.

In one of my favourite studies, exposing people to ideas about elderly people slowed their walking speed, while a more recent experiment found this effect could change action sequences as well.

Link to Danger Room coverage of ‘Mad Scientist Seminar’.
pdf of unclassified military summary.

In the blood

Wikipedia has a page on the idea that blood type predicts personality, a discredited theory that nevertheless remains widespread in Japanese and Korean popular culture.

The idea seems to hold a similar cultural position as star signs and astrology and is used as a platform for discussing relationship compatibility and vague personality characteristics.

This is from a 1998 article from the Journal of Cross Cultural Psychology:

For example, in Southeast Asia, one can find many ideas about personality ranging from typologies based on blood types, horoscopes and fortune telling of various kinds, to personality theories similar to the “Big Five“. For example, since World War II, it has been popular in both Japan and Korea to classify people according to their blood types and elaborate theories of the qualities and characteristics of people with type A, B, AB, or O blood. Type A people, for instance, are considered to be serious and ordinary and type Bs to be unique and “going my own way.” Young Japanese commonly exchange this information about themselves and make predictions about the course of their relationships based on this information.

The Wikipedia notes that many Japanese video games often list the blood types of the characters, presumably to reflect their presumed personality.

Link to Wikipedia page on blood type and personality beliefs.
Link to summary of cross cultural personality article.

2010-03-05 Spike activity

Quick links from the past week in mind and brain news:

Time magazine reports on how darkness can encourage dishonest acts even when anonymity is accounted for.

A study finding a link with aversion to inequality an activity in the ventral striatum is brilliantly covered by The Frontal Cortex.

The Point of Inquiry podcast has an excellent discussion on the psychology of cold reading.

A preview of a special journal issue on ‘Neuroscience, power and culture’ is covered by Advances in the History of Psychology.

The Globe and Mail covers a study finding that children highly sensitive to stress can excel given the right support and environment.

Nobel-prize winning psychologist Daniel Kahneman discusses judging happiness and the paradox of experience vs memory in a talk for TED.

Neurophilosophy covers two new studies finding that face recognition ability is partly inherited.

“As for the effectiveness of gay conversion, Core’s Dr Davidson acknowledges that there are ‘relapses'”. Damn those Speedos. The Irish Independent has an article on gay conversion therapy in Ireland.

The Neurocritic has a thoughtful response to the recent NYT article on the possible cognitive benefits of depression.

‘Ministrokes‘ may cause more damage than thought, according to research covered by Science News.

The Neuroskeptic has an excellent piece on the decline and fall of the cannabinoid antagonists, a class of drug supposed to be the next big thing in treating obesity.

Research finding that as pornography has increased in availability, sex crimes have either decreased or not increased in every region investigated is discussed in The Scientist.

Dr Petra looks at the background to the recent report on sexualisation and young people from the UK government with more analysis to follow. After reading the report, I can’t help but suggesting someone point out the difference between correlation and causation to its author.

A hay fever medicine that showed early promise as a treatment for Alzheimer’s disease does nothing to stave off dementia, a large clinical trial concludes. Coverage from the New Scientist blog.

The Philosopher’s Zone programme from ABC Radio National has a good discussion on perception, sensation and consciousness with Nicholas Humphrey.

There’s a video profile of an ex-narc who catches bent cops framing people for drugs offences over at Boing Boing.

New Scientist discusses whether brain scans could gives us an objective measure of the intensity of pain.

The excellent Addiction Inbox blog contrasts how the media covers harm reduction services (‘they promote drug abuse’) and what the scientific studies say (the opposite).

io9 discusses research finding that oxygenated booze gives you less of a hangover. No word on how it affects the beer goggles effect.

UK may end its controversial “dangerous and severe personality disorder” program, according to excellent In The News.

Current Biology has a freely accessible paper on ‘archaeogenetics‘ – the use of genetics to understand human history.

Eric Barker’s Barking Up the Wrong Tree blog is full of fascinating and off-beat psychology snippets.

Mental Nurse blog has a funny post classifying types of annoying psychologists, occupational therapists and the like in mental health.

There’s a video interview with neurophilosophers Pat and Paul Churchland over at The Science Network.

Women with hour-glass figures activate the neural reward centre of the male brain, according to a study covered by the BPS Research Digest. Women with eye-glasses, even better.

BBC News discusses the cult of Omega-3 and why your life’s problems will not be solved by fish oil, despite that the advertisers will tell you.

The Coney Island Amateur Psychoanalytic Society Dream Films 1926-1972.

When they were drunk, bigger men became especially aggressive when given the opportunity to administer electric shocks to a fictitious opponent in a laboratory contest, according to research covered by Science News

Neuroanthropology links to videos from The Encultured Brain conference which are now available online.

“Only occasionally do studies come out that improve the image of men as more than stubborn, violent and incorrigible beasts with malfunctioning moral compasses. The study I‚Äôm about to talk about isn‚Äôt one of them.” Neuronarrative on a study of male and female guilt.

The Research Blogging Awards finalists have been announced and there’s much mind and brain goodness inside. I had the pleasure of judging the the English and Spanish language entries.

How reliable are fMRI results?

A new study has looked at the reliability of fMRI brain scanning results over time, finding that the same experiment will only only be moderately reproducible when conducted at two different times, suggesting that fMRI is much less reliable than most researchers assume.

The authors of the paper are the same ones who brought us the study showing that it’s possible to find ‘brain activity’ in a dead fish if the analysis is done in a way that is common but prone to false positives.

The paper will shortly appear in the Annals of the New York Academy of Sciences but they’ve put a copy online and, although it’s a scientific article, it’s remarkably easy to read.

They review all the studies to date on what is known as the ‘test-retest reliability‘ of fMRI. This refers to the ability of a measure to give reproducible results.

For example, if you’re measuring an adult’s height you want to make sure that your tape measure gives you similar results each time you use it on the same person. Of course, you may have readings that vary by a millimetre or two each time, but if you get wildly different results on Monday and Tuesday, you probably want to bin your tape measure.

In fMRI there are two types of results. One is ‘where in the brain’ and the other is ‘how strong’ is the activity.

We can examine the first by looking at how well the active brain areas overlap in scans taken at two different times, and we can examine the second by looking at the similarity of the strength of the results using a statistical test like a correlation.

The better the overlap and the statistical relationship between the results from the same test on the same people at different times, the more we can rely on our measurement technique.

This new analysis reviewed all the previous studies that have looked at the test-retest reliability of fMRI and found that overall, active brain areas overlap about 30% of the time and the correlation for the strength of the activity was about 0.5. To get some perspective a result of 1 would indicate perfectly reliable and reproducible results while a result of 0 would indicate no reliability at all.

An overlap of 30% and a correlation result of 0.5 shows fMRI has moderate reliability, but is much poorer than most people assume.

However, this overall result is perhaps a little too broad, and the authors make the point that the reliability varies depending on the type of scanner being used, what test is being carried out by the participants, what brain areas are being investigated and how the results are analysed.

Indeed, a recent study on the test-retest reliability of fMRI studies of the ‘reward system’ found the reproducibility of the results to be worse than this general figure while another study found an auditory detection task produced better results.

The authors conclude:

One thing is abundantly clear: fMRI is an effective research tool that has opened broad new horizons of investigation to scientists around the world. However, the results from fMRI research may be somewhat less reliable than many researchers implicitly believe. While it may be frustrating to know that fMRI results are not perfectly replicable, it is beneficial to take a longer-term view regarding the scientific impact of these studies. In neuroimaging, as in other scientific fields, errors will be made and some results will not replicate. Still, over time some measure of truth will accrue. This chapter is not intended to be an accusation against fMRI as a method. Quite the contrary, it is meant to increase the understanding of how much each fMRI result can contribute to scientific knowledge.

Link to full text of paper (via @hysell).

In Our Time on the Infant Brain

This morning’s edition of BBC Radio 4’s brilliant In Our Time was dedicated to the infant brain and has a wide ranging discussion about how ideas about the early development of the child developed into the modern age of neuroscience.

The streamed version will be available on the website permanently, but if you want to download the podcast you only have a week to do so from this page.

Melvyn Bragg and guests Usha Goswami, Annette Karmiloff-Smith and Denis Mareschal discuss what new research reveals about the infant brain.

For obvious reasons, what happens in the minds of very young, pre-verbal children is elusive. But over the last century, the psychology of early childhood has become a major subject of study.

Some scientists and researchers have argued that children develop skills only gradually, others that many of our mental attributes are innate.

Sigmund Freud concluded that infants didn’t differentiate themselves from their environment.

The pioneering Swiss child psychologist Jean Piaget thought babies’ perception of the world began as a ‘blooming, buzzing confusion’ of colour, light and sound, before they developed a more sophisticated worldview, first through the senses and later through symbol.

More recent scholars such as the leading American theoretical linguist Noam Chomsky have argued that the fundamentals of language are there from birth. Chomsky has famously argued that all humans have an innate, universally applicable grammar.

Over the last ten to twenty years, new research has shed fresh light on important aspects of the infant brain which have long been shrouded in mystery or mired in dispute, from the way we start to learn to speak to the earliest understanding that other people have their own minds.

Link to In Our Time ‘The Infant Brain’ (thanks Petra!)

Cocaine, surgery and an experiment too far

William Stewart Halsted is known as the ‘father of American surgery’ and was widely-known to have been addicted to both cocaine and morphine for large stretches of his life. I always assumed this was due to recreational sampling of the medicine cabinet but it turns out it was the rather unfortunate result of some initially serious scientific experimentation.

I just found this article on Halsted from The Annals of Surgery that explains the astounding and tragic story.

Halsted’s career changed dramatically on October 11, 1884, when he read in the Medical Record a report of the Ophthalmological Congress in Heidelberg. Dr. Henry D. Noyes, who had attended the conference, reported that the most notable event at the Congress was a demonstration of the extraordinary anesthetic power that a 2% solution of muriate of cocaine had on the cornea and conjunctiva when it was dropped into the eye. Later in his report, he was prophetic in his summary that “it remains, however, to investigate all the characteristics of this substance, and we may yet find that there is a shadow side as well as a brilliant side in the discovery.”

After reading this report, Halsted quickly obtained cocaine and began a series of experiments on himself, colleagues, and medical students that led to the development of local and regional anesthesia. Through a series of brilliant experiments, Halsted showed that virtually every peripheral nerve in the body could be injected with cocaine so that its peripheral distribution was anesthetized entirely and thus rendered insensitive to surgical interventions. This, of course, was of particular interest to dentists, and in 1922, shortly before his death, his priority in being the first to show the anesthetic properties possible with local infiltration of nerves was established by the National Dental Association. Unfortunately, during the process of these experiments, Halsted and several of his colleagues became addicted to cocaine. Only Halsted and Dr. Richard Hall, who moved subsequently to Santa Barbara, California, for his rehabilitation, survived. The rest died of their addiction.

Halsted’s only publication on local and regional anesthesia appeared in the New York Medical Journal in 1885. This article is a rambling, incoherent paper that is a testament to the addicted debilitated state that Halsted had reached. The first sentence of that article reads as follows: “Neither indifferent as to which of how many possibilities may best explain, nor yet at a loss to comprehend, why surgeons have, and that so many, quite without discredit, could have exhibited scarcely any interest in what, as a local anesthetic, had been supposed, if not declared, by most so very sure to prove, especially to them, attractive, still I do not think that this circumstance, or some sense of obligation to rescue fragmentary reputation for surgeons rather than the belief that an opportunity existed for assisting others to an appreciable extent, induced induced me, several months ago, to write on the subject in hand the greater part of a somewhat comprehensible paper, which poor health disinclined me to complete.”

Link to PubMed entry for article.
Link to full text at PubMed central.

All aboard the baby brain

The March edition of The Psychologist has just appeared online and has two freely available articles: one article investigates whether women really suffer a reduction in mental sharpness during pregnancy, and another interviews baby psychologist Alison Gopnik about her work.

This idea that pregnancy causes a slight reduction in mental sharpness, sometimes known as ‘baby brain’ or ‘pregnesia’, is widespread but the results from scientific studies are mixed, and at best show only a negligible effect:

We’ve seen that whilst many women report experiencing cognitive difficulties during pregnancy, objective evidence for a link between pregnancy and cognitive decline has been inconsistent. This begs the question: does the memory deficit, if it exists, matter? Is there sufficient cause for women to worry about it? On the other hand, if there is no deficit, should we be doing more to combat what amounts to a pervasive sexist myth?

Crawley says that even if there is a real deficit, it’s nothing to worry about. ‘In a previous study of mine, before I gave women the standard questionnaire comparing their cognition now to before they were pregnant, I asked them to tell me about the kinds of changes they’d noticed about themselves since they’d become pregnant. Out of 198 women, only three spontaneously mentioned cognitive changes, so I don’t think they’re very salient.’

The interview with Alison Gopnik, is, as always, thoroughly engaging and largely riffs on themes from her new book The Philosophical Baby.

Link to Psychologist article ‘The Maternal Brain’.
Link to interview with Alison Gopnik.

Full disclosure: I’m an unpaid associate editor and occasional columnist for The Psychologist and I worked as a baby early in my career.

Tipsy thinking

Photo by Flickr user rpeschetz. Click for sourceSeed Magazine has a great short article on misperceptions and counter-intuitive findings concerning alcohol and drinking.

The piece covers whether alcohol break-down product acetaldehyde plays as much a part in drunkenness as alcohol itself, misperceptions about the chances of women having their drink spiked to facilitate sexual assault, and mothers’ perceptions about their kids future drinking patterns.

Alcohol is so embedded in most cultures that perceptions and reality intermix in surprising ways. Last week psychologist Polly Palumbo discussed a 2008 study about mothers’ beliefs about their own kids’ drinking. You might think that if mothers were concerned about their young children becoming drinkers in high school, they might be more successful in preventing some of the kids from actually engaging in underage drinking. In fact, the study, led by Stephanie Madon and published in the Journal of Personality and Social Psychology, found the opposite. Mothers who worried their children might become drinkers had kids that were significantly more likely to drink.

The researchers are careful to point out that the study is just a correlation; we can’t say that the mothers’ belief about drinking is what caused their kids to drink. But because the study was administered over several years, it’s better than many correlational studies: We know the belief preceded the drinking, so it’s pretty much impossible that the kids’ drinking behavior itself led to the belief.

Link to Seed article ‘A Sober Assessment’.

Violent video games: small causal link with aggression

A new study just published in Psychological Bulletin has reviewed studies on the effects of violent video games and concludes that they cause a small but reliable increase in aggressive behaviour and anti-social thinking.

The study, led by psychologist Craig Anderson, is a type of meta-analysis which attempts to mathematically aggregate the results of past studies to see what the overall effect is.

There have been several similar studies in recent years which have come to different conclusions, based on whether the results have been thought to have been affected by publication bias or not. In other words, while the published studies suggest there is a small reliable effect of video games on aggression some reviews have suggested this is because fewer of the studies that don’t find a link actually get published.

This new study aimed to include unpublished studies and also looked at studies from both Western cultures, like the US and Europe, and Eastern cultures, such as Japan, to see if social environment influences any potential link.

The review included both observational studies, which look at what happens in the ‘real world’ but can’t tell us whether gaming causes aggression (it could be just that more aggressive people play more violent games), and experimental studies which can determine cause, because participants are randomly assigned to groups and given either violent or non-violent games, but are a little more removed from everyday life.

The researchers examined whether violent video games led to changes in aggressive behaviour, thoughts and emotions, and for changes in empathy and helpful behaviour to others.

Overall, the analysis concluded that violent video gaming causes a small but reliable increase in aggression and possibly a reduction in helpful behaviour and empathy.

The results on empathy were the weakest, however, as only study was an experiment and the researchers lumped together research that used questionnaires and which tested bodily desensitisation (whether people bodily react less to emotional events when they re-experience them) which is not a good measure of someone’s mental state.

One interesting aspect of the analysis is that the researchers looked at a number of game characteristics to see if they had an effect; for example, whether the people were playing in first- or third-person, whether the violence was towards human or non-human characters; and found that none of this made much difference.

What this suggests is that the effect is not due to non-specific priming, a psychological effect whereby experiencing one type of concept makes closely related concepts and actions more accessible and more likely. In this case, the fictional violence is assumed to make aggressive thoughts and actions more easily triggered.

It must be said that the overall effect was quite small. For the statistically inclined, the correlation was r = .19 for all studies and r = .24 when they looked only at the most rigorous research. This means that violent video games accounted for between about 3.6% and 5.8% of the total change in aggressiveness.

Interestingly, despite the fact that Japan, for example, is more culturally adverse to aggression than Western countries, the effects seems to be equally as apparent on either side of the world.

The journal published a discussion based on the study, including a criticism by psychologists Christopher Ferguson and John Kilburn, who have published previous analyses suggesting that the violence effect is down to publication bias.

The discussion focusses on various technical issues which are well answered by the original authors, although perhaps the most significant points of disagreement focus on two areas.

The first is that this new analyses only focused on simple relations, and didn’t take into account whether other factors could be having an influence. For example, a previous study suggested that when pre-existing emotional, family and social problems are accounted for, the aggression increasing effects of video games disappears.

The second concerns how important this small effect is. On an individual level a small change may be undetectable amid the to-and-fro of everyday life, but at the level of the population it could conceivably increase the number of aggressive incidents, although these are often the hardest effects to track.

Link to PubMed entry for study.
pdf of full text.