vaughanbell

US military pours millions into ‘EEG telepathy’

I get the feeling that DARPA, the American military research agency, only ever select their research projects from sci-fi comics.

Wired reports that their latest multi-million dollar project is to create an EEG-based ‘telepathy’ communication system for the battlefield solder:

Forget the battlefield radios, the combat PDAs or even infantry hand signals. When the soldiers of the future want to communicate, they‚Äôll read each other‚Äôs minds.

At least, that‚Äôs the hope of researchers at the Pentagon‚Äôs mad-science division Darpa. The agency‚Äôs budget for the next fiscal year includes $4 million to start up a program called Silent Talk. The goal is to ‚Äúallow user-to-user communication on the battlefield without the use of vocalized speech through analysis of neural signals.‚Äù That‚Äôs on top of the $4 million the Army handed out last year to the University of California to investigate the potential for computer-mediated telepathy.

Before being vocalized, speech exists as word-specific neural signals in the mind. Darpa wants to develop technology that would detect these signals of ‚Äúpre-speech,‚Äù analyze them, and then transmit the statement to an intended interlocutor. Darpa plans to use EEG to read the brain waves. It‚Äôs a technique they‚Äôre also testing in a project to devise mind-reading binoculars that alert soldiers to threats faster the conscious mind can process them.

It’s all getting a bit Rogue Trooper isn’t it?

Link to Wired on DARPA barmyness.

Visual Illusion Contest 2009 winners

The results of the annual visual illusion contest have just been announced and the 2009 winner is a doozy.

Like all the best visual illusions it’s conceptually simple but perceptually striking. In this case a falling ball seems to drop vertically when you look straight at it but seems to glide away at an angle when you see it in your peripheral vision.

Rather nicely, you can switch between the two effects just by looking back and forth. Make sure you click on the ‘Reversal’ button as well for a free-wheeling alternative version.

Visual illusions: the scooby snacks of perceptual psychology.

Link to Visual Illusion Contest website (via @mocost).

The Dark End of the Street

I’ve just found Steven Okazaki’s 1999 documentary Black Tar Heroin: The Dark End of the Street on YouTube that follows the chaotic lives of heroin addicts in Southern California.

It’s not polemic and tries as much as possible to simply document, but it’s a dark journey into the void with many of the people involved in the 1990s heroin scene.

It’s not easy to watch, but it is a rare insight into the lives of people who are often hidden in plain sight.

Link to Part 1 (links to other parts on right).

British twins in emotional sex shocker

If you’re all aflutter over the recent news reports that ’emotionally intelligent women have more orgasms’ you may be interested to know that these sexual adventures have been exaggerated in the re-telling.

I really recommend Petra Boyton’s analysis of the study which picks up on what was actually done and where its drawbacks were. As it turns out it was a postal survey of over 2,000 female twins, with a fairly low response rate and not particularly well-pitched questions on sexual experiences.

It also included an emotional intelligence measure, and found a small but statistically reliable link between ‘EQ’ and orgasm frequency during masturbation and sex.

And this is where it gets a bit over-the-top. The authors suggest, rather cautiously in the research article and, rather more strongly in the press reports, that higher emotional intelligence may help women communicate what they want in the bedroom and hence lead to more orgasms.

I shall now present the correlations between EQ and orgasm frequency as reported in the study:

EQ and frequency of orgasm during intercourse 0.13
EQ and frequency of orgasm during masturbation 0.23

If you’re familiar with how to read correlations, you’ll notice that the link is very small.

The correlation was done using a Spearman correlation that ranks everyone by EQ and then ranks everyone by orgasm frequency, and then sees how the rankings match.

A result of 1 mean the rankings are identical, a result of -1 means that one ranking is in exactly the opposite order to the other, and a result of 0 means there is no link at all between the two rankings. So in this case, the relationship is very minor.

And here’s a neat trick you can do with the results of correlations. If you square them, you get the amount of variability or change in one value accounted for by change in the other as a percentage.

This means EQ accounts for 1.7% of self-estimated intercourse orgasm frequency and 5.3% of self-estimated masturbation orgasm frequency.

It’s also worth noting that the relationship is stronger for masturbation than orgasm during intercourse, which kinda pours cold water on the ‘asking for what you want in bed’ angle.

Interesting, these results are statistically reliable, and the small but reliable effect was confirmed by a regression analysis, meaning that they are reasonably unlikely to have occurred by chance.

As Petra notes, it’s an interesting preliminary study that merits further investigation, but even if we could be completely confident in the methods, the effect is nothing to shout about.

Link to Dr Petra on ‘Do high EQ women have better sex?’
Link to study.
Link to DOI entry for same.

The study of a lifetime

It is not often that articles on psychology studies are described as beautiful, but a piece in The Atlantic on the Harvard Study of Adult Development is quite sublime.

The project has followed two groups of men for almost seventy years, tracking physical and emotional health, opinions and attitudes, successes and failures, all in the hope of understanding what makes us happy.

It weaves the staccato train of numerical data with reflections and insights from the men themselves to attempt the impossible – it hopes to record lives.

From their brash early adulthood to their deaths or dotage the stories are brief but profound, sometimes tragic, sometimes joyful, sometimes mundane.

The study itself has generated some remarkable findings, such as the massive impact of relationships, the fading long-term effects of childhood experiences, or the role of defences in managing emotional well-being, but the piece is as much about the life of the project as its conclusions.

It serves as a meditation on the tension between meaning and measurement when trying to understand the individual, and on the potentially futile attempt to extrapolate an experience of a generation to a world of other times, people and places.

But the article also about psychiatrist George Valliant, who has been coordinating the study for over 40 years, and whose life is intricately woven into the project.

The ending of the article is both surprising and poignant, because it questions what we can truly learn from the lives of others.

Link to Atlantic article ‘What Makes Us Happy?’

Delayed gratification and the science of self-control

The New Yorker has a fantastic article on the psychology of delayed gratification and how tempting kids with marshmallows allowed us to understand the life-time impact of self-control.

The piece focuses on the work of psychologist Walter Mischel who invented a test for children where they’d be presented with a marshmallow but told they could have two, later on, if they just waited.

It was an early demonstration of the power of temporal discounting – some kids ate the marshmallow, about a third waited and cashed in their patience for bigger rewards – but this wasn’t, in itself, particularly earth-shattering news.

What was most surprising was that years later, when Mischel followed up the kids in his experiment, the ones who waited, who could delay their gratification, turned out to be more successful in life – better jobs, better exam results, less drug addiction and so on.

This and subsequent research has led us to believe that the ability to delay gratification for better rewards in the future is a fundamental skill in success, probably because it looks at how emotions and motivations interact with a more rational appproach to reasoning. We know what’s best, but can we keep temptation at bay to reach it?

The article is a compelling exploration of this key ability and the subsequent research that has sprung up around it to help explain how we manage to keep those cheap instant hits at bay.

There’s also a great observation in the piece where the author, science writer Jonah Lehrer, describes Mischel as someone who “talks with a Brooklyn bluster and he tends to act out his sentences”.

Link to New Yorker article ‘Don‚Äôt! The secret of self-control’.

The alien hand syndrome – caught on video

I’ve just found a video of someone with alien hand syndrome – a condition which usually occurs after brain injury or stroke where the affected person loses conscious control over the hand and where it seems to move with a will of its own.

In this case, the video was uploaded by YouTube user frankenerin, who asked someone to video her when she was in intensive care after suffering a stroke and having brain surgery while her ‘alien hand’ was still present.

There’s a couple of things to notice in the video. The first is that the clinician asks the patient to do the actions for using scissors and brushing teeth. This is to check the problem is not a form of general ideomotor apraxia, where common action patterns are damaged.

She can do the actions with one hand but not the other, suggesting her strange movements are not due to global action planning problems.

The clinician then asks whether the patient recognises the arm as hers.

This may seem an odd question, but he’s checking for somatoparaphrenia, where patients can deny ownership of a paralysed or action-impaired limb, sometimes saying that it belongs to someone else.

As it turns out, the patient says she generally knows it is hers, but when it is draped across her body in a certain position and making involuntary movements she can think it is someone else’s limb. In other words, she seems to have fleeting somatoparaphrenia.

The video then shows the hand moving of its own accord and the patient having to use the other hand to keep it out of trouble.

Despite looking like she’s in pretty bad shape, frankenerin later posted a wonderful follow-up video where she is back on her feet and feeling fine, although discusses how she’s had to adjust her career aspirations owing to the longer-term effects of the brain injury.

Unfortunately, the Wikipedia page on alien hand syndrome, also known as anarchic hand syndrome, is dreadful, but there’s an excellent 2005 article from The Psychologist by neuropsychologist Sergio Della Sala that covers the neuropsychology of the condition and what it tells us about free will. You can read it online as a pdf.

Link to alien hand syndrome video.
pdf of The Psychologist on alien / anarchic hand.

Encephalon 70 the mysterious

The 70th edition of the Encephalon psychology and neuroscience writing carnival has just appeared and is ably hosted on Sharp Brains.

A couple of my favourites include a post on Neurotopia on the elegant logic of dopamine, and a fantastic visual illusion from Dr Deb where a picture of a tree hides some wonderfully concealed faces.

There’s a whole stack more great articles in this fortnight’s edition so go check out the rest.

Link to Encephalon 70.

Binge and tonic

There‚Äôs more to alcohol than getting pissed but you‚Äôd never know it from the papers. In a period of public hand wringing over ‚Äòbinge drinking culture‚Äô, our understanding of the ‚Äòculture bit‚Äô usually merits no more than an admission that people do it in groups and this is often implicit in the work of psychologists.

In a recent Psychological Bulletin review on the determinants of binge drinking, psychologists Kelly Courtney and John Polich devote only a few sparse paragraphs to the social issues in an otherwise impressive review, despite the fact that drinking alcohol is one of the most socially meaningful and richly symbolic activities in our culture.

In the UK at least, the social meaning of booze is often hidden behind the ordinariness of day-to-day consumption. If you can‚Äôt quite see past the barrier of banality, try buying one of your male colleagues a Babycham in public view and the symbolism of alcohol will quickly be made apparent.

But it is not just the meaning of drinks which determine the role alcohol plays in our lives, it is the meaning of drinking as well. Sociologists have been exploring this territory for years and we would do well to read their maps, because it shows us how culture influences not only our views on drunkenness, but the experience of being intoxicated itself.

In their classic 1969 book Drunken Comportment, MacAndrew and Edgerton compared alcohol use in cultures around the world, finding that what concerns us most today, drunken disorderliness, is not an inevitable result of getting pissed. A striking example was the Papago people of Mexico, who, during their traditional cactus-wine ceremonies, would imbibe so much as to become ‚Äúfalling-down drunk‚Äù.

Despite the large scale community boozing, the events were exclusively peaceful, harmonious and good tempered. Later, the availability of whisky brought with it the cultural connotations of European-style drinking, meaning it ‚Äòproduced‚Äô an aggressive, anti-social drunkenness, despite it being the same chemical in a different style.

Recent research on binge-drinking in Western youth has indicated that the negative effects, both personally toxic and anti-social, have been reframed as an adventure and bonding experience.

While health campaigns are focusing on risk reduction, research by Sheehan and Ridge with teenage girls in Australia found that any harm encountered along the way tends to be ‚Äúfiltered through a ‚Äògood story,‚Äô brimming with tales of fun, adventure, bonding, sex, gender transgressions, and relationships‚Äù.

Puking in the gutter has been turned into Sex and the City. Not the complete story, of course, but we neglect the culture of alcohol at the cost of failing to understand why binge drinking is in fashion.

This is one of the occasional columns I write for The Psychologist and the editor, Jon Sutton, has kindly agreed for them to be posted on Mind Hacks as long as I include the following text:

The Psychologist is sent free to all members of the British Psychological Society (you can join here), or you can subscribe as a non-member by emailing sarsta[at]bps.org.uk.

He’s also said that he might print particularly good or insightful comments in the magazine, after which fame and fine living will surely follow. If he’s interested in publishing your comment, he’ll contact you first to get permission.

Deeper into the neuroscience of hypnosis

A new article from Trends in Cognitive Sciences explores how cognitive neuroscientists are becoming increasingly interested in understanding hypnosis and are using it to simulate unusual states of consciousness in the lab.

Hypnosis was typically treated with suspicion by mainstream cognitive science, although an important turning point came when a 2000 study demonstrated that people hypnotised to see colour on grey panels showed activity in the colour perception areas of the brain.

Myths about hypnosis are still common, but it is nothing more than a participant’s willing engagement in a process of suggestion. The hypnotic induction, sterotypically the counting backwards and the ‘you are feeling sleepy’ patter, helps but is not necessary.

Crucially, and for reasons that are still unclear, we all vary in our hypnotisability. This characteristic is known to be more stable than IQ, and normally distributed, like many other psychological traits.

In other words, we can all experience the relaxation and focus, and we can all imagine what the ‘hypnotist’ is suggesting, but only more highly hypnotisable people experience the suggestions as involuntary, as if they’re happening ‘by themselves’.

Recent research has suggested that highly hypnotisable people can disengage the process that looks out for rival demands on our attention, from the process that allows us to focus on which of the competing tasks we need to home in on.

In other words, in highly hypnotisable people, suggestions to experience things contrary to everyday reality may be able to take effect because the normal detect and disentangle mechanism has been temporarily suspended.

Combined with carefully crafted suggestions, this ability allows researchers to simulate certain mental states and experiences in the lab.

For example, hypnotically suggested paralysis, blindness or loss of feeling have been used to simulate the symptoms of ‘hysteria’ or conversion disorder, a condition where neurological symptoms appear without any damage to the nervous system being present.

Other studies have used hypnosis to simulate the feeling that the body is being controlled by outside forces, a common symptom in psychosis, or where a patient thinks their reflection in the mirror is another person, a delusion called mirror misidentification.

And we covered a fantastic study last year, where researchers used hypnosis to simulated psychogenic amnesia, a loss of memory just for old information despite the fact that the patients have none of the brain damage associated with the classic amnesia syndrome.

This new in-depth article covers research attempting to understand hypnosis itself, and science that uses hypnosis as a lab tool, and is a great introduction to the neuroscience research in this developing area.

Link to article.
Link to DOI entry for same.

Full disclosure: the authors of the article are research collaborators and jolly nice chaps to boot.

The story of our lives

We live our lives in fragments, but make sense of them as stories. Scattered islands of experience are drawn together in personal travelogues that attempt explain how our erratic journeys brought us to the present moment.

This is perhaps our most natural and chaotic form of self-understanding but also one of the most vexing for psychology. We know our life stories are mostly fiction, despite their personal force, and much modern psychology has demonstrated how we tend to unknowingly self-justify rather than critically self-appraise.

But it is also the area where personal meaning is its strongest, and where our our lab studies fail most obviously in bridging the chasm between evidence and experience.

Nevertheless, some psychologists are trying to make the leap, and Jesse Bering unravels the yarn in a thought-provoking article for Scientific American.

Traditionally, the psychology of life history has a bad reputation. Known as psychobiography, it was originally created by the neurologist Paul M√∂bius who wrote biographies that not only described the events in the lives of great people, but also attempted to explain their psychological drives and motivations.

It was quickly picked up by Freud, who wrote a series of psychoanalytic biographies, on Moses, da Vinci, Dostoyevsky and Woodrow Wilson, that are widely regarded as his poorest works.

Replete with factual errors and implausible interpretations, he nevertheless spawned a tradition of indulgent psychobiography that sullied the practice for years to come.

In recent years, attempts at psychological biographies have re-emerged in more measured and more successful forms. Alan Elms’ 1993 book Uncovering Lives: The Uneasy Alliance of Biography and Psychology carefully coaxed the practice into the light, and contains some wonderfully sensitive biographies, including, ironically, of Freud himself.

Bering’s article is interesting because he touches on psychologists who are attempting to understand how personality influences our personal storytelling styles, and how our knowledge of autobiographical memory integrates into this process.

In a wonderfully recursive twist, researchers are now trying to integrate the fragments of lab-based knowledge into the fabric of personal narrative, because everything, ultimately, is a story.

Link to Bering on ‘The Psychological Science of Life History Research’.
Link to details of Elms’ awesome book Uncovering Lives.

The morning after the knife before

In the long history of outrageous drinking stories, this has got to be one of the best.

The Emergency Medical Journal has a case study of a man who woke up in hospital after being admitted for alcohol poisoning. He couldn’t remember what happened the night before but when his hangover didn’t clear a precautionary brain scan revealed a knife blade embedded in his temporal lobe.

A left handed, 22‚ÄÖyear old man was brought to the hospital by friends at 0200 because of alcohol intoxication. Events preceding the admission and motivation for the patient to go to the hospital were unclear. The patient’s relatives confessed to a binge drinking of rum and beer, and then being moved suddenly, probably to avoid police control…

The patient woke up 8‚ÄÖhours after admission, complaining of severe headache covering the whole head and gradually increasing in intensity… Surprisingly, brain computed tomography revealed a right temporal haematoma 34‚ÄÖmm in diameter, with a knife blade that had entered from the temporal fossa and was deeply retained in the right temporal lobe (fig 1).

The foreign body was surgically withdrawn, and postoperative recovery was uneventful. After awakening from surgery, the patient could not remember involvement in an altercation, but witnesses retrospectively confirmed that he was attacked with a knife after drinking with his assailant.

There’s also a lovely sentence in the paper which has an apt typo: “Vigorous stimulations only induced growling and repelling movements of the harms and legs”.

Link to ‘an unusual cause for headache following massive alcohol intake’.

The Broken

I seem to have accidentally written dialogue about the Capgras delusion for the 2008 psychological horror film The Broken.

The therapist in this clip says “Have you ever heard about the Capgras syndrome? It’s a rare disorder in which a person holds a belief that an acquaintance, usually a close family member or spouse has been replaced by an identical looking imposter.”

This is taken from the Wikipedia entry for the Capgras delusion, the first sentence of which I wrote in the first version way back in 2003.

The film, by the way, is excellent with a fantastic twist ending, although it stops at what I thought was perhaps the most interesting part when the character realises the truth and attempts to comprehend what this means about herself.

Anyway, my next project is to get a line from the schizophrenia article into a Madonna song.

Wish me luck.

Link to clip from The Broken.
Link to Wikipedia entry for the Capgras delusion.

Back channelling to the future

The staff at Link√∂ping University joke that the cognitive science students have kogvet-sjukan, Swedish for ‘cognitive science disorder’, because they have an incurable enthusiasm for anything related to understanding the mind. After two fantastic days at a conference there, I can see why.

I’ve been to a fair few conferences in my time, but few have been as friendly, interesting and well-organised as KVIT, and it is all the more impressive that it is entirely organised by students.

One of the most bits for me was linguist Jens Allwood’s talk on intercultural communication, where he described cultural differences in how people manage conversation flow.

I’ve always been fascinated by why people from some cultures make sounds during conversations that, to my English-attuned ears, sound unusual. For example, Japanese speakers often make expressions of surprise or interest that seem quite colourful.

These ‘yes, I’m listening’ or ‘yes, continue’ vocal prompts and noises that we make are known as ‘back channelling’, and can also include movements such as nods, or the use of eye-contact.

In some cultures, such as in Japan, eye contact is used far less during conversation, because it might be considered too intense, or it’s considered disrespectful, or even threatening.

So people from cultures that use less eye contact need to signal that they’re following the conversation in other ways, and hence they rely much more on vocal noises, which, to many English speakers, sounds a little odd.

In contrast, people from cultures where eye-contact is frequently used during conversations, like in Latino countries, speakers typically use much less vocal back channelling.

There’s a great review of some of this research in one of Allwood’s papers that’s available online as a pdf.

The others speakers at the conference included an art curator, a primate researcher, an AI consciousness engineer, a psychologist, an interaction designer and an emergency response co-ordinator, all of whom apply cognitive science to their work. Can you think of a more interesting line-up?

However, despite it being attended by people from Holland, Germany, and countries across Scandanavia, I was surprised to see few people from the rest of Europe.

As perhaps one of the best kept secrets in cognitive science, you should seriously consider going next year. The kogvet-sjukan affected Swedes will give you a warm welcome, stimulate your brain and put on impressive dinners with a tradition of raucous and risqu√© cognitive science sketches and songs.

Link to KVIT conference page.
pdf of Allwood’s chapter on intercultural communication.

2009-05-08 Spike activity

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

The excellent Holford Watch blog has a right-on-target debunking of a Daily Mail article that uncritically reprinted dodgy ‘hole in brain’ SPECT scans to ‘show’ we’re “wrecking” our brains with caffeine, alcohol, bad living etc.

Harvard Magazine discuss how their neuroscientists are working to ‘untangle the brain: from neuron to mind’.

Daniel Lende, co-founder of the brilliant Neuroanthropology blog, wins a university award for his work on the anthropology of drug use, HIV, PTSD and his online writing. I think this is the first time I’ve ever seen a blog being recognised by mainstream academia. Congratulations!

New Scientist reports on commercial text analysis programmes that rate emotional content.

There’s a brief but good infographic about the history and development of ‘behavioural economics‘ in Foreign Policy magazine.

Scientific American on recent revelations that Masters and Johnson may have faked their ‘gay cure’ case studies.

Eavesdrop on the world! I’ve just discovered searching Twitter for ‘overheard‘.

Science Policy magazine has an article about what the recent fMRI ‘voodoo’ criticisms mean for the role of fMRI in court. This month’s Wired UK has an awesome article on similar territory, but it’s not available online yet.

Researchers find the earliest signs of autism in infancy, reports Time magazine.

Time magazine reports on the recent STAR*D study that used ‘real world’ patients for an antidepressant trial, rather than the highly selected samples usually used, and found that rates of improvement were less.

New antipsychotic iloperidone is approved by the FDA, reports Furious Seasons.

New Scientist reports that IQ correlates with health and there are hints that some of the relationship might be explained by common genetic factors.

There’s an excellent post about pop stars, drug use, society and double standards at Frontier Psychiatrist.

Cognition and Culture has an interesting piece on cross-cultural variation in creationism.

A genetic study into narcolepsy, a disorder where people suddenly and uncontrollable fall asleep, finds an intriguing link with genes for the immune system. Science News covers the discovery.

Developing Intelligence covers a lovely study finding that physically taking a step back is associated with improved problem-solving.

A concert combining the music of Yo-Yo Ma and the neuroscience of Antonio Damasio is reviewed in The New York Times. There are also some interesting comments from Jonah Lehrer who also saw the performance.

Cognitive Daily cover a study that possibly tells us why it’s hard to ignore that attractive stranger that walks past, even when we’re with our partner.

Why does the vaccine/autism controversy live on? asks Discover Magazine in an article that discusses the social factors behind the deadly but popular myth.

Advances in the History of Psychology has an interview with the author of a new book on Skinner.

Exploding head syndrome

I’ve just found an article with two interesting cases of ‘exploding head syndrome’ – a medical condition where affected people spontaneously hear an exceptionally loud explosion-like noise.

The condition is relatively harmless, causing people only to be startled, and it doesn’t seem linked to seizure activity or epilepsy. Owing to the fact it’s both benign and uncommon, it’s not been widely studied and so its cause remains a mystery.

Case 1
A 48-year-old man was seen in December 2006. For the past several months about three to four times a month, he had been having attacks of a peculiar sensation in the head likened to the noise of an exploding bomb only at night while going off to sleep. The ‘explosion’ would wake him up and disappear completely the moment he woke up.

There was no headache and no associated symptoms such as nausea, vomiting or any visual sensation. For the past 3 months, the frequency of these sensations had increased and had been occurring nearly daily at the time of consultation. The noise occurred only once during every night, after which he could go off to sleep. His past medical history had been unremarkable and he had never suffered from any significant headache problem. General physical and neurological examination had been unremarkable. Magnetic resonance imaging (MRI) of brain with contrast had been normal. He was prescribed Flunarazine 10 mg daily. At 6 months’ follow-up he had much improved and noticed the exploding head symptom only on two occasions.

Case 2
A 65-year-old man was seen in February 2007. He was hypertensive and diabetic (both well controlled on oral medication) and had been having infrequent attacks of International Headache Society migraine headache (every 2‚Äì4 months) without aura since the age of 15 years. For the past 4 months prior to consultation, every 2‚Äì3 weeks, he had been awakened while going off to sleep only during taking a daytime nap by a sudden exploding (like a bomb bursting) noise in his head lasting for only few moments.

This noise was always accompanied with jerky elevation of his right arm and a queer sensation in the right side of his chest (not arm) and again lasting only momentarily. He felt quite well on waking up and could go off to sleep again. These were never accompanied by any visual flashes and never occurred during sleep at night. These sensations were very different from his migraine headaches, which lasted for several hours and the noises were not accompanied by any nausea or vomiting.

Physical examination was normal and his blood presswure in the clinic was 136/80 mmHg. He had already had a MRI of brain with contrast, MR angiography of brain and two interictal sleep EEG recordings performed before consultation with the author, all of which were normal. A video EEG with daytime sleep recording was performed, but no event could be captured.

Link to article with case studies.
Link to PubMed entry for same.