Category: Moving

Why do we like to listen to tunes when we exercise? Psychologist Tom Stafford searches for answers within our brains, not the muscles we are exercising.

Perhaps you have a favourite playlist for going to the gym or the park. Even if you haven’t, you’re certain to have seen joggers running along with headphones in their ears. Lots of us love to exercise to music, feeling like it helps to reduce effort and increase endurance. As a psychologist, the interesting thing for me is not just whether music helps when exercising, but how it helps.

One thing is certain, the answer lies within our brains, not the muscles we are exercising. A clue comes from an ingenious study, which managed to separate the benefits of practicing a movement from the benefits of training the muscle that does the movement. If you think that sounds peculiar, several studies have shown that the act of imagining making a movement produces significant strength gains. The benefit isn’t a big as if you practiced making the movement for real, but still the benefit of thinking about the movement can account for over half of the benefit of practice. So asking people to carry out an imaginary practice task allows us to see the benefit of just thinking about a movement, and separates this from the benefit of making it.

Imaginary practice helps because it increases the strength of the signal sent from the movement areas of the brain to the muscles. Using electrodes you can record the size of this signal, and demonstrate that after imaginary practice people are able to send a stronger, more coherent signal to the muscles.

The signals to move the muscles start in an area of the brain called, unsurprisingly, the motor cortex. It’s in the middle near the top. Part of this motor area is known as the supplementary motor cortex. Originally thought to be involved in more complex movements, this area has since been shown to be particularly active at the point we’re planning to make a movement, and especially crucial for the timing of these actions. So, this specific part of the brain does a very important job during exercise, it is responsible for deciding exactly when to act. Once you’ve realised that a vital part of most sporting performance is not just how fast or how strong you can move, but the effort of deciding when to move, then you can begin to appreciate why music might be so helpful.

The benefits of music are largest for self-paced exercise – in other words those sports where some of the work involved is in deciding when to act, as well as how to act. This means all paced exercises, like rowing or running, rather than un-paced exercises like judo or football. My speculation is that music helps us perform by taking over a vital piece of the task of moving, the rhythm travels in through our ears and down our auditory pathways to the supplementary motor area. There it joins forces with brain activity that is signalling when to move, helping us to keep pace by providing an external timing signal. Or to use a sporting metaphor, it not only helps us out of the starting blocks but it helps to keep us going until we reach the line.

Of course there are lots of other reasons we might exercise to music. For example, a friend of mine who jogs told me: “I started running to music so I didn’t have to listen to my own laboured breathing.” He might well have started for that reason, but now I’ll bet the rhythm of the music he listens to helps him keep pace through his run. As one song might have put it, music lets us get physical.

This is my BBC Future column from last week. The original had the much more accessible title of “The Psychology of Workout music“, but mindhacks.com is our site (dammit) and I can re-title how I want.

Here’s my column at BBC Future from last week. You can see the original here. The full listof my columns is here and  there is now a RSS feed, should you need it

As we give up our bodies to sleep, sudden twitches escape our brains, causing our arms and legs to jerk. Some people are startled by them, others are embarrassed. Me, I am fascinated by these twitches, known as hypnic jerks. Nobody knows for sure what causes them, but to me they represent the side effects of a hidden battle for control in the brain that happens each night on the cusp between wakefulness and dreams.

Normally we are paralysed while we sleep. Even during the most vivid dreams our muscles stay relaxed and still, showing little sign of our internal excitement. Events in the outside world usually get ignored: not that I’d recommend doing this but experiments have shown that even if you sleep with your eyes taped open and someone flashes a light at you it is unlikely that it will affect your dreams.

But the door between the dreamer and the outside world is not completely closed. Two kinds of movements escape the dreaming brain, and they each have a different story to tell.

Brain battle

The most common movements we make while asleep are rapid eye-movements. When we dream, our eyes move according to what we are dreaming about. If, for example, we dream we are watching a game of tennis our eyes will move from left to right with each volley. These movements generated in the dream world escape from normal sleep paralysis and leak into the real world. Seeing a sleeping persons’ eyes move is the strongest sign that they are dreaming.

Hypnic jerks aren’t like this. They are most common in children, when our dreams are most simple and they do not reflect what is happening in the dream world – if you dream of riding a bike you do not move your legs in circles. Instead, hypnic jerks seem to be a sign that the motor system can still exert some control over the body as sleep paralysis begins to take over. Rather than having a single “sleep-wake” switch in the brain for controlling our sleep (i.e. ON at night, OFF during the day), we have two opposing systems balanced against each other that go through a daily dance, where each has to wrest control from the other.

Deep in the brain, below the cortex (the most evolved part of the human brain) lies one of them: a network of nerve cells called the reticular activating system. This is nestled among the parts of the brain that govern basic physiological processes, such as breathing. When the reticular activating system is in full force we feel alert and restless – that is, we are awak

Opposing this system is the ventrolateral preoptic nucleus: ‘ventrolateral’ means it is on the underside and towards the edge in the brain, ‘preoptic’ means it is just before the point where the nerves from the eyes cross. We call it the VLPO. The VLPO drives sleepiness, and its location near the optic nerve is presumably so that it can collect information about the beginning and end of daylight hours, and so influence our sleep cycles. As the mind gives in to its normal task of interpreting the external world, and starts to generate its own entertainment, the struggle between the reticular activating system and VLPO tilts in favour of the latter. Sleep paralysis sets in.

What happens next is not fully clear, but it seems that part of the story is that the struggle for control of the motor system is not quite over yet. Few battles are won completely in a single moment. As sleep paralysis sets in remaining daytime energy kindles and bursts out in seemingly random movements. In other words, hypnic jerks are the last gasps of normal daytime motor control.

Dream triggers

Some people report that hypnic jerks happen as they dream they are falling or tripping up. This is an example of the rare phenomenon known as dream incorporation, where something external, such as an alarm clock, is built into your dreams. When this does happen, it illustrates our mind’s amazing capacity to generate plausible stories. In dreams, the planning and foresight areas of the brain are suppressed, allowing the mind to react creatively to wherever it wanders – much like a jazz improviser responds to fellow musicians to inspire what they play.

As hypnic jerks escape during the struggle between wake and sleep, the mind is undergoing its own transition. In the waking world we must make sense of external events. In dreams the mind tries to make sense of its own activity, resulting in dreams. Whilst a veil is drawn over most of the external world as we fall asleep, hypnic jerks are obviously close enough to home – being movements of our own bodies – to attract the attention of sleeping consciousness. Along with the hallucinated night-time world they get incorporated into our dreams.

So there is a pleasing symmetry between the two kinds of movements we make when asleep. Rapid eye movements are the traces of dreams that can be seen in the waking world. Hypnic jerks seem to be the traces of waking life that intrude on the dream world.

I’ve just found another video of the Lazarus sign, the spinal reflex that triggers an arm raising and crossing movement in recently brain dead patients.

We’ve covered the mechanism behind the somewhat disconcerting movement before, and have noted an earlier video, but this one seems to have been uploaded quite recently.

The movement is triggered by a reflex arc – a basic neural circuit that doesn’t go any further than the spinal cord which means that it can initiate movement even when the brain is non-functional.

When the doctor taps your knee and causes a knee jerk, he or she is triggering exactly this effect. In fact, these movements can be triggered all over the body.

If you’ve ever had a complete neurological examination the neurologist will tap on various points to trigger numerous reflex arcs to check that the nerves going to and from certain muscle groups are in good working order.

One of these arcs causes the movement in the Lazarus sign, which, needless to say, can be quite disconcerting for doctors and quite confusing for relatives if the patient has just passed way.

In fact, you can see from the video how ‘lifelike’ the movement seems.

Probably not recommended if you’re uncomfortable with the sight of recently dead people moving.
 

Link to video of Lazarus sign.

Enjoying the Natural History Museum yesterday, I came across this exhibit somewhere in the geology section:

The exhibit is a serious of columns, which you pass from right to left. The penultimate column is to illustrate the idea of ice, and you’re invited by a palm shape to put your palm to the column (which is indeed cold). The interesting thing is the final column, which is meant to illustrate gravity somehow (it was broken yesterday, so I don’t know how it is supposed to do this). Notice how the metal around the IVY of gravity is worn away. None of the other columns had this. Obviously hundreds of visitors a day are drawn to this exhibit, press their palms to the ICE column and then go on to touch, in exactly the same way, the GRAVITY column even though this isn’t part of the way they are supposed to interact with the exhibit.

Psychologists know that what people have done before is the best predictor of what they will do in the future. Whole industries are devoted to helping us establish, or break, habits. This exhibit on geological forces illustrates how easily some behavioural precedents can be set. We love touching things, and although we aren’t meant to, permission to do it once is all that is required to set off an immediate repetition of the behaviour.

A brief yet intriguing description of a talk on pointing, by the ever versatile neuroscientist and philosopher Ray Tallis at the recent Hay Literary Festival.

A spellbinding hour with philosopher and self-confessed “many-layered anorak” Raymond Tallis on the subject of pointing. Yes, sticking your finger in the air and directing it at an object. It is, he argued, one of the attributes that mark us out as human beings with a sense of ourselves and others in a shared space: no other animal, including pointers and chimps, can use pointing fully. He reflected on its use for babies as a staging post towards acquiring language; and noted that in autistic children there is often an absence of pointing. He talked about pointing and power: the pointing that marks some unfortunate from a crowd and summons them to who-knows-what; the Malcolm Tucker-esque jabbing of the air that is tantamount to “a one-fingered punching at the self”. Then there is the disembodied, absent, generalised pointing of the fingerpost, which has “the ghost of intention about it”.

Link to description in The Guardian (via @Matthew_Broome)

Two things I love are sleeping and data collection. Now, thanks to a new iPhone app, I can do both at once.

Sleep Cycle uses the accelerometer in the iPhone to record vibrations in your mattress caused by you moving in the night. In this way it acts as an actigraph, keeping a record of your body movement, which in this context reflects how deeply you are asleep.

Here is the data from my last night’s kip. As you can see I show a fairly typical pattern: sleeping deeper in the first half of the night, compared to the second half, and having alternating patterns of deep and light sleep (although I seem to cycle through the stages of sleep every hour, rather than the typically quoted every one and a half hours).

The app also has an alarm which promises to wake you up during a lighter stage of sleep, so saving you the unpleasant sensation of being woken by your alarm from deep sleep. I’ve yet to try this out but it sounds like a good thing, as long as avoiding the jarring sensation is worth forgoing the extra minutes shut-eye!

Link: to the Sleepcycle app

Last night, I walked past a bus stop adorned with a poster advertising the new BBC science programme Bang Goes the Theory asking “Is it possible to tickle yourself?” and giving a number to text for an explanation.

Fantastic, I thought. Neuroscientist Sarah-Jayne Blakemore’s work on the role of action prediction in the sensory attenuation of self-produced actions summarised in 160 characters.

But here’s the response I got sent to my phone:

Your brain tells your body not to react when you tickle yourself hard, but skin with no hair is sensitive to a light touch. More at http://bbc.co.uk/bang

Admittedly, I was a little worse for wear last night, but even in the cold hard light of day, this doesn’t make a lot of sense.

The second bit (“skin with no hair is sensitive to a light touch”) just seems irrelevant to the question, the webpage has nothing more and the actual explanation is kinda screwy.

Your brain is not telling your body not to react because, except for reflex actions (which are handled by reflex arcs and can be managed entirely by the spinal cord), sensory reactions are handled by the brain.

So if you’re taking this line, a more accurate description is that your brain is telling your brain not to react but this still explains virtually nothing about why you can’t tickle yourself.

However, a scientific paper [pdf] entitled ‘Why can’t you tickle yourself?’ addresses exactly this question.

The science of this is quite well known (in fact, it was featured in the original Mind Hacks book as Hack #65) but in summary it seems that the brain simulates of the outcomes of actions based on your intentions to move because the actual sensory information from the body takes so long to arrive that we’d be dangerously slow if we relied only on this.

This slower information is used for periodic updates to keep everything grounded in reality, but it looks like most of our action is run off the simulation.

We can also use the simulation to distinguish between movements we cause ourselves and movements caused by other things, on the basis that if we are causing the movement, the prediction is going to be much more accurate.

If the prediction is accurate, the brain reduces the intensity of the sensations arising from the movement – for good safety reasons, perhaps – we want to be more aware of contact from other things than touches from ourselves.

So Aunty BBC, here’s one you can use for free:

Your brain predicts the effects of movement and reduces sensations if it guesses right. We guess our own actions better, so it tickles less. http://is.gd/2978A

The next one will cost you the 10p I spent texting Bang Goes the Theory for an inaccurate explanation.

pdf of scientific paper ‘Why can’t you tickle yourself?’
Link to Hack #65 in Mind Hacks.

A simple but elegant study just published in the European Journal of Social Psychology found that getting people to generate words about pride caused them to unknowingly raise their posture, while asking them to generate words about disappointment led to an involuntary slouch.

The research team, led by psychologist Suzanne Oosterwijk, asked people to list words related to ‘pride’ and ‘disappointment’, and some emotionally neutral control categories of ‘kitchen’ and ‘bathroom’, while being secretly filmed.

‘Pride’ caused a slight increase in posture height, while ‘disappointment’ caused the participants to markedly slouch.

The researchers suggest that the activation of the concept of disappointment led to a spontaneous bodily simulation of the feeling. They link this to the idea of embodied cognition that suggests that our mental life is fundamentally connected to acting on the world.

As we discussed last year, research has suggested that bodily expressions of pride and shame are the same across cultures, indicating that this connection between action and emotion may be a core part of our emotional make-up.

Link to abstract of study (via the BPSRD).

Damn this is cool. The New York Times has an article on an innovative technology that allows people to naturally use mechanical prosthetic arms.

While most of the media attention has been focused on implanting electrodes directly into the brain as a form of ‘neuroprosthetics’, this technology takes a novel and remarkably ingenious approach with impressive results.

The technique, called targeted muscle reinnervation, involves taking the nerves that remain after an arm is amputated and connecting them to another muscle in the body, often in the chest. Electrodes are placed over the chest muscles, acting as antennae. When the person wants to move the arm, the brain sends signals that first contract the chest muscles, which send an electrical signal to the prosthetic arm, instructing it to move. The process requires no more conscious effort than it would for a person who has a natural arm.

Researchers reported Tuesday in the online edition of The Journal of the American Medical Association that they had taken the technique further, making it possible to perform 10 hand, wrist and elbow movements, a big improvement over the typical prosthetic repertoire of bending the elbow, turning the wrist, and opening and closing the hand.

It’s an inventive technique because it takes a whole chunk of the hard work away from the technology.

With neural implants, the major obstacle is developing the technology to reduce the noisy neural information into simpler signal channels. The patient then needs to be trained to generate the right brain activity to funnel the activity into the broad channels of the digital signal processor.

This technology takes advantage of existing healthy nerves but just reassigns them to other muscles and the activity in these is just converted into mechanical actions.

Of course, it isn’t useful for people who are completely paralysed, but the results are quite spectacular.

The article has an embedded video which illustrates the remarkable dexterity that the woman with the prosthetic arm is able to achieve.

The scientific article describing the technology has just been published in the Journal of the American Medical Association and describes five prosthetic limb patients who were asked to complete a number of manual dexterity tests.

The study found that they completed tasks only marginally less well than comparison participants who had no damage and were using their original arms.

UPDATE: Mo has reminded me that Neurophilosophy covered an single case of the same procedure earlier in its development cycle. Mo also notes that the technology has the potential to feed-back touch information to the phantom limb!

Link to NYT article ‘In New Procedure, Artificial Arm Listens to Brain’.
Link to scientific article.
Link to JAMA entry for same.

Mirror’s Edge is a first person computer game in which you play an urban free-runner, leaping, sliding, and generally acting fly across the roofs of a dystopian city (see the trailer here). It looks good. In fact, it looks amazing. But, reportedly, to actually play it is even better, sickeningly better.

Clive Thompson, writing for wired.com, suggests that the total interactivity of the environment (if you can see something, you can jump on it, or off it) along with the visual cues about what your character’s arms and legs are doing (they appear in shot as you run and jump) makes the game a convincing proprioception hack. In other words, it remaps your body schema so that you feel more fully that you are the character in the game. When your character runs fast, you feel it is you running fast. When you character jumps across between two buildings and look down, you feel a moment of sickening vertigo.

Research into illusions of proprioception — your sense of where you body is in space — has shown that our body map is surprisingly flexible. It is possible to mislocate your hand, for example, coming to believe that it is directly in front of you when in fact out at the side, or behind you (see video here). Jaron Lanier has reported on an early virtual reality experience he had that made him feel like he had the body of a lobster, with 6 extra limbs. The important feature of all these illusions is that they rely on precisely timed visual feedback. Although visual input can reprogramme our body image, it only does so when there is a tight coupling between what we see and feel. The importance is not the level of detail in what we see, but in the fluidity of the interaction. If Mirror’s Edge makes you feel like you are really are doing Parkour then it is because it has the correct kind of visual feedback (your limbs, in a fully interactive world) with the correct timing.

A final thought: if a computer game really is immersive for something as visceral as free-running, isn’t that kind of surprising, given how complex free running is physically, and how simple the commands used to control a computer game are? Perhaps what this is because when we automatise an action such as a run, a jump or a roll part of the process of making it automatic is losing the experience of the component parts. So, when a computer game feels like real, it is because real feels like nothing — we just ask our brains ‘jump’ and the motor system sorts out the details without our any deep experience of how the jump is performed.

link Clive Thompson’s report on playing Mirror’s Edge
link YouTube trailer for the game

Wired Science covers an elegant study that suggests that spontaneous expressions of pride and shame are innate behaviours that are not significantly influenced by culture.

The researchers came up with the ingenious idea of comparing how judo wrestlers from the 2004 Olympics and blind judo wrestlers from the 2004 Paralympics celebrated and commiserated their matches.

This allowed a cross cultural comparison, but it also allowed a comparison with blind athletes who have never seen another person in the same position to copy their behaviour.

The new research, however, distilled from high-resolution, high-speed photographic sequences of sighted and blind judo competitors at the 2004 Olympics and Paralympics, suggests that most nonverbal responses to wins and losses are almost universal.

No cultural differences were observed among competitors from different countries and, aside from the shaking of the fists after a loss, sighted and blind athletes displayed remarkably similar nonverbal behavior.

In other words, it made virtually no difference what culture each individual came from, or even whether the person had seen another wrestler at the end of a match or not – the expression of pride was indistinguishable, suggesting that this may be a common expression that we all share.

There was a slight effect of culture on the expression of shame – as the researchers note “it was less pronounced among individuals from highly individualistic, self-expression-valuing cultures, primarily in North America and West Eurasia”.

However, as there was no difference within cultures between sighted and blind individuals, they further suggest that both pride and shame are likely to be innate, but that shame display may be intentionally inhibited by some sighted individuals in accordance with cultural norms.

Link to Wired Science on elegant study.
Link to full text of paper.

I’m going to tell you about an experience that I often have rock-climbing and then I’m going to offer you some speculation as to the cognitive neuroscience behind it. If you rock-climb I’m sure you’ll find my description familiar. If you’re also into cognitive neuroscience perhaps you can tell me if you think my speculation in plausible.

Rock-climbing is a sort of three-dimensional kinaesthetic puzzle. You’re on the side of rock-wall, and you have to go up (or down) by looking around you for somewhere to move your hands or feet. If you can’t see anything then you’re stuck and just have to count the seconds before you run out of strength and fall off. What often happens to me when climbing is that I look as hard as I can for a hold to move my hand up to and I see nothing. Nothing I can easily reach, nothing I can nearly reach and not even anything I might reach if I was just a bit taller or if I jumped. I feel utterly stuck and begin to contemplate the immanent defeat of falling off.

But then I remember to look for new footholds.

Sometimes I’ve already had a go at this and haven’t seen anything promising, but in desperation I move one foot to a new hold, perhaps one that is only an inch or so further up the wall. And this is when something magical happens. Although I am now only able to reach an inch further, I can suddenly see a new hold for my hand, something I’m able to grip firmly and use to pull myself to freedom and triumph (or at least somewhere higher up to get stuck). Even though I looked with all my desperation at the wall above me, this hold remained completely invisible until I moved my foot an inch — what a difference that inch made.

Psychologists have something they call affordances (Gibson, 1977, 1986), which are features of the environment which seem to ‘present themselves’ as available for certain actions. Chairs afford being sat on, hammers afford hitting things with. The term captures an observation that there is something very obviously action-orientated about perception. We don’t just see the world, we see the world full of possibilities. And this means that the affordances in the environment aren’t just there, they are there because we have some potential to act (Stoffregen, 2003). If you are frail and afraid of falling then a handrail will look very different from if you are a skateboarder, or a freerunner. Psychology typically divides the jobs the mind does up into parcels : ‘perception’, (then) ‘decision making’, (then) ‘action’. But if you take the idea of affordances seriously it gives lie to this neat division. Affordances exist because action (the ‘last’ stage) affects perception (the ‘first’ stage). Can we experimentally test this intuition, is there really an effect of action on perception? One good example is Oudejans et al (1996) who asked baseball fielders to judge were a ball would land, either just watching it fall or while running to catch it. A model of the mind that didn’t involve affordances might think that it would be easier to judge where a ball would land if you were standing still; after all, it’s usually easier to do just one thing rather than two. This, however, would be wrong. The fielders were more accurate in their judgements — perceptual predictions basically — when running to catch the ball, in effect when they could use base their judgements on the affordances of the environment produced by their actions, rather than when passively observing the ball.

The connection with my rock-climbing experience is obvious: although I can see the wall ahead, I can only see the holds ahead which are actually within reach. Until I move my foot and bring a hold within range it is effectively invisible to my affordance-biased perception (there’s probably some attentional-narrowing occurring due to anxiety about falling off too, (Pijpers et al, 2006); so perhaps if I had a ladder and a gin and tonic I might be better at spotting potential holds which were out of reach).

There’s another element which I think is relevant to this story. Recently neuroscientists have discovered that the brain deals differently with perceptions occurring near body parts. They call the area around limbs ‘peripersonal space’ (for a review see Rizzolatti & Matelli, 2003). {footnote}. Surprisingly, this space is malleable, according to what we can affect — when we hold tools the area of peripersonal space expands from our hands to encompass the tools too (Maravita et al, 2003). Lots of research has addressed how sensory inputs from different modalities are integrated to construct our brain’s sense of peripersonal space. One delightful result showed that paying visual attention to an area of skin enhanced touch-perception there. The interaction between vision and touch was so strong that providing subjects with a magnifying glass improved their touch perception even more! (Kennett et al, 2001; discussed in Mind Hacks, hack #58). I couldn’t find any direct evidence that unimodal perceptual accuracy is enhanced in peripersonal space compared to just outside it (if you know of any, please let me know), but how’s this for a reasonable speculation — the same mechanisms which create peripersonal space are those which underlie the perception of affordances in our environment. If peripersonal space is defined as an area of cross-modal integration, and is also malleable according to action-possibilities, it isn’t unreasonable to assume that an action-orientated enhancement of perception will occur within this space.

What does this mean for the rock-climber? Well it explains my experience, whereby holds are ‘invisible’ until they are in reach. This suggests some advice to follow next time you are stuck halfway up a climb: You can’t just look with your eyes, you need to ‘look’ with your whole body; only by putting yourself in different positions will the different possibilities for action become clear.

(references and footnote below the fold)

Continue reading “Rock climbing hacks! (now with added speculation)”

BBC Radio 4’s All in the Mind just broadcast a wonderfully eclectic edition with pieces on parapsychology and why people hold paranormal beliefs, the psychology of laughter, and the military applications of neuroscience.

Dr Caroline Watt and Prof Chris French discuss both the current boom in scientific parapsychology research and the psychology of paranormal belief.

Prof Mark Van Vugt talks about the social function of laughter, something we featured the other day.

Finally, Prof Jonathan Moreno, author of the excellent Mind Wars, discusses the military applications of neuroscience, something he also tackled in a 2006 SciAmMind article.

Ghosts, gags and grunts. What a great combination!

Link to edition of BBC AITM with online audio.

PsyBlog has just published a couple of short articles on non-verbal communication, one examining a common myth, and the other looking at how it indicates attraction between people who’ve just met.

The first article is on the research that debunks the myth that ‘93% of communication is nonverbal’.

Just the precision of those sorts of statements make me suspicious. To quote the wise words of comedian Vic Reeves “88.2% of statistics are made up on the spot”.

The second article examines a study that looked at the dynamic patterns of non-verbal communication when men and women met for the first time, and looked at how these patterns were related to attraction.

Contrary to many previous findings, attraction was predicted by patterns of synchronisation and not simple mirroring of body language. What emerged were rhythmic structures of movement synchrony – patterns of bodily movement people adopted. In common with previous research, Grammer et al. (1998) found it was women who tended to start and control these patterns. Indeed, the more interested a woman was in a man, the more complicated these patterns became.

There’s more on this impressive study in the PsyBlog article.

Link to article on myth of non-verbal communication.
Link to article ‘The Nonverbal Symphony of Attraction’.