News
Research news
Oxytocin - the elixir of trust
There's a real buzz in the air in the mainstream and academic worlds about a hormone called oxytocin. It's being called variously: the cuddle, love, generosity and trust hormone. Believe it or not, you can even buy it online as a nasal spray called Liquid Trust!
Researchers discovered some time ago that sniffing oxytocin boosts its levels in the human brain. It's well known that oxytocin is a powerful hormone but the reason for all the excitement is the publication of a series of research studies that reveal some of oxytocin's other powers
A dose of oxytocin increases generosity in humans by 80% and doubles our ability to trust someone. It's specific too - it only works with human contact; trust does not increase if it's a computer game.
Oxtytocin's bond-creating properties
It's been well known for years that oxytocin promotes social bonding. Oxytocin is a chemical produced naturally in every human brain to induce relaxation and giving us a warm glow. It reduces blood pressure and stress/anxiety (cortisol levels) in both sexes but particularly so in women.
Oxytocin levels go up when someone else touches us both physically and emotionally. One study found that women holding hands with their partners, maintaining eye contact, and lying together all raised oxytocin levels. However, they found the most effective increase - over 20% - was achieved by stroking the hands, neck or back. This explains why massage creates that great feeling of relaxation.
Breastfeeding stimulates oxytocin production in both mother and child. The connection between milk production and oxytocin promotes the mother-baby bond. Many women report that drowsy feeling of relaxation and pleasure they get when they breast feed. The baby feels it too - so mum and child are at one, feeling good together. It's the bonding hormone in animals. Experiments that block its action result in mother rats rejecting their babies.
Oxytocin's role in the bedroom
Oxytocin is linked directly to sexual pleasure, rising with sexual desire in both sexes and peaking at orgasm. It creates that 'after glow' of serenity and closeness that happens after orgasm. Women are used to it - it makes then want to cuddle and talk. But it can send the man to sleep. The drowsy effect wears of fast in men as his testosterone, also high at orgasm, destroys it swiftly. He will soon be hopping out of bed to do something but she will still want to cuddle and talk. Women take his behaviour as a sign that he does not really love her - that he just wants sex. But just understanding this gender difference can reduce some common post-sex misunderstandings.
Oxytocin is higher in women than men, the main reason being that oxytocin interacts with the sex hormones already present in our system. The female hormone oestrogen stimulates its production and enhances its effect. It's lower in men because the male hormone testosterone inhibits its production and limits its action.
Sniffing trust and generosity research
Once researchers discovered sniffing or injecting oxytocin increased its levels in the human brain, giving them a tool to investigate and discover the hormone's other powers.
On June 1, 2005, researchers from the University of Zurich announced an astonishing discovery: When people inhale oxytocin, they react by becoming more trusting of other people. The journal Nature published research showing that when subjects played a game that hinged on trust,those who sniffed oxytocin were more likely to trust other players.
Another study in the USA was equally astonishing. Those taking part were given a sum of money and asked to share it with a stranger. Those dosed with oxytocin were 80% more generous than those given the same apparent treatment but lacking the hormone.
The memory booster for faces
The most recent study shows that oxytocin increases our ability to remember faces. Interestingly, this study found that oxytocin increased a person's ability to remember a face but not an object, proving it only works in social situations. Volunteers who used the oxytocin spray more accurately recognised the faces they had seen before than did those in the placebo group. So it's oiling our social wheels as well as making us feel good when we interact.
Why it works - fear reduction
Another finding of the research helps us understand why oxytocin is so closely linked to smoothing the way in many of our social situations. The study used brain scans taken when each individual was shown a series of angry and threatening faces. In those who had been given the placebo instead of the oxytocin, the 'fear centres' of the brain's amygdala were activated - exactly as the researchers expected. In those who had been given oxytocin, there was little or no activity in their brains' fear centres.
Oxytocin, they think, switches off the fear centre or the alarm system in brain. So we feel safe to trust that person, we feel safe to be more generous, more loving. Some experts now think that it could be of some benefit to sufferers of acute shyness and social phobias.
Abusing the elixir of Trust?
But could oxytocin's trust-giving qualities be misused? Could a quick surreptitious squirt of oxytocin be used as a weapon of seduction or even rape? A mist of oxytocin in the air at a supermarket - might that lead to increased sales? Some enterprising company is now selling an oxytocin-laced perfume: Love Scent. Is this inappropriate?
The researchers assure me that it takes a lot of sniffing and high concentrations of the stuff for it to work. You would need to spray someone full force in the face, which would be impossible without the other person knowing. Filling the air with it just wouldn't work either - it would never reach the necessary concentration levels and would cost a small fortune even to try.
References
Katherine Light - the power of love. This is about how physical touch increases oxytocin. http://newsinhealth.nih.gov/pdf/NIHNiH%20February07.pdf
Oxytocin increases trust in humans
Michael Kosfeld et al. Nature 435, 673-676, 2005.
Oxytocin Increases generosity in humans
Paul J. Zak et al. Social science research network
http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1029157
PLoS ONE, Vol. 2, No. 11, 2007
"Oxytocin Makes a Face in Memory Familiar".
Peter Kalver et al. The Journal of Neuroscience, January 7, 2009, 29(1):38-42
Oxytocin Modulates Neural Circuitry for Social Cognition and Fear in Humans
Peter Kirsch et al. The Journal Neuroscience 25 (49): 11489-11493, 2005
Good Reads
The Tending Instinct
Women, Men and the Biology of Our Relationships
Shelly E. Taylor Times books 2002
I picked this book to focus on this month as it complements the oxytocin research in the news section and proposes a new and controversial theory about men and women - one that overturns five decades of stress research. Until Shelly Taylor's research, scientists and laymen alike believed that when we experience stress, it triggers a hormonal cascade that revs the body up to either fight or flee as fast as possible. Taylor argues a quite different case from her own and current research. While stress does indeed produce the fight or flight response in men, women respond with a very different cascade of brain chemicals that cause them to reach out to other women and to bond with them.
It is an academic work so is not an easy read but Taylor's fascinating and interesting new theory makes it well worth the effort. Scientific theories and complex ideas are backed up with evidence that can be directly applied to helping us cope with the stresses of modern life.
Taylor gathered all the research together to show just how different the male female responses to stress are. It is from this evidence she postulated her revolutionary new theory about women's tending instincts.
Fight-Flight versus Tend-Befriend
When we are challenged in a dangerous situation, it triggers what has become known as the fight or flight response; the adrenaline rush that promotes a cascade of neuro-hormonal reactions to prepare us either to run or to stand ground and fight or to run.
The fight or flight response is generally regarded as the prototypic response to stress. It has dominated stress research for the past five decades. What Taylor now suggests is that the flight and flight response is the male response; the female is modified to a different response, which she calls 'tend and befriend'.
Taylor argues that to tend and befriend for the female makes far more sense when considered in the context of our evolution in the wild and dangerous African grasslands.
Evolution and surviving danger
In our evolution our survival depended on the ability to mount a successful response to whatever threat came our way. Taylor argues that is does make evolutionary sense for the male to be ready to fight or flee but not for the female. A pregnant female with babies and young children is not going to increase her family's chances of survival by running. Her survival, and that of her offspring, would have been better served by being part of a large, friendly, female group. For example, if the threat was from a prowling lion, wasn't it more sensible to tend/quiet the children and keep still than to break cover and run? Better also to be in a large group of females as the group itself provides protection. If you look at the behaviour of other primates this is indeed what you see. The females gather in groups and are very successful at defending themselves from the aggressive males in the troupe.
So why has no one put forward this theory before? The reason is that studies on the biochemistry of the fight and flight mechanism were in the past based on studies of men. Women were excluded from the studies because it was considered too complicated to factor in the cyclic fluctuations in the female hormones. In just the last decade research on women is finally being gathered.
Sex differences in stress response
When challenged, level of epinephrine/adrenaline in males is double that in females. Men have a consistently higher response to most, but not all, challenging situations than do women. By contrast, women show more of an adrenaline high in emotionally demanding situations than do men. Cortisol is also a measure of our 'stress levels. If it remains high for a long time it creates that feeling of anxiety. Again, there are differences in the way it presents in men and women.
Cortisol Response
- Cortisol in short bursts helps in demanding situations by sharpening concentration
- If cortisol is too high for too long it harms the body and the brain
- In women the cortisol reaction is stronger and remains longer than in men
The key behavioural mechanism underlying the 'tend and befriend' theory in women draws heavily on the attachment/bonding/care giving system and our old friend from research news: Oxytocin.
Oxytocin and sex differences in stress reduction
Female oxytocin and her stress response:
- The adrenaline response triggers the release of oxytocin
- The female hormone oestrogen enhances the action of oxytocin
- Oxytocin induces relaxation and lowers cortisol
- Oxytocin reduces the stress
- A woman can relieve her feelings of anxiety by caring for others
- Under stress she is neurologically primed to tend
As we learned in the news section, oxytocin is the primary hormone oiling the social networking wheels. It's much more the female pattern when coping with stressful situations.
His pattern of response is different:
Male vasopressin is a hormone related to aggression and the male stress response
- The adrenaline response triggers the release of vasopressin
- The male hormone testosterone enhances the action of vasopressin and inhibit oxytocin
- Vasopressin increases the aggressive response in males
- Under stress he is neurologically primed for fight or flight
So in today's world, it works like this:
Stress reduction in men and women after a day at work
- His cortisol goes up if he has to be sociable
- Her cortisol goes down by talking and communicating
- He needs a period of quiet to de-stress
- She needs to talk to de-stress
An understanding of that difference will help reduce friction between men and women. Just give him 20 minutes of quiet when he gets home to bring his stress down and he will then be ready to talk to help reduce her stress.
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Research news
Are we short changing the boys?
"I have lost count of the time I've heard mothers worrying about their sons not learning to speak, read or write as fast as their sisters or friends' daughters. This month we examine specific brain-based research that proves these mums have no need to worry about theirs sons' slower developmental pace. There is nothing wrong with the boys! Their brains develop language abilities much slower than girls. This, to me, is one of the important findings of neuropsychological research during the past five years."
It has long been known from the research that girls generally learn to walk, talk and read faster than boys. Females perform better on verbal fluency, anagram solution and general tests of verbal ability. These are, of course, generalisations and there are always exceptions. And, as with all statistics, they can only be used to highlight the probability of behavioural patterns, not to predict individual performance.
In the last five years, scientific research has determined the overall brain-based cause for learning pace differences between the sexes:
Brain maturation and brainsex differences
The brain matures at different rates in girls and boys. This is especially true of the areas in the brain controlling language and fine motor skills, which develop faster in girls. Conversely, some areas of boys' brains mature at a faster rate; for example, those governing gross motor control, as evidenced by most boys' ability to kick a ball at an earlier age than their sisters. Spatial ability also develops earlier in the male brain. Young boys are generally going to be better at solving three-dimensional puzzles and building things than their less spatially aware female siblings.
To summarise:
Girls: Verbal areas of the brain mature 4-6 years ahead of the boys.
Fine motor areas, 4-6 years ahead of the boys.
Boys: Spatial ability of the brain matures 2-4 years ahead of the girls;
Gross motor control, 2-4 years ahead of the girls.
Brain maturation is detectable even when the baby is still in the mother's womb, and the differences between the sexes are manifest already.
What it means in the class room
These brain-based developmental differences have major ramifications in early education. In our schools, where such emphasis is placed on verbal ability and the skill to write neatly, are we asking the boys to do things that their brains are not ready for? As our research clearly shows, early primary age schoolboys generally lack the fine motor skills necessary to write the letters of the alphabet neatly. A five- to seven-year-old boy is being asked to perform in the classroom at a level for reading and writing that his brain is not ready for. Johnny sits next to little Jenny, who is doing it all so well and being praised by the teacher. He can see that he is not doing as well as she is and boys are competitive even at that young age. So does the thought pass through his mind: "I'm no good at this", and he then either gives up or plays up?
Sadly, many mothers have told me that their young boys' liveliness and enthusiasm for going to school have been dented very soon after starting their primary education. A few weeks into school life, Johnny comes home all upset, saying he doesn't like school. Is that really so surprising if the curriculum - exactly the same for boys and girls - doesn't allow Johnny and his mates to show off their talents? We are asking them to sit still, write neatly, be quiet. All easily achievable by Jenny and her friends but a real stretch for Johnny's gang!
What's to be done?
Educationalists need to devise ways that allow boys to shine in the area where their brains are developing - specifically the gross motor control and spatial areas. Johnny should be solving three-dimensional puzzles and assembling things until the appropriate areas of his brain have developed sufficiently to match Jenny's neat handwriting skills.
Girls generally do better in school than boys in nearly every subject - and this is especially true in the early years of education. Are we short-changing boys because educationalists have not even begun to apply their brain-based knowledge at this most fundamental level?
References
There are two good articles written by Dr Leonard Sax that pull together all the relevant research:
http://www.education.com/reference/article/Ref_Boys_Girls/
http://www.singlesexschools.org/research-brain.htm
Academic references
Rhoshel K. Lenroot, et al. Sexual dimorphism of brain developmental trajectories during childhood and adolescence.
NeuroI mage 36 (2007) 1065-1073
Harriet Hanlon, Robert Thatcher, and Marvin Cline. Gender differences in the development of EEG coherence in normal children. Developmental Neuropsychology, 16(3):479-506, 1999.
Killgor, W.D. & Yrgelun-Todd, D.A. Sex-related developmental differences in the lateralized activation of the prefrontal cortex and amygdala during perception of facial effect.
Perceptual and Motor Skills Journal, Vol: 99, 2004 and Cerebral Cortex, Vol. 11, No. 6, 552-557, June 2001 ©right; 2001 Oxford University Press
Michael D. De Bellis et al. Sex Differences in Brain Maturation during Childhood and Adolescence. Cerebral Cortex, Vol. 11, No. 6, 552-557, June 2001
TopGood Reads
This month's book pick is one that has been out for some time because it fits so well with the research news: The Essential Difference by Simon Baron-Cohen Penguin books 2004.
It is a marvellous summary of the male and female brain differences and how this disparity leads to distinctly different ways of thinking and approaching the world. Cohen puts it this way:
The male brain = systemising
The Female brain = empathising
Systemising
Cohen defines systemising as the drive to analyse, explore and construct a system. "The systemiser intuitively figures out how things work." It's the sort of mind that invents things or builds things; the sort of mind that makes rules and creates order. Is this why men so love ritual and ceremony?
Empathising
Empathising is making sense of an individual's behaviour - having an intuitive understanding of the fluctuation in moods and how this affects social interaction. Cohen speculates that women's superior language skills may be due to their stronger ability to empathise.
The female is therefore more likely to be the social glue of our communities; the male the builder of societal structure.
But how do we know that this is not all down to cultural and social influences? The brain is more pliable than we first thought. We can change our brains and change their pathways. But Cohen's own research proves that that our brains are wired in the womb, so we cannot help but follow our established brain-based traits.
Hormones in the womb and the links to brainsex differences
Cohen has carried out a landmark study in child development that relates to testosterone exposure in the womb. Such research was possible because the mothers had undergone amniocentesis for medical reasons. A little of the fluid that surrounds the foetus in the womb was extracted, enabling Cohen's team to measure the testosterone levels, or T-levels for short. He then followed these children as they developed doing various tests as they grew older.
We know from other brainsex studies that testosterone and various other male hormones direct the foetus to the male physical characteristics. They also push brain development into the male brain pattern. We also know from other studies that some behaviours, such as aggression and dominance, are linked to high T-levels. Low T-levels point to a more gentle approach to life.
Testosterone in the womb links to eye contact
A particularly fascinating result of this research is that Cohen's team found that the more testosterone a child is exposed to in the womb the less able they are to make eye contact aged one year. Generally, the boy foetus is exposed to five times the level of testosterone than a girl.
Testosterone in the womb links to language development and sociability
Further findings from this study prove that T-levels also influence language. The higher the T-levels, the smaller a child's vocabulary at 18 and 24 months. Children aged four with lower T-levels had better language, communication, eye contact and social skills - all signs of better empathizing.
Exposure to higher T-levels equated to lower language skills and a narrower field of interest. Such traits force focus onto one or two things, and the ability to focus an interest is an indicator of in-depth systemising. Good systemising abilities are linked to high testosterone in the womb.
So all this fits perfectly with the brainsex theories. If you are exposed to high levels of testosterone in the womb (and males usually are), your brain will be of the systemising type. Females are usually exposed to very low levels of testosterone, so their brains developed into the empathising type.
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Research news
Left right confusion; getting lost and parking
"Some popular surveys suggest that almost 50 per cent of women cannot tell their left from their right without using some sort of code, like a ring on their finger. I fall within this 50 per cent of directionally challenged females - I just can't tell right from left without looking at my hands. Most men, however, don't seem to suffer from this confusion. They have an instinctive sense of right and left. This classic brain based difference between the sexes is the cause of many arguments between couples, particularly when giving directions in the car. She says: "Go left." And then a few seconds later she will say "Oh no, I meant right...or is it left?" He gets annoyed, they soon become lost and it all ends in tears."
In general, research shows that women's brains are organised with functions on both sides of the brain. Our research feature in Newsletter 1 showed very clearly how both left and right sides or the female brain are involved in verbal processing. Popular belief has the right hand controlled by the left side of the brain; the left hand by the right side of the brain. But what if it's not like that in women, and that left and right are mixed up in the female brain? She has a networked brain, so both sides of her body "feel the same". A man's brain organisation is more focused with distinct functions on one or the other side. As we learned in Newsletter 1, verbal processing for him is a left brain function. So perhaps the left and right and right sides of his body literally "feel" different. This theory has evolved from talking to a lot of men who tell me this is indeed the case - they know what the left side feels like, and that it feels quite different from the right side.
What do you think? We welcome comments and contributions and look forward to moderating lively debate on all related topics.
Sense of Direction
The evidence for the biological factors that play a role in the differences found in men and women's sense of direction is overwhelming. The studies show that in everyday life he does have a better sense of direction for geographical location but she does better with landmarks.
An elegantly simple Canadian study by Deborah Saucier showed dramatic differences between the sexes. Two groups were each divided in half, with equal numbers of males and females in each group. Each individual then had to find an unknown location on campus, using the directions provided. Members of one group were given directions relating to landmarks. The other group was given compass directions.
When women used the compass directions they made many more errors and took substantially longer to get to the target than the males. When men used landmarks they made many more errors and took substantially longer to get to the target than the females.
A brain scan study shows that men and women use different parts of the brain to navigate through a maze. In the study, German researcher Georg Gron rigged up a video game with virtual reality goggles enabling volunteers to find their way out of a maze while simultaneously undergoing an MRI brain scan. The men solved the maze puzzle faster than the women, in line with other findings. But the study also found that men and women use completely different areas of the brain for solving the maze problem. The women used the cerebral cortex, i.e., the thinking bit of the brain; men used the hippocampus, in the limbic area of the brain - a part of the brain that in other animals is hardwired for directional navigation.
We know from research with rats that the hippocampus functions as a cognitive map. When the animal moves in a straight line north to south across a room, the locus of activity in its hippocampus literally moves 'north to south' as well, tracking the animal's movement. The research shows that the hippocampus is pre-wired to function as a dedicated microprocessor for spatial geometry - in males. Female lab animals use the cortex to find their way, the males use the hippocampus. Animals and humans share this difference.
So, perhaps he literally has a compass in his brain and employs a more efficient part of the brain to find his way around. But once she knows the route via the landmark method, she will remember it better than he will and be able to go there again very easily. Women do have a better memory for detail - another well-established sex difference.
When it comes to parking the car, a male brain works by imagining things within a space. His brain makes an unconscious computation matching the size of the parking space with the size of the vehicle. It's automatic and accurate. The average woman has to think about it each time she parks, using her frontal cortex, and her spatial awareness is not quite as accurate either.
There are, of course, some exceptions to this generalisation, and some women - myself included - park as accurately as most men. This is most probably due to having a male-organised brain for some spatial processes.
Once we understand these significant differences in male and female brains, men can try to be more tolerant when she gets lost map reading. It's not that she's stupid; it's just the way her brain is wired. Don't get exasperated; buy her a Sat Nav!
TopGood Reads
Each month, Dr Anne Moir provides a brief book review selected from her extensive reading list. April's Book Of The Month is:
The Sexual Paradox by Susan Pinker Atlantic books, London 2008
This is an excellent and enlightening book focusing on of the more fascinating areas of sex difference: why even the most qualified women don't make it to the top of certain professions.
This topic is a political minefield in the UK, and even more so in the US, where gender difference in the workplace cannot be cited as a reason for sexual inequality in terms of achievement. Several eminent academics have been publicly discredited for even daring to suggest it but Pinker's book sets out to establish a far wider and braver proposition: that the big sex divide found in the work place is down to biology, not prejudice. Surprisingly her book has not been greeted with the furore created by other academic attempts to tackle this political hot potato. This is perhaps due in no small measure to her typically female, non-direct approach but also to her posing an intriguing paradox: the high achieving school girls who fail to live up their early promise versus the school boy failures who succeed spectacularly in the world of work. Why is this, she asks? She successfully answers this question by using enlightening stories, and in doing so outlines the fundamentals of the biological sex differences that help shape the differences in the workplace. Pinker draws on two decades of experience as a child psychologist to illustrate her theory. She tracked down boys who had been referred to her with learning difficulties during their schooling and found a surprising number of these so-called educational failures have gone on to do incredibly well in their jobs and careers. The female stories evolved from Pinker's extensive research into the lives of high achieving women who had walked away from their jobs and careers, either taking jobs of much lower status and pay or quitting the workplace altogether. Weaving their stories with the science of sex differences, she clearly and cleverly illustrates the power of biology in their lives.
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Research news
"I read a tremendous amount of scientific and clinical research papers, books and other materials throughout the course of my average working day and want to give Brainsex Matters Newsletter subscribers regular updates on new research studies and their findings. The article that follows here is remarkable in its unequivocal illustration of the distinctly different ways male and female brains process the exact same information."
Tremendous strides have been made in the last decade in our understanding of the brain. This new technology gives us a way of looking inside the living brain, producing an explosion of new information. Some 95% of everything we know about the internal workings of the human brain has been discovered in the last 10 years.
"The thinking bit" of the brain in men and women is wired up in a different way
One of the most consistent findings in this research is that "the thinking bit" of the brain in men and women is wired up in a different way:
- In general, more bilaterally organised in women; more networked
- In men, it is more laterally organised; more focused
This is one of the most robust findings revealed by the brain scan research. There are now a substantial number of studies that show that men and women's brains are organised in a different way.
The scan below is one of my favourite studies where the difference between men and women is so astonishingly clear.
This scan shows M (the men in the top row of the picture) and F (the women on the bottom row) listening to a John Grisham novel. The coloured areas of the brain indicate brain activity, and it clearly shows that men are using only the left side of the brain; women are using both sides of the brain. Language is organised on both left and right sides of the brain in women but only on the left side in men.
Consequences & Conclusions:
- Women are natural multi-taskers and find it hard to do one thing at a time
- Men work from one box to the next; solve one problem and then move on to the next
- Men think that women go on and on; they go all over the place, never get to the point and talk too much
- Women think men are pedantic, obsessive, single minded...and a bit boring!
Good Reads
Each month, Dr Anne Moir provides a brief book review selected from her extensive reading list. March's Book Of The Month is:
The Female Brain by Louann Brizendine, Bantam Press 2007 ISBN 9780593058077 www.louannbrizendine.com
This is an excellent, well-researched book, written from hands-on experience of treating many girls and women in Dr Brizendine's Women's Mood and Hormone clinic. It's a thorough and accessibly written examination of the female mind, with all its hormonal fluctuations. There is a fascinating breakdown of what happens to the brain during pregnancy. Carrying a child rewires the brain and makes the female much more able to tune in to her new baby. There is also an excellent summary of the female teenager hormonal flood and what is going on in her brain. It certainly helps in understanding all that unpredictable adolescent behaviour! There is a great chapter on the hormonal changes that occur in menopause, with a balanced look at the pros and cons of taking hormone replacement therapy. What really struck me as important is that taking HRT protects the brain from ageing. It keeps the brain in much better shape. All in all, a very valuable book whatever age you are, a good read for men too - it would explain a lot to him about why she can't be like him. Brizendine reckons women are emotional F-1 11s compared to men. They really feel the pain of others in an intense way that he does not. The research also shows that she has a need to bond and to talk things through to bring down her stress levels. He, on the other hand, needs to be alone for his stress levels to normalise. It's why she wants to talk and he wants his privacy and space. Just knowing that will makes any relationship easier - we need to respect this difference and to understand that our responses are different just because that's how our brains are wired.
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