Meowing Nuns and Invisible Killers: The Science of "Mass Hysteria"

There aren't many occasions when this image is perfectly in context

Should we blame the government, or blame society...or should we blame the images on TV?
    In August of 2011, riots broke out across London as thousands of people took to the streets and engaged in fighting, looting and wanton damage of property.  Within days, the unbridled aggression had somehow spread to other cities across England and soon the entire nation was gripped in a frenzy of cosmopolitan outbursts. 
    The initial trigger had been the police shooting of London drug dealer Mark Duggan, but within 24 hours it had devolved into city-wide pandemonium...and then country wide.  Five people were killed, hundreds were injured and repairs to the city of London totalled over £200 million. 
    Why were so many people getting involved?  This wasn’t a student protest which got out of hand, nor did all these rioters know Mark Duggan.  It was as if everyone was engaging in mania for the sheer blood-soaked hell of it.   
    At the time, numerous "social experts" were interviewed on national news and started blaming it on something they were calling mass hysteria – the idea that humans will uncontrollably copy each other in large groups, even to the point of going against their normal behaviour.  I was doubtful of this explanation.  It seemed more likely that it was just people exercising their sadism and exorcising their emotional demons. 
    However, as a Scientist, I have to be willing to forego gut-instinct and look at the evidence in detail.  Is there any reason to believe that mass hysteria is a genuine phenomenon?  Were the 2011 riots truly a form of extreme group hypnosis or was it individuals making conscious choices to be aggressive under the protection of crowd-anonymity?   

Angus the Angry Penguin was disappointed the riots didn't spread to Antarctica. He had the perfect disguise.

Welcome to the Twilight Zone
    To begin with, let's look at one of the strangest crime waves in recorded history.  On November 19th 1938, in the quaint English town of Halifax, two women named Gertie Watts and Mary Gledhill arrived at a police station and reported being viciously attacked and cut across the face by a man wielding a razor.  Two days later a woman named Mary Sutcliffe stumbled in with a similar story, this time decorated with deep slashes on her arms.
    By November 29th, six other women had been attacked in similar fashion and a manhunt began.  Knife-crime experts were brought in from Scotland Yard and a reward of no less than £10 was offered to whoever caught the man papers began calling “The Halifax Slasher.”
    It was then, while interviewing the nine young women involved, that Detective Chief Inspector William Salisbury uncovered an unprecedented twist.  The Halifax Slasher never existed.  Each woman had fabricated the attacks and self-inflicted the wounds.  Independently.
    After the first attack, newspapers warned the public to be cautious of a knife-wielding monster and several women all decided to slice themselves in order to imitate the real victims, none of them realising there were no real victims.
    Humans can obviously do very strange things in order to feel part of a group – even a group of attack survivors.  Although nobody wants to be the victim of violence, it would appear that some people want to be part of a community so badly they will engage in self-harm to achieve it. 
    Peculiar for sure, but I don't think it's mass hysteria.  These acts of self-harm could easily be the result of loneliness, mental illness or a prurient desire to take part in social drama.  They were also acts which took place in private, rather than as part of a hysterical group.  Fascinating for sure, but not mass hysteria.  The moral of the story is: when you invesitage spooky things around Halifax, the monster probably isn't real.  

Again, how often do you reckon this image gets used so perfectly?

The High School Terror
    Now let's consider another epidemic - one I myself witnessed in 2005.  On the morning in question, as I approached my high school (the one I attended, not the one I currently teach at) I saw an ambulance parked outside with a girl being carted into the back, oxygen-mask in place.  Things got a bit strange when another ambulance arrived an hour later for a different girl, and then they got frightening when a third and fourth arrived that afternoon. 
    Over the following week, eight or nine girls were hospitalised in similar fashion and people were beginning to suspect something like a chemical leak in the Science department.  What was the origin of this mysterious illness? 
    By doing a bit of our own investigating, my friends and I we were able to get to the bottom of the whole thing and we discovered that every pupil was returning to school the following day with an identical diagnosis: they had each had an anxiety attack. 
    To be absolutely clear, anxiety attacks are a genuine ailment and should always be taken seriously.  It's not just people getting worked-up (as I've heard them described).  They are unpleasant and traumatic experiences for the sufferer and it's no wonder ambulances were being called.  Hyperventilation, chest pains, dizzyness, fainting and sometimes even vomiting, were symptoms all the girls displayed.  What made them particularly intriguing was their timeline.   
    Each sufferer had been present at the attack of the previous victim.  The first girl - patient zero - had suffered an attack for some unknown reason and then, seeing the disturbing effects, the second girl became anxious herself.  The third girl suffered a similar fate, as did the fourth and so on. 
    This story is relevant although sadly anecdotal (you’ll have to trust me that it happened), but it still doesn’t quite prove mass hysteria.  Anxiety attacks can obviously be triggered by stressful situations and watching your friend get stuck in an ambulance is clearly a stressful situation.  So, while it was happening to a mass, there may have been nothing hysterical going on.  Who wouldn't get a little anxious after seeing a close friend suffering?  And who wouldn't get even more worked up when other people started showing the same signs of illness?  This could have been friends sympathising with each other in that telepathic way they often seem to do.  

Come to think of it, there were a few other similarities between the students involved...

The cheerful part of the blog
    In November 1978 a community of socialist idealists living in Guyana, under the leadership of the reverend Jim Jones, apparently committed group suicide by drinking grape Flavour-Aid laced with cyanide.  Over 900 people drank from the poisoned chalice including large numbers of children.  All killed in under an hour.  Today this event is referred to as "The Jonestown Massacre". 
    This does sound like a genuine case of mass hysteria at first, but although it’s certainly weird, I’m still not sure it counts.  For starters, Jonestown was a radical political settlement populated by people who had fled their ordinary lives to dwell in huts as part of a socialist order they believed was inspired by God.  It seems reasonable to suggest there may have been a high proportion of extremist/unstable people in the community to begin with. 
    Furthermore, Jim Jones made a tape recording of the entire process and it’s clear that huge numbers of people either objected to what was happening but were violently coerced, or simply didn’t realise they were about to die.  Jim Jones would run pretend-apocalypse drills regularly, so a lot of the victims probably thought it was an act and simply played along. 
    Further-furthermore, Jones had just announced to the entire village that capitalist soldiers would soon be parachuting into their community to kill or kidnap everyone, including the defenceless children.  He suggested it would be better to die free as a sign of protest, than to live as a prisoner.  It's possible that a lot of people in Jonestown were killing themselves out of political and religious ideology.  
    While grim and extreme, lots of people are prepared to die or even kill for their principles and many parents would rather let their children go peacefully if the alternative is imprisonment and torture at the hands of a totalitarian government.
    Jonestown wasn’t a group of perfectly stable people all suddenly doing something hysterical because everyone else was.  This was a village of strong-willed, politicised people with religious convictions of salvation, engaging in a powerful act of defiance, or simply being tricked, threatened and murdered.  In other news, I’ll be writing a children’s book about magical ponies over the Summer.

Not a picture of Jim Jones

The bit where I am proven wrong...
    There are numerous documented cases throughout history of fainting epidemics, outbreaks of dizziness, fevers, seizures, headaches and vomiting, although as we've said, many of these episodes could be the result of anxiety or contageous disease. 
    In order to confirm whether mass hysteria truly occurs we need examples of humans doing utterly uncharacteristic things for no political, religious or social reason other than “everyone else was doing it”.  And, to my great surprise, it turns out there are a few incidents which fit the bill.  
    The doctor JFC Hecker, in 1844, recorded an outbreak  of “meowing” which took place in a medieval French convent.  The nuns in question apparently began making cat noises uncontrollably one evening and were unable to stop for several hours.   
     Then, there was the dancing epidemic of July 1518 in which over 400 people began dancing in the streets of Strasbourg, including the sick and elderly.  Many died from exhaustion in that one, so I guess you could call that...dance fever!  Look, if you don't like my jokes then go back and read the depressing section on Jonestown again.  Stop judging me. 
    Speaking of inappopriate laughter, consider the giggling epidemic of 1962 in which students from Tanganyika began laughing at school and were unable to stop themselves.  That particular epidemic went on for weeks and spread to over a thousand students and teachers at fourteen different schools.
    The sheer number of people involved in these instances makes mental illness an unlikely explanation.  It’s also not an example of “unleashing the beast” unless that beast is a cat who likes dancing and giggling a lot.  Nor were these protests or acts of political and religious defiance.  There is simply no reason to engage in these activities other than imitation so I hereby change my mind.  It would appear that mass hysteria may be a genuine, although rare, phenomenon.

That bit at the end where you go limp and collapse on the ground was really well executed!

So, what causes it?  This is gonna get uncomfortable...
    In Science you always follow the evidence wherever it leads, even if it takes you to an uncomfortable place.  Having decided that I was wrong about mass hysteria, what I really wanted to do was try and find some potential explanation for what causes it and, as I looked into all the recorded historical accounts, I did notice a rather inconvenient theme.  You're probably not going to like this, but trust me, neither do I.
    It turns out that when mass hysteria occurs, the people engaged in the weird behaviour are more likely to be female than male. 
    This is a really unfortunate thing to have noticed because it will give fuel to people who are going to say things like "women are more hysterical" or some such nonsense.  Please bare with me on this.  I'm not about to mansplain why women are naturally more emotionally fragile or something like that.  I think there is something interesting going on here, but it's quite subtle.  Give me a chance. 
    Also, please don't get angry at me for something nature has chosen.  I'm just reporting what appears to be biologically true.  If there is any misogyny here then it's to be found in the architecture of the human brain, not in my describing it.

This better be good...
    The meowing epidemic took place in a convent.  The giggling epidemic affected girl’s schools and mostly female teachers.  The dancing fever was reportedly seen to affect women more than men and the pseudo-mass hysteria cases like the Halifax Slasher or the anxiety epidemic from my own school again centred around young women.  Why? 
    Here's something which I think may potentially be to blame. 
    Human beings, like other primates, come equipped with a group of neurons in their frontal cortex called the mirror neuron system (MNS).  These cells begin firing when you watch someone else perform an action...and they make you want to imitate it.  
    Suppose you’re watching a person who’s fairly similar to you in appearance or personality.  Your brain recognises them as a kind of mirror image so when they do something you imagine yourself doing it too.  If that person twitches their left arm, your MNS sees the movement and immediately wants to copy it.  
    If you’ve ever found yourself yawning because you’ve seen someone else doing it, the reason (proposed by a 2013 study by Helene Haker) may be the MNS.  The same mechanism might also explain why you’re more likely to laugh at a joke when you are in a crowd of people laughing together than when you are on your own.
    It’s even been suggested that these neurons may form the basis of empathy itself.  The MNS in monkeys will trigger a pain-response when they see another monkey being hurt.  This “sympathy pain” felt by the observer monkey looks identical on a brain scan to when the monkey itself is the victim. 
    There’s a clear reason for why the brain developed such a mutation – imitation is crucial to learning.   A brain which repeats what it sees is a brain which picks up skills faster.  We just need to make sure we can override the MNS when it’s not being helpful.  And if you’re wondering how the MNS differs between men and women, the answer is probably what you already suspect.
    Yawei Cheng carried out a study in 2008 which showed people footage of moving objects and found that the MNS response was stronger when the object was a human hand and, more significantly, women showed a greater response than men, particularly when the hand was female.
    It might not be as simple as women having more mirror neurons but it may be the case that women activate the MNS more readily than men, particularly when observing other women.  It sounds like stereotyping but there could be a genuine neurological basis for the belief that women empathise better than men do, particularly with each other.
    Or consider the creepy 2008 story of Identical twin sisters Ursula and Sabina Eriksson who were kicked off their cross-country coach (following unusual behaviour) and left stranded by a motorway.  After disrupting traffic and eventually being stopped by Police, Ursula ran out into the path of a lorry in an apparent escape attempt/suicide.  Sabina then did the same thing.  After seeing her sister get hit, she tried to endure an identical injury for no reason.  And if identical twins aren’t going to have a strong MNS response to each other, I don’t know who would. 

Study the MNS...forever and ever and ever...

A Cautious Hypothesis
    I need to be very clear and explain that mirror neurons are currently a hotly debated topic in neuroscience and nobody is sure how much is real and how much is speculation.  The neurologist Vilayanur Ramachandran has said "mirror neurons will do for psychology what DNA did for biology."  However, psychologist Gary Marcus has said "mirror neurons are the most oversold idea in psychology".  Everything's up in the air right now, which is extremely cool.  It means all bets are on and we've got some learning ahead.
    I'm not a neuroscientist at all (not even a Biologist) so I have to be very clear that a lot of what I'm saying is based on guesswork, potentially poor-quality guesswork.  I have no idea if the MNS can really do what I'm proposing, but that's half the fun of Science...coming up with ideas that may or may not be true!  My hypothesis to explain mass hysteria is therefore as follows:

    Suppose there was a group of women living together/spending time with each other for an extended period, developing a strong MNS response to each other.  Most of the time the conscious brain would be able to override the copycat-instinct but if the environment became stressful or tiring, the brain could get tired, making it harder to suppress that urge.
    If one woman began laughing uncontrollably due to stress, another might join in.  Two could become three, three could become four and pretty soon everyone in the room is howling in unison.  The mirror neurons don’t realise anything strange is happening, so they just force you to keep going, holding you hostage to your own behaviour.
    It’s possible mass hysteria may simply be an exaggerated by-product of women’s superior empathy skills, which in turn could be a result of superior MNS activity.  Put a lot of humans together in a setting which will encourage stress and things are going to get weird. 
    So, if you’re female and under a lot of stress, you really might be able to blame your actions partly on mass-hysteria.  It’s possible you didn’t have complete control over what you were doing at the time.  If, on the other hand, you’re a man smashing a shop window to steal a television as part of a riot then there’s a simpler explanation: you’re a jackass.

Image credits
Cat Nuns: pinimg
Penguins: christianfaithatwork
Scooby Doo: themill
Village of the Damned: horrorhomework
Twilight Sparkle: Mylittlewiki
Dancing with the Stars: tv-fanatic
Awkward: memegenerator
Shining Twins: express