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A New Zealand sociologist says social networking websites can lead to mass global hysteria similar to the scale that took hold of Salem in Massachusetts, in the late 1600's where 20 people were hanged during the infamous witch trials.
Auckland researcher Robert Bartholomew has warned a recent surge in hysteria that now spreads through social media websites, could take hold globally and cause social and economic harm.
He pointed to an incident in January, coincidentally in that same Salem, now called Danvers, in which about two dozen teenagers at the Essex Agricultural and Technical School began having mysterious hiccups and tics.
Dr Bartholomew told The Atlantic.com website there had been a sudden upsurge of those types of outbreaks over the past few years.
It started with conversion disorder, when psychological stressors, such as trauma or anxiety, manifested in physical symptoms, he told the website.
The symptoms become "contagious" due to a phenomenon called mass psychogenic illness (MPI), historically known as "mass hysteria" because people unconsciously believe they've been exposed to the same harmful toxin, then experience the same symptoms.
"(There was) potential for a far greater or global episode, unless we quickly understand how social media is, for the first time, acting as the primary vector or agent of spread for conversion disorder," Dr Bartholomew said.
Epidemics spread by social media were inevitable and it was "just a matter of time before we see outbreaks that are not just confined to a single school or factory or even region, but covering a disperse geographical area and causing real social and economic harm", he said.
Typically teenage girls or young women were susceptible to the phenomenon, but it was not yet known why, Dr Bartholomew said.
Conflict for adolescent girls could be "very sordid" he said.
"With some of these girls, it gets really nasty, and (unlike boys), girls hold it in.
"In the past, you have a problem with another girl at school or a group of girls, you go home, you might make a phone call. Now, you're talking to a whole bunch of people at once. You brood and internalise it more deeply."
In his paper Mass Psychogenic Illness and the Social Network: is it changing the pattern of outbreaks? Dr Bartholomew wrote: "Local priests, who were inevitably summoned to exorcise the 'demons', faced a daunting task given the widespread belief in witchcraft, but they were fortunate in one regard: they did not have to contend with mobile phones, Twitter and Facebook."