The Original Pokémon Menace

Largely forgotten today, a panic over mysterious Pokémon-related illnesses scared much of the world and puzzled doctors 20 years ago.

Only those living under a rock or on a self-imposed news and social media quarantine could fail to have heard about the latest fad sweeping the world: Pokémon Go. The game app uses geolocation features that allow users to view a virtual Pokémon-populated virtual world through their phone's camera. The goal is to "capture" the digital creatures ("Gotta catch 'em all" is the game's slogan) and use them to train and battle for virtual territory.

The game has become enormously popular, with millions of people around the world playing the game since its July 6 launch. It's been credited with getting slothful video game players out for fresh air and exercise-and even sparking romance.

While for most it's harmless fun, reports have emerged of various pickles that Pokémon players face, and in a recent Seeker piece Aylssa Danigelis listed ten hazards of virtual reality gaming, including trespassing arrests, car crashes, falling or tripping due to inattention, and robberies.

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An article in "The New York Times" offered the ominous headline "Nations of the World Confront the Pokémon Menace," warning that "In Saudi Arabia, clerics renewed an existing fatwa against Pokémon, calling it 'un-Islamic.' Bosnia has warned players to avoid chasing the creatures onto land mines left over from the 1990s [and] Russian websites published articles claiming the game is a C.I.A. plot, while religious figures denounced it. 'It smacks of Satanism,' a Cossack leader told local media."

If all this concern over Pokémon Go sounds a bit over-the-top, it's not the first time. Though many current Pokémon fans are likely too young to remember it, nearly 20 years ago there was a very different kind of panic and hysteria surrounding the cartoon upon which the game is based.

The Pokémon Panic

In 1997, according to news reports up to 12,000 Japanese children reported illnesses ranging from nausea to seizures after watching an episode of "Pokémon." On the night of December 16, Pokémon episode "Dennou Senshi Porigon" aired in Japan at 6:30. The program was broadcast over dozens of TV stations, had an audience of millions, and held the highest ratings for its time slot.

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About 20 minutes into the cartoon, flashing lights filled the screens when the Pikachu character used his electricity powers during a battle scene. By 7:30, according to news reports, 618 children had been taken to hospitals complaining of sudden symptoms including labored breathing, fainting, and headaches.

The story of thousands of people-mostly children-being made sick by their favorite cartoon raced through Japan and around the world. The television station apologized and immediately pulled all future Pokémon episodes from its programming. Although Nintendo, the game's creator, immediately issued a statement explaining that the only link between its game and the cartoon was the characters, the company's stock plummeted on the Tokyo stock market.

TV Tokyo put warning labels on all future and past Pokémon episodes. Despite the global panic-and unanswered questions about what happened-audiences missed the show and it was back on the air by April. Still, doctors and epidemiologists in Japan and around the world struggled to explain the bizarre incident. Never before in history had so many people been afflicted with seizures at one time in a single incident. It was unprecedented-and unexplained.

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The bizarre episode was later parodied on "The Simpsons" in an episode featuring the fictional Japanese show "Battling Seizure Robots." In it, Homer sees his family on the floor having seizures induced by the TV show and gamely joins them, throwing himself on the floor and rolling around in the family activity.

The fact that bright flashing lights can trigger seizures in people with photosensitive epilepsy (PSE) is well known in the medical community. PSE seizures can occur when the sun is seen from a moving car through tree branches, for example, causing a strobe effect. Many commercially sold strobe lights and video games come with seizure warnings, and concert venues often warn audiences that flashing lights may be part of a show. There seems little doubt that at least some children did in fact experience seizures from watching Pokémon.

But a few experts suggested that mass hysteria might somehow have played a role. Mass hysteria is often misunderstood as being an illness that sufferers are making up. In fact the symptoms are not imaginary. The issue is instead what is causing the symptoms-whether some external environmental contaminant or instead a form of suggestion-driven social contagion.

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Humans are social animals and we often take our cues from others, both consciously and unconsciously. People can unconsciously mimic the actions and reactions of their peers; if one or more of them start to faint or feel sick in their presence it can create a domino effect, spreading to others. Symptoms of mass hysteria are typically minor (fainting, nausea, and headaches) and brief (most lasting only a few hours or a few days).

I played a key role in solving this mystery; here's how. I'd researched mass hysteria and in reviewing journal articles and news reports I discovered that many of the symptoms reported in the Pokémon case (such as headaches, dizziness, and vomiting) are in fact atypical of PSE seizures, whose classical symptoms include drooling, stiffness, and tongue biting. There is some variation, but the overall trend was unmistakable: the symptoms clearly pointed away from PSE and instead toward mass hysteria.

Furthermore the incidence of photosensitive epilepsy is estimated to be about 0.02% of the population. Unless the incidence of PSE in the Japanese population is exponentially greater than is known, the epilepsy-induced seizures could not account for the sheer number of Pokémon victims (in some cases nearly 7 percent of the viewers).

Solving the Mystery

While several important aspects of the Pokémon panic indicated that it was a case of mass hysteria (also known as mass sociogenic illness) there was one insurmountable problem with that theory: Most of the afflicted children were in their own homes. Mass hysteria occurs in groups (usually dozens or hundreds). Since the children who had seizures in front of the television could only have influenced others in the room, there seemed to be no way that thousands of kids could have independently been afflicted. With no mechanism for contagion to spread, it couldn't be mass hysteria-but no other explanation was more plausible.

The solution to the mystery lay in the timeline: the Pokémon mystery illness didn't happen, as many had assumed, all at once during one cartoon broadcast but instead unfolded over the course of several days. The number of children reported to have been affected is around 700 the evening of the Pokémon episode.

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However news of the mystery illnesses dominated Japan's news media the following day, and any students who hadn't heard about the scary news from their concerned parents or on the news certainly heard about it from their friends at school-and schools are among the most common places for mass hysteria outbreaks to occur. Once that happened, the number of kids reported to have been afflicted by the cartoon-two days earlier-skyrocketed to 12,000. The news media likely exaggerated the numbers, which created even more concern, and the panic snowballed.

In the final analysis, there were a handful of people out of the millions of viewers-perhaps a few dozen or even a few hundred-who did have PSE-related seizures triggered by the flashing lights on the Pokémon TV show. But the vast majority of those thought to be afflicted were actually suffering from a different (and often unrecognized) illness: mass hysteria.

They began exhibiting and mimicking symptoms based not on viewing the cartoon itself but their friends and peer's reactions to it. My research on the case, co-authored by sociologist Robert Bartholomew, was published in the February 2001 issue of "The Southern Medical Journal."

The full risks of Pokémon Go remain to be seen, but the original Pokémon panic remained a medical mystery for many years and a bizarre footnote in the history of television and gaming.