What Is Mass Hysteria (Mass Psychosis)?

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At a Glance

Mass hysteria events have occurred throughout history, but they still happen today and are hard to control and even harder to prevent.

Mass hysteria (mass psychosis) is a social phenomenon where a group of people develop similar symptoms that do not have an identifiable physical cause (such as an illness). Instead, the symptoms stem from psychological causes. In mass hysteria events, the symptoms occur in two or more people who also share a common belief about what might cause the illness.

This article will go over what mass hysteria is, what causes it, and examples of mass hysteria.

What Is Mass Hysteria?

Mass hysteria is also called epidemic hysteria, mass psychogenic illness, and mass sociogenic illness. Even though mass hysteria starts in the mind, it can produce real physical symptoms and lead to severe psychological distress.

Several factors are thought to contribute to the phenomenon, including groupthink, stress, and social pressure. Some psychologists believe that mass hysteria is a form of groupthink. In cases of mass hysteria, group members all develop a common fear that can spiral into a panic.

Signs of Mass Hysteria

Mass hysteria occurs in groups of people. Signs of mass hysteria include:

  • Symptoms are relatively benign and include dizziness, muscle twitches, headaches, or stomachaches
  • Symptoms begin and end suddenly
  • Symptoms appear to occur among specific social groups
  • Symptoms have no clear medical explanation after extensive investigation

People may show symptoms after spending time together in a single location, which can lead them to suspect that the symptoms are from a contagious illness or environmental contaminant.

Mass hysteria is difficult to identify as it is happening. In most cases, it is only determined after an investigation and testing reveals there was no underlying illness or cause for the symptoms.

Causes of Mass Hysteria

While the exact causes of mass hysteria are not entirely understood, several factors might play a role.

Mass hysteria often starts with an environmental trigger. For example, imagine that people in a town smell a terrible scent. Then, a few people fall ill with similar symptoms, like a headache and dizziness. Since the people started having symptoms shortly after the bad smell, the rest of the community might assume that the scent is coming from a toxin in the air that's making people sick. Even if the people got sick for an unrelated reason, the timing of their symptoms around an unusual event (a strange smell) may influence what others believe about their illness.

Groupthink

Groupthink is a psychological phenomenon that occurs when a group forms a quick opinion that matches the group consensus rather than critically evaluating the information. Groupthink seems to occur most often when a respected or persuasive leader is present, inspiring members to agree with their opinions.

While it can be positive at times, groupthink is more often seen in a negative light, particularly in the United States and other countries that value individual opinion.

Stress

Experiencing extreme stress or trauma may also play a role in causing mass hysteria. When people are dealing with stressful or overwhelming situations, they may mistakenly attribute feelings related to stress as having a physical or environmental cause. When people are subjected to collective trauma, they may begin to experience psychogenic symptoms.

Social Pressure

Social pressure may also play a part in feeling symptoms related to mass hysteria. When many people are exhibiting similar symptoms, they may either feel consciously or unconsciously pressured to also exhibit those same symptoms.

Fearing that others are sick can make people pay more attention to their bodily sensations, which they might attribute to mass illness. Some reports suggest that social media-induced illnesses, which are a form of mass hysteria, are becoming more common, particularly among teens.

Deindividuation is the idea that being part of a big group can cause us to lose our sense of self and identity, and exhibit behaviors we normally wouldn't. Social pressure is a major component of this phenomenon.

Examples of Mass Hysteria

Mass hysteria events have occurred throughout history. Here are a few examples:

Dancing Plagues

In the Middle Ages, “dancing plagues” spread in Europe. A well-known one was in Strasbourg in 1518. After one woman in town began to dance, hundreds of residents followed her lead and danced for days without stopping—not even to eat or sleep. Some people danced themselves to death.

Witch Trials

Witch trials throughout history, such as the Salem Witch Trials, are prime examples of mass hysteria related to groupthink and extremism. In these instances, people in communities became convinced that individuals were responsible for causing symptoms, illnesses, and other misfortune through the use of witchcraft.

War of the Worlds Radio Broadcast

The panic over the War of the Worlds radio broadcast is another example of mass hysteria related to groupthink.

In 1938, a play by Orson Welles about a Martian invasion of Earth was played nationwide on the radio. People did not realize it was fiction, and soon people panicked because they believed that an alien invasion was taking place.

Tanganyika Laughter Epidemic

In 1962, a student in Tanzania (back then known as Tanganyika), East Africa, started to laugh and cry—and couldn’t stop. Soon, the emotions spread to at least 1,000 people and went on for over a year. Schools even had to close because the students were laughing and crying nonstop for days on end.

9/11 Skin Rashes

Following the 9/11 terrorist attacks, groups of elementary school children reportedly experienced skin rashes, but only when they were at school. The phenomenon was later described as a psychosomatic reaction to collective trauma.

Twitching Disorders

A widely publicized case of possible mass hysteria occurred in 2011 in upstate New York when teenage girls from the same high school developed an unexplained twitching disorder.

They were later diagnosed with conversion disorder, but the diagnosis was met with opposition and anger from parents and the affected students.

An article published in American Ethnologist criticized the diagnosis as well. The article's authors suggested that the mass hysteria diagnosis dismissed the students’ symptoms without adequately investigating environmental factors that could have played a role.

Does Social Media Create Mass Hysteria?

Social media may play a role in perpetuating mass hysteria today. For example, there have been cases of young people developing tic disorders after seeing videos of people with tics on TikTok. However, more research is needed to understand how social media may contribute to mass hysteria.

Effects of Mass Hysteria

While mass hysteria is often a controversial diagnosis, the phenomenon is concerning because it can contribute to other problems, including:

  • Public health problems
  • Missed work or school
  • Financial costs associated with missed work
  • Expenses connected to the attempted removal of non-existent environmental toxins

Mass hysteria can lead people to seek medical treatments they don't need or dubious treatments that could be harmful. It can also create disruptions in people's lives or prompt attempts to remove non-existent poisons or toxins.

Mass hysteria can also cause psychological distress. It can be extremely upsetting to have unexplained symptoms, particularly when no underlying cause can be found. However, it is also essential not to dismiss symptoms as a sign of a mass psychogenic illness without truly looking for an environmental or pathogenic cause.

Some researchers have suggested that collective mass hysteria may have led to consequences during the COVID-19 pandemic, particularly as misinformation spread through social networks and influenced public health and health-related behavior. 

How to Reduce Mass Hysteria

Mass hysteria needs to be treated as a serious potential public health issue. The source of the symptoms must be investigated, and people need to be treated for their unexplained symptoms.

There are a few tactics that can help people avoid getting caught up in mass hysteria:

  • Separation: Separating people showing unusual or unexplained symptoms from the general public can help prevent their behavior from influencing others.
  • Stress reduction techniques: Stress management strategies such as deep breathingmeditation, visualization, or progressive muscle relaxation might help people who are distressed by unexplained symptoms that they or others are experiencing.
  • Psychotherapy: Talking to a therapist can be helpful for people experiencing or witnessing mass hysteria. Therapeutic approaches such as cognitive behavioral therapy (CBT) can reduce negative or anxious thoughts that contribute to mass hysteria.

Summary

Mass hysteria can become a public health problem and has had serious consequences throughout history. It is usually noticed only in retrospect, which makes it difficult to stop once it has started.

While unexplained symptoms should not be written off as mass hysteria without an adequate search for a cause, it’s important to give panicked people resources for coping and implement strategies to prevent the spread of mass hysteria. 

15 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading
  • Janis, I. Groupthink: The Desperate Drive for Consensus at Any Cost In: Shafritz, J. Ed. Classics of Organization Theory. Chapter 15, 2015.

  • Janis, I. Victims of groupthink: A psychological study of foreign-policy decisions and fiascoes. Houghton Mifflin. 1972.

By Lisa Fritscher
Lisa Fritscher is a freelance writer and editor with a deep interest in phobias and other mental health topics.