Years ago, when I was first finding my feet as a psychiatrist, I received a call from a radio station. Something strange had happened at Melbourne airport - a gas leak. Dozens of people had fainted, hazmat teams were on site, and paramedics were treating passengers. Everyone was confused. Most importantly, no one could find any gas. The radio wanted a shrink.
It was 2005. The world still felt tense after 9/11. Air travel was filled with a constant sense of fear. That morning, someone at the domestic terminal reported an unusual smell. Others agreed. Then came dizziness, headaches, nausea—and a wave of fainting and panic. Fifty-seven people were affected. Forty-seven were taken to hospital. The terminal shut down.
Tests found nothing. No chemicals. No airborne toxins. No malfunctioning vending machine pumping out toxic Big M.
What they ultimately concluded—and what I, in my very first moment of public commentary, tried to explain on air—was that this was a typical case of mass psychogenic illness. A psychological chain reaction: one person's anxiety triggering another’s until the whole terminal tipped into panic.
I’ve never forgotten that incident. And lately, I’ve been thinking about it again—because it turns out that contagion, once the domain of viruses and gas leak rumours, now spreads in new places. Like your phone.
What Is Social Contagion?
Social contagion is how behaviours, emotions, and beliefs spread among people. Not through direct instruction, but through imitation, absorption, and vibe.
There are three main types:
- Behavioural contagion—we copy what people do (especially if we envy them)
- Emotional contagion—we soak up other people’s moods like sponge cake in a trifle
- Informational contagion—we adopt ideas because others around us believe them
And the reach is impressive. Science says it extends across three degrees of separation. This means your best mate’s cousin’s gym instructor could be influencing your opinions on politics, sunglasses, or an almond latte.
Social Media: Contagion on Steroids
What once happened slowly and locally now occurs instantly and worldwide. Voilà: social media.
On platforms like Instagram, TikTok, and X (formerly Twitter, formerly tolerable), ideas spread like wildfire through dry grass. A laugh here, a wellness trend there, and suddenly your entire feed is doing ice baths and planking.
And it’s not just researchers noticing. Recently, media coverage has increased, highlighting how social contagion influences everything from misinformation to moral outrage. The articles introduced the term “complex contagion”—the idea that certain behaviours or beliefs need reinforcement from multiple sources before they take hold. It’s not one post that influences you; it’s the fifth one that feels eerily aligned with your mood at 11:48pm.
They also flagged a promising new technique called “pre-bunking”—a kind of mental vaccine that teaches you how to recognise manipulation before it happens. Think of it as an emotional condom: not 100% effective, but still worth using.
Some researchers have gone even further, using pandemic models to explain how inequality spreads. Their theory? Social status behaves like a virus, clustering in tight networks and being passed on through contact. Hang around opportunity, and it might rub off. Stay surrounded by disadvantage, and it sticks.
Walking While Infected
Next time you're walking down the street, try this: look up. You’ll see dozens of people—young, old, corporate, barefoot—staring blankly at their phones. Not just using them. Being used by them. Algorithm-fed, emotionally-hijacked, doom-scrolling, dopamine-deprived zombies.
It’s not that we’re weak. It’s that our brains are wired to connect with others. We’re social beings. Mimicry helps us learn. But when that mimicry is filtered through ten thousand curated images of panic, rage, or perfection, things get... complicated.
And if you're wondering whether this influences how we vote, protest, or form opinions, the answer is: definitely. The contagious nature of outrage and allegiance now drives entire political campaigns. Anger spreads faster than policy. Tribes form quicker than facts. Social contagion is rapidly becoming democracy’s new engine—or its new virus.
When Contagion Turns Toxic
In hospitals, we've long noticed the effects. Clusters of teenagers self-harming. Tic-like disorders spreading through TikTok. Sudden, sharp increases in certain behaviours that appear like epidemics but are actually echoes.
It’s not about faking. These symptoms are genuine. The pain is real. But how that pain shows up can be contagious.
And it’s not just mental health that spreads; physical behaviours do too. Who remembers RSI (repetitive strain injury) from the 80s and 90s? Obesity, smoking, exercise, and food choices—all influence social networks. If your close mate becomes obese, your own risk goes up by 57%. Not because they’re feeding you doughnuts, but because social norms quietly shift. What's seen as acceptable changes.
But that also means change can work in reverse. Good habits also spread. Hope is just as contagious.
Can We Protect Ourselves?
Yes, but not passively.
Some schools are using peer influence to reduce bullying and suicide. Some platforms (slowly, reluctantly) are flagging dangerous content. And the more you learn about contagion, the better you can resist its pull.
In fact, I suggest we need the psychological version of a Rapid Antigen Test. Forget the RAT—it’s time for the CAT: the Contagion Awareness Test.
A quick three-question tool to see if your latest thought, mood, or opinion is truly yours, or just something you’ve absorbed like secondhand smoke.
The CAT Test:
- Did I believe this faster than I should have?
- Did I feel something before I thought something?
- Would I still believe this if none of my friends did?
If two or more come back positive, isolate your brain. Rehydrate with actual evidence. Avoid close contact with hashtags for 24 hours. Easy. No Q-tip, no gagging, no tears.
Swap the RAT for the CAT. It won’t spare you from scrolling, but it might just save your sanity.
Guilty as Charged
Of course, I’m not above it. I’m literally using literature to spread — meta, I know.
I hope this essay goes viral. Like, share, subscribe — go on, start an outbreak of reason. Wink wink.
One Last Warning
Not every challenging issue should be blamed on social contagion. In 2018, some researchers suggested that teenagers identifying as transgender were doing so because of “Rapid-Onset Gender Dysphoria”—implying it was more of a fad than a fact. That theory was widely criticised for weak science and strong bias. It’s a good reminder: just because something spreads doesn’t mean it’s false. Sometimes, it’s just long-silenced truth finding its voice.
Final Thoughts
That day at the airport revealed how panic can spread without reason. These days, it doesn’t need a rumour about gas; just a few minutes online will do.
We pass emotions like gossip. We inherit opinions like hand-me-downs. We walk around with invisible leashes—tethered to trends, moods, memes.
So next time you feel a wave of anger, inspiration, or a sudden urge to alphabetise your pantry at 2 am, reach for the CAT.
And then ask yourself: Is this mine? Or did I catch it?