From laughter to loneliness
When something is contagious, it means it’s transmissible and it can spread from one person to another. We often associate this with diseases, but many other things can be—and indeed are—contagious. We’re talking about sensations, emotional states, behaviors, and actions.
In this gallery, we bring you a number of things you may not know are contagious:
- Feeling cold - Temperature contagion is a thing. Research conducted at the University of Sussex in the UK found that just looking at someone who is cold will make our own body temperature drop.
- Loneliness - A large-scale study, which considered data for more than 60 years, found that lonely people often share their loneliness with other people. These people, in turn, start to feel lonely as well.
- Laughter - Laughing is definitely contagious. According to psychologist Robert Provine, “you're 30 times more likely to laugh with other people than you are on your own.”
- Yawning - Raise your hand if you yawn when you see someone else doing it! This behavior can even occur when we hear, or even read, about someone yawning.
- Noncommunicable diseases - Noncommunicable diseases (NCDs) are conditions that are usually not caused by an acute infection and that can't be transmitted between people. NCDs are believed to be caused by a mix of genetics, environmental factors, and lifestyle choices. Examples include heart disease, diabetes, cancer, and obesity.
- Restaurant orders - A study conducted by the University of Illinois found that diners tend to order foods that are similar to those of their companions. “Diners wanted to be different from their dining companions, but not too different."
- Divorce - A 2013 study found that people who were friends with divorcees were 75% more likely to get a divorce than those whose friends were still married.
- Goals - Another person's behavior, especially in our inner circles, can affect ours. How many times has someone left a party early and you found yourself looking at the watch, too? The same applies with goals.
- Happiness - Many of us have experienced this when we are around positive, upbeat people, right? It turns out, this positive influence spreads even further around us. “Even people we don’t know and have never met have a bigger effect on our mood than substantial increases in income.”
- Cancer - Cancer is a noncommunicable disease, but there are animals that can actually spread cancer to each other, namely Tasmanian devils, soft-shelled clams, and dogs. While the transmission of cancerous cells between humans is not believed to occur under the same circumstances, there are cases where this is believed to have occurred.
- Itching - It’s safe to say that most of us have felt our own skin tingling after we’ve seen someone scratch an itch. This happens all the time, and it’s not only limited to humans. Experiments with rats have reached similar conclusions.
- Bad behavior - A theory known as the broken windows theory suggests that signs of crime, anti-social behavior, and civil disorder trigger more of the same behavior, thus spreading it.
- High blood pressure - Researchers found that mice infected with cytomegalovirus (CMV) developed higher blood pressure than those without the virus. CMV altered their behavior and caused them to eat more high-cholesterol foods. And, it turns out, trials with human cell cultures had similar results.
- Desire for new things - We tend to rate objects as more valuable when other people want them. Though the “wedding-band syndrome,” as psychologist Elizabeth Lombardo calls it, is also applicable to people. “A man is more attractive if someone already wants him—he must be worth having,” she explained.
- Stomach ulcers - Stomach ulcers are mainly caused by a bacterium called Helicobacter pylori, which is carried by a large percentage of the world’s population. While many people don’t experience any symptoms, others may develop peptic ulcers in the stomach and small intestine.
- Stress - When we detect signs of stress in other people, our bodies release stress hormones. And this doesn’t even need to occur in person. This stress response can be triggered by an email, a text, or social media, for example.
- Negative thinking - According to a study by the University of Notre Dame, you can “catch” negative thinking if exposed to it. The study randomly paired freshmen with roommates who were highly prone to brooding. The freshmen “caught” their negative-thinking style after three months.
- Cavities - Kissing someone with poor dental hygiene may not be good for your oral health. This is because cavity-causing bacteria may end up in your mouth.
