The Social Contagion Theory is a concept in psychology that explains how behaviors, emotions, and ideas spread among people within social networks. This theory suggests that individuals are influenced by the behavior of others in their immediate social circle, and these behaviors can spread rapidly through a population.

What Causes Social Contagion?

There are several factors that contribute to social contagion. One important factor is the need to conform to social norms. People tend to conform to the behavior of those around them, especially when they perceive it as normal or desirable.

Another factor is the influence of opinion leaders. Opinion leaders are people who have a strong influence on others within their social network. They may be seen as experts or authorities on a particular topic, and their opinions can sway others to adopt similar beliefs or behaviors.

Finally, technology has played an important role in increasing the speed and reach of social contagion. Social media platforms like Facebook and Twitter allow information to spread rapidly through large networks of people.

Examples of Social Contagion

One well-known example of social contagion is the “Ice Bucket Challenge” that went viral on social media in 2014. The challenge involved pouring a bucket of ice water over one’s head and challenging others to do the same or donate money to support research on ALS (amyotrophic lateral sclerosis). Within weeks, millions of people had participated in the challenge, raising over $100 million for ALS research.

Another example is the spread of “fake news” during the 2016 U.S. presidential election. False stories about candidates were shared widely on social media platforms, influencing public opinion and potentially affecting election outcomes.

The Negative Effects of Social Contagion

While social contagion can have positive effects, such as raising awareness for important causes, it can also have negative consequences. For example, it can lead to groupthink, where individuals conform to the beliefs of the group without critically evaluating them. This can result in poor decision-making and a lack of creativity.

Social contagion can also lead to the spread of harmful behaviors or ideas, such as hate speech or conspiracy theories. When these behaviors or ideas are accepted as normal within a social network, they can become entrenched and difficult to change.


The Social Contagion Theory helps us understand how behaviors, emotions, and ideas spread through social networks. While it can have positive effects, it is important to be aware of the potential negative consequences and take steps to promote critical thinking and responsible behavior within our social circles.