Social Epidemics Spread Only When Messages Are Both Contagious and Sticky

Trends, memes, and fads don’t just happen—they catch fire only when the idea or behavior is both easy to pass on (contagious) and refuses to leave people’s minds (sticky). Take the classic example of a TV show introducing a silly, catchy phrase—suddenly, half the school echoes it in the hallways. It wasn’t just the reach of television, but the stickiness that made kids keep repeating and sharing it, turning a quirky line into a badge of in-group identity.

Simulation models of epidemics show that even highly contagious ideas fail to tip if they vanish from memory too quickly. By contrast, concepts that stick—through humor, repetition, or emotional resonance—get picked up, internalized, and, crucially, retold. The difference between a campaign that fizzles and one that becomes a movement often comes down to marrying reach with resonance: the virus with the memorable hook.

Behavioral scientists highlight that, to tip, you need both deep (sticky) and wide (contagious) impact—a combination that might sound challenging, but can be engineered with a little creative effort and feedback from your community.

If you want a positive action or idea to catch on, identify both what makes it worth sharing and how you’ll make it unforgettable—a phrase, symbol, chant, or prize. Build these into your message and trial it with a friend or group. Compare recall and participation in a day or two. This dual approach will increase your chances of turning a good idea into a lasting social ripple. Now’s the time to craft your hook and test it out.