top of page


In the 1960s, a social psychologist at Yale University called Howard Leventhal wanted to see if fear was a good tool for changing people’s behaviour. He decided to run an experiment — on students, of course.

At the time, the University Health Centre was giving out free tetanus vaccinations. Leventhal wondered how he could persuade senior students to get vaccinated. He made two booklets. All the same information — but two different angles. One booklet was neutral, the other used scaremongering. Half of the students received the ‘low-fear’ version which had a dry, dispassionate description of tetanus. The other half got the ‘high-fear’ version, which shared dramatic descriptions of the consequences of not getting a vaccination, complete with pretty scary pictures of urinary catheters and tracheotomy scars.

After reading the booklet the students had to fill out a questionnaire. They all now had a good understanding of what tetanus is. But the real test was whether they would go and get vaccinated.

A month later, only 3% of them had received a vaccination. Leventhal was puzzled. He wondered if he’d messed up somehow. So he had the experiment validated by other academics. They said there had been nothing wrong with his experiment. So Leventhal tried it again. He used the exact same booklets — with only one change. An extra page showing a map of the campus, a circle around the health centre, and its opening hours for vaccinations.

This time, 8 times more students got their tetanus vaccination.

Did that increase come from the scaremongering booklet, or the neutral one? Neither. The split was bang-on 50/50. Fear had made no difference. It was a clear call to action that had changed everything.

So, next time you’re wondering why people aren’t taking the action you’d like them to take, go back and check: is your call to action loud and clear?



Solved is a problem-solving blog for entrepreneurs, creators, and anyone else who uses their brain for a living. 


Some articles are anti-BS action plans to help your business grow. Others are questions that help you crack problems laterally and creatively.

Wanna subscribe? 

Boom. You're subscribed.

bottom of page