Harvard Mental Health Letter

The psychology of risk perception

Understanding why certain perils seem more perilous than others.

Two environmental accidents in different parts of the world — along with media and public reaction to them — have dramatically illustrated some of the basic psychological principles of risk perception. In 2010, the Deepwater Horizon oil spill sent millions of gallons of oil into the Gulf of Mexico. In 2011, the Fukushima Daiichi nuclear power plant in Japan — damaged after a devastating earthquake and tsunami — leaked radiation into the atmosphere.

These incidents dominated news coverage for weeks and created widespread anxiety, even in people living miles away and not directly affected. For example, news that potassium iodide pills could help prevent radiation-induced thyroid cancer sparked a run on pharmacy supplies in the United States, thousands of miles away from the disaster, even when there was no evidence of increased radiation exposure.

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