People have trouble understanding probabilistic information about unfamiliar activities and technologies.

In addition, cognitive biases hamper people’s understanding of probabilities. This difficulty, in turn, hampers discussions of risk probabilities between experts and nonexperts.

For example, the public will often reject the argument that a cancer risk from a new activity is acceptable if it is smaller than one in a million.

This is frustrating for risk communicators because a one-in-a-million risk is an extremely small number.

Why Do People Reject Arguments by Experts?

When people reject arguments by experts, they usually do so with one or more of the following objections:


People often personalize the risk. A person might ask: What if I am the person who is harmed?


People often raise questions of trust. A person might ask: Why should I believe you? Haven’t you made mistakes or changed your mind about risks in the past?

Cumulative Risks

People often raise concerns about cumulative risks. A person might ask: If I am already exposed to enough risks in life, why do I need to take on even one more?


People often question whether the risks are worth the benefits. A person might ask: Is the activity that generates the risk really worth compromising one’s health or life?


People often raise ethical questions. A person might ask: Who gave you the right to play God and choose who will live or die?

Further Problems Affecting Discussions

Exacerbating the problem is the difficulty people have understanding, appreciating, and interpreting small probabilities, such as the difference between one chance in 100,000 and one chance in 1,000,000.

These same problems hamper discussions between technical experts and nonexperts on low-probability events, high-consequences events, and worst case scenarios.

In many such cases, the ability to imagine the worst case makes it difficult for people to distinguish between what is remotely possible and what is probable.

Given these difficulties, to be effective, risk communication strategies must address the experiences, attitudes, beliefs, values, and culture of message recipients and message senders.

Remember: Effective risk communication skills are built on a foundation of understanding how people perceive risks.

Pathway Prompt: What are issues you’ve seen when experts try to communicate information to nonexperts? How could these have been resolved?

Communicating Effectively When Feelings, Fears, and Facts Collide

More information about risk, high-concern, and crisis communication can be found in Dr. Covello’s video-based course Pathway to Risk, High-Concern, and Crisis Communication.

This master class introduces communicators to the tools and techniques for communicating effectively—while providing greater insight into why audiences react the way they do during times of stress.

The course comprises nine video lectures and accompanying text modules, plus supplemental materials for putting valuable lessons into practice. More information about the course, including group rates and partnering opportunities, can be found by emailing

Dr. Vincent Covello

Dr. Vincent Covello, director of the Center for Risk Communication, is one of the world’s leading experts and practitioners on risk, high-concern, and crisis communication. He is the author of more than 150 articles in scientific journals and the author/editor of more than 20 books.