You want to persuade your team members to provide ideas or feedback, so you write an email to one person, with everyone else’s name in the “cc” box. You get no response and wonder why your persuasive appeal failed.

The problem is that when multiple individuals are aware that others also are responsible for acting, then it’s more likely that no one will act. Psychologists John Darley and Bibb Latane, writing in the Journal of Personality and Social Psychology, call this an example of diffusion of responsibility. When numerous people are available to take action, the pressure to do so does not fall on any one person.

If you want people in your department to respond to your request, a one-size-fits-all message might not be the best approach.By picking a few people you can rely on and customizing the email messages, you make your appeal specific to each person. Otherwise, when the responsibility for acting is diffused among numerous people, the potential blame for not acting is also diffused. “As a result, no one helps,” Darley and Latane wrote.

It is the reason bystander inaction in emergencies occurs so often, which is what Darley and Latane were studying when they created an experiment in which a person in a group simulated a seizure and received little help from people nearby. Although such a response is often attributed to apathy, Darley and Latane say the explanation “may lie more in the bystander’s response to other observers” than to indifference.

This is another side of the social consensus principle, which says that when people are unsure what to do they let the behavior of others guide them in their decision. You can use that principle to your advantage in some instances, but in other scenarios, the same principle will work differently.