Catherine Sanderson, Amherst College – Bystander Effect

On Amherst College Week: Why is the bystander effect so prevalent?

Catherine Sanderson, professor of psychology, explains it all starts in the deep within the brain.

Catherine Sanderson is the Manwell Family Professor of Life Sciences (Psychology) at Amherst College. She received a bachelor’s degree in psychology, with a specialization in Health and Development, from Stanford University, and received both masters and doctoral degrees in psychology from Princeton University.  Professor Sanderson’s research examines how personality and social variables influence health-related behaviors such as safer sex and disordered eating, the development of persuasive messages and interventions to prevent unhealthy behavior, and the predictors of relationship satisfaction. This research has received grant funding from the National Science Foundation and the National Institute of Health. Professor Sanderson has published over 25 journal articles and book chapters in addition to four college textbooks, a high school health textbook, and a popular press book on parenting.  In 2012, she was named one of the country’s top 300 professors by the Princeton Review.

Bystander Effect


We are bombarded daily with news reports of bad behavior, from sexual harassment in the workplace to racist attacks on public transportation to bullying in schools. Although it’s easy to blame these acts on “evil” people, it’s far more complicated to understand why so many bystanders fail to speak up, and what role silence plays in perpetuating the behavior itself.

I write about the psychological factors that lead most of us to hold our tongues in such situations. It starts at a molecular level: Cutting edge research shows that that pain caused by social elements—such as being ostracized by people in our community—triggers a similar neurological response in the brain as physical pain. Conforming feels good, in other words, and deviating does not. 

This biological reaction has other implications, studies have found. Bystanders believe that speaking out may pose risks to personal safety or career advancement, to name two. Even in cases in which speaking out doesn’t directly impact one’s life or career, the perceived social costs of calling out bad behavior can be substantial. We fear looking foolish and feeling embarrassed, and being ostracized from social groups. Such costs are what lead fraternity brothers to stay silent while watching hazing rituals, colleagues to laugh at offensive remarks, and leaders in the Catholic church to protect abusers instead of children. 

Better understanding the natural human tendencies to avoid confronting bad behavior can help overcome the factors that lead to silence and inaction. We can then work to reduce bad behavior, locally and globally. As Martin Luther King Jr. said, “History will have to record that the greatest tragedy of this period of social transition was not the strident clamor of the bad people, but the appalling silence of the good people.” 


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