Character  &  Context

The Science of Who We Are and How We Relate
Editors: Mark Leary, Shira Gabriel, Brett Pelham
Jan 27, 2020

My Enemy’s Enemy is My Friend—Common Enemies Blur Lines between Groups in Conflict

by Felicitas Flade
Illustration of a group of superheroes

On a walk during the 1985 Geneva Summit, former U.S. President Ronald Reagan asked Soviet Leader Mikhail Gorbachev whether the Soviet Union would help the United States if it were attacked by aliens from outer space. Gorbachev, while puzzled, agreed that it would, possibly warming up the Cold War a little. Stories like this about adversaries uniting to defeat a shared enemy have endless appeal.

We relate to these stories because they remind us of familiar subplots in which hatchets are buried, old friends reunite, and together, they defeat a shared enemy against all odds. In this case, research confirms our intuition. Since Sherif’s ground-breaking research over 60 years ago, many studies have shown that, in the face of a common enemy, even entire adversarial groups start to like each other more. My colleagues and I wanted to examine why this happens.

Our research showed that uniting against a common enemy changes the way people perceive similarity across racial and gender divides. Specifically, uniting against a common enemy causes profound changes in the degree to which we categorize other people as “us” or “them.”

To study this phenomenon, participants in our experiments saw several speakers’ faces or names along with statements they made.  The discussions were either about neutral topics like daily life or about a common threat like terrorism or disease. The speakers clearly belonged to one of two categories. In some studies, they were either Black or White, in some they were male or female, and in one study they were Jewish or Arabic. Then, participants were asked to remember who said each statement.

We were interested in the kinds of mistakes people made in identifying who made each statement. For example, if one of the Arabic speakers said something, and participants couldn’t remember exactly who said it, would they be more likely to guess that it was one of the other Arab speakers or a Jewish speaker?  If they thought it was another Arab speaker, that would suggest that they were categorizing speakers on the basis of being Arab versus Jewish. 

Participants made fewer mistakes based on skin color and gender when the speakers were discussing a common enemy. In other words, when presented with a common enemy, participants were less likely to see people as Black or White or as Women or Men but maybe just as all human. This effect occurred even for Israeli Jewish and Arab participants who were discussing the Israeli-Palestinian conflict: having a common enemy led them to categorize one another less. In short, people categorize others less into groups when they are threatened by a common enemy.

The effect occurred in the absence of many of the conditions that research suggests are needed to break down boundaries between in-groups versus out-groups.  For example, the speakers did not have to like each other, have a common goal, or even cooperate toward working towards this goal. Moreover, it occurred even when people were not directly threatened by the common enemy.

So, what can we conclude from our research?  When people share a common enemy, we don’t just unite on the surface to face the threat. Sharing a common enemy also changes how people see one another in profound and important ways.

For Further Reading

Flade, F., Klar, Y., & Imhoff, R. (2019). Unite against: A common threat invokes spontaneous decategorization between social categories. Journal of Experimental Social Psychology, 85, 103890.

Sherif, M. (1958). Superordinate goals in the reduction of intergroup conflict. American Journal of Sociology, 63(4), 349–356.


Felicitas Flade is a social psychologist at the University of Mainz, Germany who studies how social groups come to be, persist, and influence our thinking.

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Why is this blog called Character & Context?

Everything that people think, feel, and do is affected by some combination of their personal characteristics and features of the social context they are in at the time. Character & Context explores the latest insights about human behavior from research in personality and social psychology, the scientific field that studies the causes of everyday behaviors.  

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