Flu season is nearly upon us, and in an effort to limit contagion and spare ourselves misery, many of us will get vaccinated. The work of Jonas Salk and Thomas Francis has helped restrict the spread of the nasty bug for generations, and the influenza vaccine is credited with saving tens of thousands of lives. But before the vaccine could be developed, scientists first had to identify the cause of influenza — and, importantly, recognize that it was contagious.

New research by Trevor Foulk, Andrew Woolum, and Amir Erez at the University of Florida takes that same first step in identifying a different kind of contagious menace: rudeness. In a series of studies, Foulk and colleagues demonstrate that being the target of rude behavior, or even simply witnessing rude behavior, induces rudeness. People exposed to rude behavior tend to have concepts associated with rudeness activated in their minds, and consequently may interpret ambiguous but benign behaviors as rude. More significantly, they themselves are more likely to behave rudely toward others, and to evoke hostility, negative affect, and even revenge from others.

The finding that negative behavior can beget negative behavior is not exactly new, as researchers demonstrated decades ago that individuals learn vicariously and will repeat destructive actions. In the now infamous Bobo doll experiment, for example, children who watched an adult strike a Bobo doll with a mallet or yell at it were themselves abusive toward the doll. Similarly, supervisors who believe they are mistreated by managers tend to pass on this mistreatment to their employees.

Previous work on the negative contagion effect, however, has focused primarily on high-intensity behaviors like hitting or abusive supervision that are (thankfully) relatively infrequent in everyday life. In addition, in most previous studies the destructive behavior was modeled by someone with a higher status than the observer. These extreme negative behaviors may thus get repeated because (a) they are quite salient and (b) the observer is consciously and intentionally trying to emulate the behavior of someone with an elevated social status.

Foulk and colleagues wondered about low-intensity negative behaviors, the kind you are likely to encounter in your everyday interactions with coworkers, clients, customers, and peers. We spend far more of our time with coworkers and clients than we do with supervisors, and so their actions, if contagious, are likely to have a much broader effect on us. Evidence for negative contagion among peers and customers might also suggest that there is more than one mode of infection. We are far less likely to intentionally base our behavior on our customers than we are on our bosses, and thus any behavioral contagion observed in these settings is likely driven by unconscious, unintentional processes rather than by purposeful imitation. Perhaps we can “catch” behaviors without even trying.

Foulk’s team first explored whether low-intensity behaviors like rudeness are contagious. In one study, they examined whether observing rude behavior activates concepts related to rudeness. Participants first completed a brief 15 minute survey, and when they were finished, a confederate playing the part of a late participant arrived at the study and asked to be included in the study. In the control condition, the experimenter politely told the late participant that the experiment had already begun and offered to schedule her for another session. In the negative condition, the experimenter rudely berated the late participant and told her to leave. All participants then completed a lexical decision task (LDT) in which they decided as quickly as possible whether strings of letters (e.g., CHIKHEN) formed a word. Critically, some of the LDT words were friendly (e.g., helpful), some were aggressive (e.g., savage), and some were rude (e.g., tactless). Response times to the friendly and aggressive items were similar across conditions, but response times to the rude items were significantly faster for participants in the negative condition relative to the control condition. People who watched a rude interaction had concepts about rudeness active in their mind, and thus were faster to respond to those concepts in the LDT. These findings suggest that exposure to rudeness seems to sensitize us to rude concepts in a way that is not intentional or purposeful, but instead happens automatically.

To examine whether this sensitivity impacts social behavior, Foulk’s team conducted another study in which participants were asked to play the part of an employee at a local bookstore. Participants first observed a video showing either a polite or a rude interaction among coworkers. They were then asked to respond to an email from a customer. The email was either neutral (e.g., “I am writing to check on an order I placed a few weeks ago.”), highly aggressive (e.g., “I guess you or one of your incompetent staff must have lost my order.”), or moderately rude (I’m really surprised by this as EVERYBODY said you guys give really good customer service???).

Foulk and colleagues again found that prior exposure to rude behavior creates a specific sensitivity to rudeness. Notably, the type of video participants observed did not affect their responses to the neutral or aggressive emails; instead, the nature of those emails drove the response. That is, all participants were more likely to send a hostile response to the aggressive email than to neutral email, regardless of whether they had previously observed a polite or rude employee interaction. However, the type of video participants observed early in the study did affect their interpretation of and response to the rude email. Those who had seen the polite video adopted a benign interpretation of the moderately rude email and delivered a neutral response, while those who had seen the rude video adopted a malevolent interpretation and delivered a hostile response. Thus, observing rude behaviors, even those committed by coworkers or peers, resulted in greater sensitivity and heightened response to rudeness.

Exposure to rude behavior clearly affects our mindset and the way we respond to rudeness, but Foulk’s final study revealed an even more unpleasant side effect of the contagion: watching rude behaviors leads us to be rude to others, and those others may then be rude (or worse) to us.

Participants in the study engaged in a series of negotiation exercises with other participants. The key question centered on the behavior of participants who encountered a rude partner. How did they behave in a subsequent negotiation? How did their next negotiation partners feel about them and treat them?

As you might guess, participants who negotiated with a rude partner were in turn perceived as rude in their subsequent interaction with a new partner. These “carriers” evoked feelings of anger and hostility in their new partners, and even incited vindictive behaviors. After the negotiation between the carrier and the new partner was complete, the new partner was privately given the opportunity to decide how to distribute additional resources with the carrier. The new partner could make a prosocial choice and split the resources evenly, could make an individualistic choice and take more of the resources for herself (leaving some for the carrier), or could make a hostile choice by destroying all resources, thus ensuring that the carrier received nothing (but also losing out on any resources herself). The hostile option was selected significantly more often after interactions with a carrier, suggesting that people were willing to suffer personally in order to exact revenge on the carrier. Moreover, these effects of negative contagion were evident in negotiations that took place up to a week after the initial exposure, suggesting a fairly long infectious period for negative behaviors.

Collectively, the data from Foulk and colleagues highlight the dangers of low-intensity negative behaviors, even those that are merely witnessed rather than personally experienced. With negative behaviors, the witness becomes the perpetrator, just as the person who touches a doorknob recently handled by a flu sufferer can themselves get sick and infect others. No conscious intent in necessary, and the contagion may last for days. Unfortunately, unlike the flu, there currently is no known inoculation for this contagion. Where is Jonas Salk when you need him?