Young scared couple watching a horror movie

(© Drobot Dean -

PASADENA, Calif. — Fear really is contagious, and scientists say having more people around you for support won’t help. So much for “strength in numbers.”

Researchers from the California Institute of Technology used a haunted house experience with 17 rooms containing various spooky threats during their experiment. They found people were actually more scared when the group walking through the house was larger. The team also found that their fear built up and increased as people moved from room to room.

Scientists say when faced with fear, people are more likely to have a heightened physical response when other people are around. This “phasic effect” involves rapid changes the body experiences as it responds to an event and is more likely to happen when other people are dealing with the same thing.

So, if a friend is shaking with fear and reacts to traumatic triggers, the study finds even the calmest person may also be startled by that trigger.

The study invited participants to go through the haunted house either alone or in a group and asked them to wear physiological-monitoring wristbands. During the 30-minute experience, they encountered situations that mimicked the threat of suffocation, an oncoming speeding car, and a volley of shots from a firing squad.

Results showed a positive association between the number of friends in a group and tonic arousal — which reflects the body’s overall physical response to stress or emotion. On average, the more friends that participants had with them while touring the haunted house, the higher their physical response. Other findings revealed that participants with an initially strong response to the first room of the haunted house showed increased responses as they visited other rooms.

‘Your body picks up’ on a scared friend’s signals

“There are a lot of factors that influence how human bodies respond to threat,” says Dr. Sarah Tashjian in a media release. “We found that friend-related emotional contagion, threat predictability, and subjective feelings of fear were all relevant for the body mounting a response.”

“We interpreted this to reflect fear contagion—if your friends are around, your body picks up on their signals and has a higher level of arousal even in the absence of specific scares or startles,” Tashjian adds. “In the lab, it is difficult to study the effects of groups on physiology.”

“If your body is more cued-in to the threatening event, you also psychologically feel more fear,” the study author continues.

“From a results perspective, this study is distinct because we measure multiple aspects of skin conductance, including slow responding, rapid responding, frequency of responses, and level of responses,” Tashjian explains. “Most studies use just one of these measures, which limits our understanding of how dynamic the sympathetic nervous system is and how different factors exert different influences on biology.”

“We show that friends increase overall arousal, that unexpected scares produce more responses and higher levels of responses in the body than predictable scares, and that more frequent responses from the body manifest as feeling more afraid,” the researcher concludes. “And we show all of this using an intensive, immersive, live-action threat environment.”

The research is published in the journal Psychological Science.

South West News Service writer Joe Morgan contributed to this report.

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