After the Boston marathon bombings, people who spent six hours a day scouring media for updates were more traumatized than those who were actually there, a US study suggested Monday.
The study raised questions about the psychological impact of repeated exposure to violence via digital and traditional media in the first major terror attack on US soil since September 11, 2001.
The findings were based on a survey of 4,675 US adults taken shortly after the deadly April 15 attacks and the frenzied five-day manhunt in which one suspect was killed and his brother was arrested.
The brothers set of homemade pressure cooker bombs at the race's finish line, killing three people and wounding 260, some of whom had limbs blown off by the force of the blasts.
Many of the bloodiest images were cropped or modified by major media outlets, but unedited pictures snapped by witnesses and raw video circulated widely on Twitter, YouTube, Facebook and other social media, said study co-author Roxane Cohen Silver.
"What was striking was the impact of this media exposure even for people who knew nobody, who weren't there that day," Silver, professor of psychology at the University of California Irvine, told AFP.
"Media exposure was a stronger predictor of acute stress response than having been there," she said.
Acute stress response was defined as a set of symptoms including intrusive thoughts and ruminations, flashbacks, feeling on edge or hypervigilant, and trying to avoid reminders of the event.
Survey respondents were asked within two to four weeks of the bombings about their media consumption the week after the attacks, and about their psychological stress symptoms.
People who were there, or who knew someone who was, were more likely to experience signs of acute stress than people who were not there, and were also more likely to view more media about the attacks, said the findings in the Proceedings of the National Academy of Sciences.
But an even stronger indication of psychological stress was whether a person viewed and read six hours or more per day of media pertaining to the bombings, said Silver.
"It wasn't that the direct exposure was not important, it was just that above and beyond having been there, media exposure was an even stronger predictor of acute stress response," she said.
When comparing people who viewed one hour a day of media about the attacks to people who consumed six hours or more, the latter group was nine times more likely to report acute stress, said the study.
Silver said the average media consumption by survey respondents was 4.7 hours per day, and typically included browsing social media, watching videos of the bombings, reading news stories and viewing television news reports.
Bruce Shapiro, executive director of the Dart Center for Journalism and Trauma at Columbia University, said the study's findings raise important ethical questions for news organizations, and are in line with previous research on a phenomenon known as "vicarious traumatization."
However, he pointed out that acute stress seen in the short term is not necessarily an indicator of post traumatic stress disorder (PTSD).
"It will take further study before we know if people's rise in acute stress symptoms turns into or feeds long-term psychological injury," Shapiro told AFP.
"It doesn't become PTSD until the characteristic problems go on for more than six weeks and interfere in some significant way with people's lives."
Silver said modern media has made it easier than ever for people to access images that may be disturbing, especially if seen over and over, and the new digital landscape can often leave it up to the individual whether to look or to look away.
"People should be aware there is no psychological benefit to repeated exposure to pictures of horror," she said.