WASHINGTON (AFP) ― 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 U.S. study suggested.

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 U.S. soil since Sept. 11, 2001.

The findings were based on a survey of 4,675 adults taken shortly after the deadly April 15 attacks and the frenzied five-day manhunt in which one suspect, Tamerlan Tsarnaev, was killed and his brother, Dzhokhar, was arrested.

Dzhokhar Tsarnaev is accused of setting off 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.