When the video of four cops beating Rodney King nearly to death swept the country in 1991, it marked the first time many Americans had seen police brutality up close. It was also one of the first instances of sousveillance, a term coined in 1998 by Canadian academic Steve Mann that refers to private citizens monitoring or recording the activities of authority figures. The King footage was broadcast repeatedly on newsreels: It was everywhere you looked. After the officers involved were cleared of all charges, Los Angeles burned.

Today, sousveillance is more common than ever. Cellphone cameras are standard, and individuals and groups are empowered to film the police, though bystanders still face hostility from officers when attempting to record. Laquan McDonald, an unarmed black teenager killed last year by Chicago police, died in front of a police cruiser’s dashboard camera; the video, however, was suppressed by the department for a year, and has only just begun to circulate.

In America, graphic depictions of police violence toward black people show up in the media with unsettling regularity, because there seems to be a certain corrective impulse towards accountability through showing the unthinkable, publicly. On Democracy Now!, Ta-Nehisi Coates—this year’s National Book Award recipient for nonfiction—likened the moment to the fight for civil rights in the ’60s. “The violence that folks saw in Selma, for instance, or on Bloody Sunday, was not, in fact, actually new... What was new was the cameras,” he said. “There was certain technology that was able to take that into the living rooms of America. And we’re going through a similar thing right now.”

Seeing graphic violence goes further than thinking about racism’s effects on black people. What does it mean to watch relentless community trauma? We saw Eric Garner strangled to death on a sidewalk, and we saw a homeless grandmother, Marlene Pinnock, beaten within an inch of her life on the side of the highway. Laquan McDonald, standing in the street with his back to police, was shot sixteen times, and we saw his body prone and jerking unnaturally on the ground as bullets riddled his lifeless frame. What does that do to your mental health?

Because the phenomenon is so new, there’s almost no scientific literature on the psychological impact of seeing graphic violence in the media, the user-generated images produced from successful cop watching for instance. There are, however, studies that investigate the effect on the journalists who screen and edit graphic images before they make the news.