Does it have to be on video to get us to act?

A cellphone video captures the image of a man as he illegally entered the White House front door this month. As a result, the public is now engaged in a spirited debate about how best to improve security at 1600 Pennsylvania Ave.

Too bad there was no video of the White House shooting in 2011. A gunman out to kill President Barack Obama strafed the second and third floors of the White House, on the south side where the president and his family live. There were news accounts, but not as many as you might expect, and pitifully few follow-ups on the arrest of the shooter.

And there was virtually no public discussion about preventing that kind of security breach.

Such is the power of the video. In a society where people are reading less and watching more videos, the influence of the visual over our behavior will only grow.

The search for 18-year-old Hannah Graham, a University of Virginia student who disappeared Sept. 13, intensified as media continued to show three surveillance videos that were released by police in Charlottesville. Hopefully the attention will lead to her whereabouts and a safe return to her family.

You’d like to think that anyone who went missing would warrant the same dedication and concern. We shouldn’t have to see Hannah’s face on a security video to feel the nightmare that her parents were going through. Just knowing that she is missing should be enough.

However, during the past five years, four other women have gone missing in that college town. In those cases, there were only photographs of the victims. Media coverage quickly waned, as did public interest in making the streets of Charlottesville safer.

Maybe interest will be rekindled now that one of the missing women has been “humanized” by video.

In Ferguson, Mo. , where an unarmed 18-year-old, Michael Brown, was fatally shot by police last month, black youths have begun wearing body cameras to record their encounters with police.

If they are mistreated, the cameras would help them prove their case.

David Whitt, a spokesman for the California-based company that distributed the cameras, told the Associated Press that the devices would give black residents the ability to “challenge the police narrative.”

Nevermind that statistics compiled by the Missouri attorney general’s office show a decade-long pattern of police misconduct in Ferguson. Blacks have been beaten, racially profiled while driving and pulled over at rates much higher than white drivers. And yet, whites are caught with far more contraband than blacks.

But the numbers and testimony of residents have not been enough. It has to be on video to be real. Sadly, what gets our attention and moves us to act is the graphic and grotesque. Just look at what has happened since fanatics in the Middle East began posting beheadings on YouTube. Suddenly a war-weary nation ramps up for the “war on terror” anew.

The ugliness of domestic violence is only recognized after an elevator camera catches a football player punching his fiancee.

And what about all of those fathers and mothers going on rampages in recent months and killing everyone in their families? There was another Friday: A 51-year-old Florida man killed his daughter and six grandchildren before killing himself. Where is the outcry over these atrocities?

At least 450 children a year are murdered by their parents, according to a recent USA Today analysis of FBI statistics, with three out of four of them under 5 years old.

But there is no video of those mostly normal-looking dads as they go around the house blowing the kids’ brains out. So we dismiss their actions as “unfathomable,” while accepting easier-to-grasp images from an elevator camera or a video of a man running across the White House lawn.

The security video made the NFL the face of domestic violence and Ray Rice the focal point of debate among fans and foes over whether his behavior was to be condemned or excused.

Seeing is believing. Out of sight means out of mind. Surely there are better ways to comprehend reality.

Blind people don’t need sight to do right. Why do we?

Courtland Milloy is a columnist for the Washington Post.