CHICAGO >> It seems to defy the logic of committing crimes in a way to avoid getting caught: Ruffians intentionally recording themselves on video beating and robbing someone, then posting it on YouTube so anyone anywhere can see it, including police.

The latest example of this disturbing but increasingly common phenomenon comes from Chicago, where police Wednesday arrested seven teens who apparently did just that. Their video had gone viral and led to their arrest within just days of the Sunday afternoon attack.

The practice, some experts say, is a modern twist on the age-old human penchant for boasting about one’s exploits to impress the community at large and to warn perceived rivals that their group is more powerful than others.

"Medieval warriors putting the heads of their enemies on sticks, scalping and even school yard brawls in the ’50s — they’re all ways of displaying that dominance in public," said Pam Rutledge, a Palo Alto, Calif.-based psychologist who heads the Media Psychology Research Center. "These new tools — the Internet, YouTube — just let you spread the word much farther."

Throughout the more than three-minute video, the attackers — many with sweat shirt hoods over their heads and some wearing masks — are seen yelling at the visibly terrified victim, punching and kicking him in the face with apparent glee as he curled up on the snow-covered ground. Police believe the lone girl involved lured the victim to the alley on the city’s South Side.

The urge to post incriminating material online, whatever the underlying motivation, might say as much about someone’s shaky grasp of how cyberspace works.

"These guys are bragging online without understanding they just provided irrefutable evidence of a crime," she said. "It says something both about their naiveté — and their stupidity."

Speaking to reporters after the arrests in Chicago, Police Superintendent Gary McCarthy noted that episodes of youth violence ending up in online videos have become more frequent everywhere.

"This is a national epidemic," he said. "It’s not something that’s particular to Chicago."

He also expressed bewilderment about why the teens decided to post the video, thereby incriminating themselves.

"I think it’s all part of the same dynamic where this is what kids do today, which is ridiculously stupid," he said.

The Chicago teens were charged in the beating and robbery of a 17-year-old high school student in an incident that stemmed from a previous dispute last October, police said. Police said the posted video helped to identify the alleged attackers.

One teen was charged as an adult. The rest — a 15-year-old girl, two 16-year-old boys and three 15-year-old boys — were cited in juvenile delinquency petitions. All face one count each of robbery and aggravated battery, including the teen who recorded the video.

A striking aspect of the Chicago video is just how at ease the attackers seem to be with being filmed. One attacker even pauses from kicking and punching the victim’s face to calmly instruct whoever is holding the camera how to compose the shot. He then walks back and resumes pummeling the boy.

Viewers who posted comments online identified the alleged attackers by name, including 17-year-old Raymond Palomino, who appeared in bond court Wednesday, his head bowed and looking ill-at ease. His bail was set at $100,000. Palomino’s face is visible in the video.

Police said the attackers stole shoes, a wallet and $180 in cash from the victim, who was treated at a hospital for a laceration to his lip, bruises and abrasions.

Another website provided an outlet to fan the flames leading up to the attack.

Raymond Palomino’s father claimed Sunday’s beating followed an after-school attack on Raymond and another boy. Michael Palomino, a Cook County sheriff’s deputy, said incendiary comments posted on Facebook after the alleged beating of his son contributed to the situation spiraling out of control.

"They’re making it sound like he did everything," Palomino said, speaking to reporters following his son’s initial appearance in court Wednesday. "It’s just one side of the story."

The sheriff’s deputy, who said he turned his son in after seeing the viral video, conceded what his son did was wrong. But he also accused prosecutors of exaggerating his son’s role.

The video-recorded attack on a teen in Chicago isn’t the first to attract attention on the Web. In 2009, footage of the fatal beating of a 16-year-old honor student was circulated worldwide.

In that video, captured by a cellphone camera, Derrion Albert is seen being punched, hit on the head with large boards and kicked in the head. The fight broke out after classes were dismissed at a high school on Chicago’s South Side.

Four teens were sentenced to lengthy prison terms last year in that case, which sparked outrage around the country. A fifth suspect tried as a juvenile was ordered to remain imprisoned until he turns 21.

The most recent incident was different in that the attack was videotaped by someone apparently affiliated with the attackers. The Albert attack was recorded by a bystander.

That these latest attackers beat the victim and uploaded the video to YouTube not only illustrated their immaturity, it also suggests they are deeply insecure, somehow calculating that the stunt would boost their social standing, Rutledge said.

If that was their thinking, they badly miscalculated.

"They are getting the opposite reinforcement that they intended," Rutledge said, citing the arrests. "They put it up to show how cool and tough they were. Instead, it left people thinking, ‘You guys are complete idiots.’"