Teenager Admits Lying About Colorado Shooting

Sixteen-old-Cassidy Grigg apologized on national television for lying about his role and whereabouts during the taking of hostages at Platte Canyon High School, in Bailey, Colo, on Wednesday. Grigg claimed he was in the classroom when Duane Morrison took six girls hostage. He originally said he wanted to stay with the girls to try to protect them. Turns out, it didn't happen that way.

"I made a really big mistake," Grigg told "Good Morning America." " I told the U.S. and the world something that's not true. I came here to make it right."

"Everyone wants to be a hero," said psychologist Robert Feldman. As associate dean of the University of Massachusetts' College of Social and Behavioral Sciences, Feldman has studied lying.

"Everyone wants their 15 minutes of fame," he said. "People very often try to embellish what they actually accomplished to achieve that fame at the expense of truth."

Regarding Grigg and the role he claimed to play in the Colorado high school hostage crisis, his mother said her son "got caught up in the chaos" amid all the television crews.

"There's a slippery slope with lying," Feldman explained. It's likely Grigg "didn't realize what would come of this until it was possibly too late, and there was no easy way out."

Feldman said people might lie to gain notoriety. Often "people feel they should have done more than they did. ... One way of compensating is to lie about what actually happened.

"We learn at a very young age to present ourselves well and are concerned about what others believe," Feldman continued, adding that to accomplish that "we often deceive."

And, psychologists say, the more people lie, the better they get at it.

Take James Edmiston, a California man who claimed he was a computer expert and went to jail on charges of duping defense attorneys. Edmiston gave expert testimony on computer cases in numerous California courtrooms, from Sacramento to Los Angeles. Investigators said he had falsified his resume and lied about his experience. Edmiston told the special agent who arrested him that he had been "lying so long that he actually began believing the lies himself."

Feldman said people often believe they have no choice but to stick to their original story.

Cassidy Grigg decided to come clean. But Feldman said his original lie "will say with him for a very long time. Not only was he caught lying in a very public way, he has to live with friends who lost someone and with people who actually did act heroically." Feldman said Grigg's lie could "diminish his status and his credibility" for some time to come.