Science explains: Why did Lance lie?

INDIANAPOLIS (WISH) - Your parents may have punished you for doing it.

Your employer could possibly fire you if get caught up in one.

And if you are Lance Armstrong, lying could tarnish your career.

Tonight the disgraced former Tour de France champion and American hero is expected to admit to using performance enhancing drugs.

But why did he lie initially?

Laura Mathews, a licensed psychologist says many think they lie to protect themselves. 

“Sometime they don’t believe they have the capacity to protect themselves and sometimes it is to protect other people,” Mathews said. “They also lie to avoid consequences.”

Mathews says people start lying as early as age 4 or 5.

While in office, President Bill Clinton denied the 1998 scandal. The allegations against him were true.

"I did not have sexual relations with the woman, Miss Lewinsky ," Clinton said at the time. "I never told anyone to lie.  Not a single time. Never."

Armstrong repeatedly questioned anyone who questioned him about his ability.

"There are no secrets — this is a hard sporting event and hard work wins it," Armstrong said following one of his Tour de France wins. "So Vive le Tour forever!"

Mathews says she can't explain what compelled Armstrong to conceal the truth. However, she said lies lead to destructive behavior.

"I get people in here to me they lie to everyone all the time and they don't know why," Mathews said, adding at times she is caught of guard but never surprised.