Now that Jaycee Dugard has found freedom after 18 years of captivity, the world is wondering what will happen next -- and how her two children with accused kidnapper Phillip Garrido will adjust to a life outside the walls of their hidden backyard encampment.

Dr. Mark Goulston, author of the new book Just Listen, out September 15, tells ET that re-assimilating after long-term captivity is not without difficulty.

"When you are geared towards survival, your whole being doesn't know what to do with freedom," says Dr. Goulston. "So freedom could actually be temporarily traumatic to them."

"It's like having your psyche hit by a two-by-four," he says of Jaycee's transition from a normal, middle-class life to living in squalor within hours. "In order to survive, your psyche and your young personality at age 11 adjust to that -- I think it is traumatic and you do what you can to survive psychologically."

Dr. Goulston says he believes that despite the horror endured, healing is possible.

"It will be important at some point for Jaycee to share the details as much as she can," he says. "Having the horror heard helps heal the hurt."

Jaycee was allegedly abducted by Garrido in 1991 at the age of 11. Last week it was discovered that the girl, now 29 years old, was held in captivity for 18 years in Garrido's home in Antioch, CA. It was also revealed that they had two daughters together.

Watch ET for more details as this story unfolds…