"Why didn't she try to escape sooner?" is the question on many people's minds in reaction to the Jaycee Dugard story.

Dugard was recently reunited with her family after being held captive for 18 years. She was apparently kidnapped at a bus stop near her home in South Lake Tahoe, Calif. when she was 11 years old. Since then she has lived in tents behind the house of her captors, Phillip and Nancy Garrido, along with two children born to Dugard and allegedly fathered by Garrido.

While this man's actions appear to many on the outside to be those of a monster, Dugard feels that her relationship with Garrido is "almost like a marriage," said her stepfather, according to the Associated Press.

Experts say it's actually not very surprising that Dugard developed a bond with her captor, and that she did not try to escape sooner. In numerous past cases, kidnapping and hostage victims have come to sympathize with their abductors.

"It is believed to be a common and expected occurrence," said clinical psychologist Paul G. Mattiuzzi, author of the blog EverydayPsychology.com. "The FBI has produced bulletins on this topic and has recognized this phenomenon and provided training on it."

Stockholm syndrome

The phenomenon is called Stockholm syndrome, after a 1972 bank robbery in Stockholm, Sweden, where bank employees held hostage for six days ultimately bonded with their captors. In that case the hostages resisted rescue, refused to testify against the robbers and even raised money for their legal defense.

Other famous cases include Patty Hearst, a rich heiress who was kidnapped in 1974 by the Symbionese Liberation Army, an American terrorist group. Hearst, who was 19 at the time, apparently came to sympathize with the group and even participated in a bank robbery with them.

One reason people may develop sympathy for their captors is a psychological idea called cognitive dissonance: When people recognize inconsistent views within themselves, they tend to alter their thinking to remove the conflict. A mundane example is the tendency of people to value a product more highly after they buy it. It's hard for people to think of a product as worthless, and think of themselves as smart consumers, at the same time, so they often come to think of their purchases as being worth more than they would if they hadn't bought the item.

Even in the more complex case of kidnapping, cognitive dissonance can come into play.

"Imagine you've been kidnapped and are in a situation of genuine threat and terror," Mattiuzzi explained in an e-mail. "In order to survive, you have to act compliant or act nice to your captor. There will be a tendency in your mind to achieve consistency: I'm acting nice to this person because they are nice."

Blaming the victim

While Stockholm syndrome sounds farfetched, it's based on well-known psychological effects.

"The only reason people question whether something like the Stockholm syndrome is real is because it seems so irrational," Mattiuzzi said. "But the thing is that our thoughts, feelings and behaviors are largely governed by unconscious and irrational processes."

Many people like to think they would be more objective in such a situation, and would have tried harder than Dugard to escape, but those kind of accusations are part of a persistent problem of blaming the victim, said New York trauma psychologist and author Elizabeth Carll. In truth, Stockholm syndrome appears to be relatively common among the few cases of long-term kidnapping that have been publicized.

"Whenever an abuser shows acts of kindness toward you, it shows you some hope that you will survive," Carll told LiveScience. "That combined with the terror of what could happen sets the stage for wanting to please the abductor, and eventually feeling positive toward the abuser as a way of coping."

The longer you are held captive, the more likely you are to bond with your captor, Carll said. In Dugard's case, 18 years with the Garridos is longer than she had lived with her own family.

"He has been the only source of support or any positive as well as negative interactions in her life because she's been so sheltered, so she doesn’t know anybody else to that degree," Carll said.

Survival strategy

Bonding with a kidnapper is not just a mental coping skill, but a physical survival strategy. Since Dugard's life was at the mercy of the Garridos, and she depended on them for food and shelter, it was in her best interest to bond to protect herself from further abuse.

"Someone who's kidnapped as a child might make an unconscious decision to not fully see the abuse and bond with the person providing food and shelter," said Jennifer Freyd, a psychologist at the University of Oregon. "A person might respond by putting it out of their mind and acting like it's not happening. It's too important to protect their relationship."

Freyd said Stockholm syndrome is similar to the reaction of many victims of domestic violence, such as children or spouses who suffer abuse at the hands of their parents or partners. She developed an understanding of their psychology called betrayal trauma theory. According to the model, victims who are dependent on their abusers often cannot acknowledge or fight against the abuse because their resistance might provoke retribution.

"Responding or fighting back may only cause the abuser to become even more abusive or stop taking care of them in a way that’s needed for survival," Freyd said. "If you're in a situation where you're really empowered to say no, you generally will. But if they're your only source of support, you're going to be really stuck if you alienate them."