By Kathryn Westcott
The Austrian children locked in a cellar with their mother since birth have been through an experience that is hard to imagine.
There was one room to sleep in and one to cook in
But experts say the psychological damage they have suffered could be less severe than you may think.
The two boys - aged 18 and five - and their 42-year-old mother Elisabeth Fritzl are said to be receiving medical and psychological treatment. The 19-year-old girl, Kerstin, is in a coma in hospital for reasons that are unclear.
Ernst Berger, the psychologist who worked with Natascha Kampusch - who was abducted at the age of 10 and held in a cellar in Austria for eight years until 2006 - said Elisabeth and her children could be suffering from a variety of traumas.
He said they would need extensive psychological counselling if they were ever to have a chance of regaining normal lives.
A 'real car'
"The consequences of the psychological trauma can be very varied, from severe depression to feelings of suicide, or social phobia, such as wanting to shut themselves of from people, but they differ from individual to individual," he was quoted by Reuters as saying.
"They have panic attacks, fears and nightmares. It depends on their way of life as to how it manifests itself."
Details about the case are still emerging, but, local official Hans-Heinz Lenze said he had spoken to the five-year-old boy.
The rooms in the cellar were described as very narrow
"I attended a clinic in Mauer, and I talked with social workers there, I visited members of the family and during this visit I could see that the five-year old boy is in a better condition," he said.
"He even told me how happy he was and how fantastic it was to ride in a real car."
According to police, the mother taught the children to speak. It is also believed they had a television, although it is not known for how long.
Professor Jay Belsky, an expert in the field of child development and family studies at Birkbeck College, University of London, says the fact that the children were with their mother - a source of security - and with each other, could have mitigated the amount of trauma they suffered.
"Potentially, the children could have led tolerably rich social lives - there were four people there, at least three of them for a long period of time. This isn't a story about a child being locked in a closet all by himself," he told the BBC News website.
He said that in terms of the five-year-old, he would have been unlikely to have known what he was missing.
"As a youngster, your immediate environment is your whole world," he says.
"If there were books, games and a TV, there were things for all the children to make a psychological life around. It need not be as atrocious as it might first appear," he says.
Three of the children lived upstairs with the grandparents
However, Professor Belsky stressed that much of this would be dependent on the mother's mental state.
"It's hard to imagine that her own mental well-being was not compromised, and this would have undermined her ability to support and nurture her children," he says.
Police have said Elisabeth appeared "greatly disturbed" during questioning.
Professor Belsky suggested that the TV could have taught the children some notion of appropriate social behaviour and about the wider world.
However, he said, there would have been problems with the older children when they realised that this was not just an imaginary world, but a real one that they were being deprived of.
"This would have only added insult to injury," he says.
Professor Belsky said there was no doubt the children would bear some psychological scars.
"It's hard to imagine that the teenagers would ever lead truly normal lives like you and I would think of, but even development at that late age is possible - social skills are learnable," he says.
He says the repetitiveness of their existence would not have offered them much of a cognitive challenge, or much opportunity to encounter novelty.
"They might end up being stunted in their natural curiosity about how the world works," he said.
But he sounded a note of optimism: "We've seen enough surprises in human development of children doing better than expected under seemingly atrocious conditions," he says.
Peter Fonagy, director of the research department of clinical, educational and health psychology at University College London, said the children were likely to suffer significant social problems in the medium term because of their lack of social interaction.
"They are likely to suffer significant cognitive and perceptual deficit and major problems with emotional regulation," he says. "The parts of the brain that read emotion in other people would not be so well developed."
But he said that cognitively, the five year old had a very good chance of catching up, and that, despite their ages, there was much the others could still learn.
"The human brain is marvellous in its ability to adapt to different circumstances," he said.
According to reports, the children are undergoing tests in hospital, in particular for problems with their eyes and skin due to the lack of daylight.
The children were reported to be very pale but in a good physical state.