Media playback is unsupported on your device Media caption The BBC's Lucy Williamson says the news took people by surprise

The outpouring of grief in North Korea after the passing of Kim Jong-il has been fervent and widespread. So are the people sincerely feeling this loss or are they behaving as they think they should?

The North Korean nation took its cue from the state television presenter who was dressed in black and barely able to hold back the tears.

There followed tears, wailing and fists beaten against the pavement, but on a huge scale.

Men and women have been swept along on a wave of uncontrollable hysteria. "How could he leave us?" said one woman as she wiped away the tears.

The scenes were reminiscent of the mourning that followed the death of Kim Jong-il's father, Kim Il-sung, in 1994. So how genuine is the grief?

It's very difficult to know, says Anthony Daniels, a psychiatrist and writer whose pen name is Theodore Dalrymple. He visited North Korea in 1989 as a member of the British delegation to the International Festival of Youth and Students.

"It's a terrible mixture of fear, terror and apprehension about the future, mass hysteria and possibly genuine grief as well.

Competitive crying It's not easy to produce tears when you're not really feeling it but you could fake weeping and wailing and this mass hysteria makes it impossible to tell what is real. There's a kind of arms race situation in which you have to express yourself more and more extremely in order to demonstrate that you are feeling the orthodox emotions. A lot of it is perfectly compatible with acting. That isn't to say that it is acting, however. Anthony Daniels, psychiatrist

"It's very difficult to know the reality and I think we'll never know the reality. There are huge cultural barriers anyway and then you have to remember this is a regime where everything that isn't forbidden is compulsory, so it's difficult to know what their state of mind really is."

No expression of emotion was apparent during that 1989 visit he made, he says, except mass hysteria.

"When I was in the huge stadium and the Great Leader [Kim Il-sung] came in, everyone stood up and started worshipping him, quite literally worshipping him and letting out a roar at the same time.

"It might be that these people would be terrified not to do that but at the same time it's possible that many of them felt a genuine allegiance to the Great Leader.

"After all, when Stalin died, people wept in the streets, although it was less effusive than in North Korea."

In a very small way, there have been examples in the West when people have felt compelled to express emotions, says Mr Daniels, author of The Wilder Shores of Marx. After Princess Diana died, some people felt afraid to dissent from the mass grieving, but there is a huge difference with North Korea on the level of compulsion involved.

Mass grief 1953: It's estimated that millions of Russians went to Moscow to catch a final glimpse of the dictator Josef Stalin lying in state, with many openly weeping for the man they called '"Father", "Teacher", "God"

It's estimated that millions of Russians went to Moscow to catch a final glimpse of the dictator Josef Stalin lying in state, with many openly weeping for the man they called '"Father", "Teacher", "God" 1989: The death of the leader of Iran's Islamic revolution, Ayatollah Khomeini, was met with a frenzied outpouring of grief, with several crushed to death as his coffin arrived at the cemetery

The death of the leader of Iran's Islamic revolution, Ayatollah Khomeini, was met with a frenzied outpouring of grief, with several crushed to death as his coffin arrived at the cemetery 1997: Around a million people lined the streets of London as Princess Diana's funeral cortege made its way to Westminster Abbey, many in tears at shrines around the world (above)

Around a million people lined the streets of London as Princess Diana's funeral cortege made its way to Westminster Abbey, many in tears at shrines around the world (above) 2009: News of Michael Jackson's death on 25 June 2009 was met with tears, shrines and tributes from the singer's fans all over the world

In her book Nothing To Envy: Ordinary Lives in North Korea, Barbara Demick wrote, referring to Kim Il-sung's death in 1994: "The histrionics of grief took on a competitive quality. Who could weep the loudest?"

One young student in Pyongyang felt nothing as all around him were wailing, she noted. "His entire future depended on his ability to cry. Not just his career and his membership in the Workers' Party, his very survival was at stake. It was a matter of life and death."

He was saved, she wrote, by holding his eyelids open and his eyeballs exposed until they burned and began to tear up. Once they started, he began sobbing like everyone else.

For many it was probably a natural reaction, says Kerry Brown, head of the Asia programme at Chatham House, because learning about a leader's death raises questions for the North Koreans about their identity, their security and their ability to survive,

This is a nation that feels like it is always on a war footing, being looked after by their good and loving leader, he says. But we know no more about the real feelings of the Korean people than we know about the power struggles among the elite leadership.

"The control of information is so great that it's likely they feel real shock. So it's genuine hysteria but whether it's what we in the West call grief, we don't know."

They would be told they're under constant attack in a kind of constant war with the US, he says, and the "great victories" of the past were down to strong leadership, so the loss of the head in such a patriarchal system would be personally felt.

However, the grief in 1994 was much more shocking, he thinks, because Kim Il-sung's status in Korean society was much greater, so this period of mourning won't be as deep or as heartfelt this time.