Dr Coleman's involvement with teenagers began in 1958 when, aged 18, he spent a year between school and university working with post-revolution Hungarian refugees in Austria.
As the youngest volunteer, he helped displaced people of 16 and 17. 'By the time I was in Austria, many of the refugees had left to start new lives in Australia and Canada, but those who had been left behind were the difficult, disruptive ones who no one wanted,' he explains. What was exciting was discovering a subject which was to influence his whole career.
He always intended to read psychology at university, and says he was lucky enough to get a place at McGill, in Montreal, Canada. 'It had an exceptionally good psychology department,' he says. He again worked with disturbed teenagers during his vacation. One hot summer was spent in New York, working as a volunteer in a church project to keep poor black teenagers off the streets.
'We tried to keep them away from the gangs that formed during the summer. We organised trips to Coney Island and held discos where there were as many police as partygoers. It was incredible - a very powerful experience,' says Dr Coleman, continuing quite calmly that there were two murders during his time there.
After training as a clinical psychologist in Britain and pursuing an academic career until 1970, Dr Coleman decided on a career change. He wanted to do more work with teenagers and at that time, he says, few psychology departments were studying children, let alone adolescents. It was time to do something 'more interesting and challenging'.
He plunged into founding Chalvington, a therapeutic community for disturbed children, aged between 11 and 16. The intention was to run the community while doing research and training. In practice, this was far too ambitious: the children - who were in care, having burned through several foster homes - were too needy and too damaged to allow for anything else. 'All our energy and concentration was spent on running Chalvington. It was unbelievably stressful and a bit of a shock,' he admits.
Eight years later, Dr Coleman founded the trust to undertake research into adolescence. One of its first projects - investigating the needs of children in residential care - drew on the experiences at Chalvington. At the same time, the trust developed a series of audio tapes and booklets designed to help parents of teenagers.
'We feel they don't get much support. People find it very difficult to acknowledge that the parenting of teenagers is a skill; there is an assumption that people can do it, or have to do it,' explains Dr Coleman.
The series - which includes topics such as divorce and step- families, sexuality, young people under stress, teenagers and alcoholism - is still expanding. An information pack on suicide and self-harm is currently in production. Dr Coleman would like to reach more parents - about 70 per cent of the packs are sold to professionals working in the field, for whom the trust also organises training courses, but financial constraints prevent advertising.
A crucial aspect of the trust's work is giving young people a voice. 'We need to be in touch with kids which is why they speak on the audio tapes. We have to ensure that we are listening, and not just sitting in our offices writing papers,' says Dr Coleman.
The trust acknowledges that the circumstances in which adolescents are growing up are more complex these days. Contributing factors are changing family structures and types, less resources for young people, and a lack of opportunities for employment. 'It means kids are leaving home later - they are worried about jobs, housing and money,' explains Dr Coleman.
Collaborating with the University of Wales, the trust is at present undertaking a focused study into the effects of divorce on young people: they are watching the family during the year of the divorce, and then for a year afterwards. 'We'll probably see that it is not just the divorce itself, but what has been happening before that plays a large part in how kids adjust. If there has been a long history of chronic conflict or abuse then often the divorce is a relief,' says Dr Coleman.
Some teenagers even find divorce quite positive if they are given more responsibility within a one-parent family, especially if previously they felt held back and prevented from growing up. Within the same study, the trust hopes to glean more information about the often forgotten non-residential parents, especially fathers, who frequently feel excluded and rejected.
Another study, which is about to begin, will challenge the image of young people. 'It is a philosophy of the trust that we don't just look at difficult behaviour. There is a widespread stereotype that adolescence is a difficult stage. Research shows that even though there are conflicts and challenges, relationships between parents and teenagers are not as bad as people assume.'
The project will look at different types of behaviour, including altruism - what teenagers do to help others for no tangible gain - and campaigning; how young people become involved with projects or organisations which matter to them.
'We want to see who does it, what effect it has - does it turn them off, do they never want to be involved again? And also, what impact does it have on their family life and their schoolwork,' says Dr Coleman. It will also discover whether schools encourage children to do community work.
In spite of the difficulty in finding money for the research projects, Dr Coleman is undoubtedly pleased with the trust's progress. And he can also demonstrate that the work is not solely based on other people's children.
Dr Coleman has two sons in their twenties, and two daughters aged 11 and 13. 'It is such a different experience having girls and boys. Privacy and personal space is very important for girls, and they are challenging at a younger age.
'I learned a lot from the boys, especially about identity. Occasionally they said, 'Don't start being a psychologist with me, Dad.' It keeps your feet on the ground,' he says.Reuse content