There is a tendency to highlight the importance of cognitive achievements and the family's socioeconomic background for people's success in the future, but this study shows that children's self-regulation, which comprises children's social skills and processing of emotions, directs the future development in a profound way in different domains of life. Strong self-regulation promotes success in education and work, the intimate relationship, health behaviour, integration into society and the development of flexible personality, explains Professor Lea Pulkkinen.

The results of Jyväskylä Longitudinal Study of Personality and Social Development, which has taken place for more than 40 years, have been summarised in the book Human development from middle childhood to middle adulthood: Growing up to be middle-aged (London:Routledge) to be launched on 15 June 2017. The study started in 1968 when the participants were 8 years old and the latest data collection was implemented in 2009 when they were 50. The book is written by the founder and long-time leader of the study, Professor Lea Pulkkinen in collaboration with Research Director Katja Kokko from the Gerontology Research Center of the University of Jyväskylä. Kokko has been the leader of the study since 2013.

The extensive research summarised in the book demonstrates that constructive ways of coping with problem situations, the consideration of other people's feelings and a positive way of thinking as a child predict good functioning capacity in adulthood. The development of self-regulation is enhanced by child-oriented mature parenting.

Child-oriented parents are able to analyse their behaviour from the perspective of the child and create an environment in which children are able to sense warmth and approval from their parents as well as notice continuing dedication and interest towards their lives. Child-oriented parents also pay attention to the child's opinions and react to the child's needs in order to provide satisfaction and give support, Pulkkinen explains.

The study provides a plenty of new information on adulthood development which has been studied sparsely. Important matters in life are not limited to childhood. The transition to adulthood and the different roles of adults in the family and work create new situations in which humans can develop and mature to take responsibility for themselves and others. Harmful effects on adult development are, above all, caused by the excessive use of alcohol which usually is connected to starting alcohol use at an early age.

The study shows that people in midlife are usually healthy, capable to work and willing to take responsibility. They are active in different domains of life and their physical and mental well-being is good.

The research was conducted at the Department of Psychology at the University of Jyväskylä and has been supported financially for decades by the Academy of Finland.