[MUSIC] I think one of the main challenges for people is that you have to live together and cooperate, and otherwise, we're gone. And so I'm really interested in how people manage to live together, work together, and get along. And I found that the foundations for that are lead in childhood, and that it's really fascinating to see why it goes wrong. But also, why it doesn't go wrong with most people, and people manage to replace their aggressive tendencies by more prosocial skills and more prosocial behaviors. So we've seen that these children made these hostile attributions, and that leaves them to become aggressive. So when we make these games, and we interact with each other, we could easily evoke aggressive behavior between them because they made hostile attributions. Because they thought that the others hindered them on purpose, and they wanted to take revenge. We study how aggressive behaviors like bullying develop and what we can do to prevent them from developing or to cure them. And we do so in different ways, because aggressive behavior problems can develop for very different reasons in different children. So we first tried to detect why the problems emerged. Are there family problems, or are there problems in a child's temperament? Or is it more something in the school context in the classroom? And then, after we found out what may be the cause of these behavior problems, we look for ways to present those problem or treat those problems. And we test whether those solutions actually work. So how shall we go about it? I think the scientific challenge for me personally is to see whether all these things that are associated with problems in children, which of these things are actually the causes of the problems, and which are just the consequences? And we use these interventions to test whether if we change something, it really also diminishes the problems the children have so that we know that it's actually a causal process. So scientifically, doing these interventions with kids is a nice way to test causality. That may sound a bit abstract, but it's really helpful. Because at the same time, you can use these interventions to really improve children's lives in the long run. These facts of bullying research that maybe we could evaluate the most promising programs. It used to be that there was this divide between people who study normal development and people who studied children with really severe problems. And it was really stupid because we can learn a lot from each other. If you want to understand why some children get into problems, like many of the children I've studied, you have to understand why most children don't develop these problems. So you have this continuum between normal development and problematic development, and you really need to work together to understand what makes development go right and what makes development go wrong. And in dynamics of youth, we put that together, so that's really nice. And also, you need to understand not just the child, and his genes, and hormones, and his family, but also the broader environment. Like for example, the culture a child come from, or grows up in, or socioeconomic problems the children may have that may put really the stress on families that make it more logical for parents to raise their children adequately, or for children to develop behavior problems. [MUSIC] Now, I guess one tip is just patience. Because sometimes people come with ideas that are really far removed from the way that you tend to think about things. And you have to just take the time to let it sink in. A good example is game theory where you have these theorists who just spend all their time simulating games where people can win or lose in different contexts on computers. And I felt first that it was very far removed from what I did. But then later on, I saw that, hey, bullying in the classroom. You can approach that very well with game theory by looking at what have the different children in the classroom to gain from intervening with bullying or helping the bully or helping the victim? And that suddenly, it turned out an approach that was really helpful understanding bullying. Even though at first, it seemed far removed from what I was doing. So you need some patience and some sort of an empty mind to start with an open eye. Look at something that first you might think, hey, what does this have to do with what I'm doing? But those are the very things that then may tempt you to find a new direction where you may actually discover new things. [MUSIC]