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A few years ago, neurobiologist sat down with child- and youth psychiatrist to brainstorm about social behaviour. How can you measure social behaviour objectively? They came up with the idea of using mobile telephones with the ultimate goal of understanding how deviant behaviour occurs.

“Scientists often use questionnaires about behaviour, which the patients fill in themselves”, Kas explains. “That is a very subjective standard. I have a lot of experience working with animal experiments in which we accurately chart out the animal’s behaviour using tracking systems. That’s when Jacob and I thought: can we use the same techniques to objectively measure human social behaviour as well?

They realised that mobile telephones would be an excellent medium. “Everyone has one, after all.” That was the kick-off for BeHapp, an app that collects purely quantitative data. Kas emphasises that the owner of the mobile phone does not have to do anything. “You install the app, and then we’d prefer that you forgot about it.” Naturally, the researchers inform the users which data they will be registering in advance, and the participants have to give permission for them to save the data.

Measure today, know tomorrow

BeHapp silently measures incoming and outgoing communications: not the content of the messages, but how long or how often the participants use apps such as WhatsApp. It also monitors where you are. “GPS tracking is fairly simple, but we add a social context. We can see if you are in a densely-populated area, and Bluetooth signals and information about WiFi access points provide an indication of the social areas you move through.”

The project is ready for use within the research theme Dynamics of Youth, for example in the , which follows the development of thousands of children. “YOUth began with children aged 8, 9 and 10. The plan is to include the app in the study when the children return after they turn 12, 13 or 14.”

BeHapp is also used with other cohorts, such as the and the : “The BRIDGE study deals with children of schizophrenic and bipolar parents. These young adolescents run a higher risk of falling ill as well. The question is: can we identify differences between these young people and a control group, such as the YOUth cohort, at an early phase of their development?” The researchers hope that the knowledge gained will help to predict problems. “We may eventually be able to say: this young person is at risk of developing a behavioural disorder.”

"Let’s build a device for objective measurements."

Deceptively simple

BeHapp is now a good product, but it took a lot of work to get there. “In the beginning, Jacob and I were very naïve: let’s build a device for objective measurements. We completely overlooked the fact that it would gather a lot of privacy-sensitive information, which has to be stored securely. And smartphone technology innovates very rapidly, so how can you ensure that your app will be able to keep up?”

Martien Kas currently works in Groningen, but the collaboration with Jacob Vorstman in Utrecht is still strong. The team also includes , who works on the continuing development of the app together with an IT firm.  develops algorithms that enable the researchers to retrieve useful information from the raw data.

The technical and scientific expertise within the team is sorely needed. They had to invest a great deal of time and resources into the privacy issue, because it was one of the first things that the potential participants asked about. “It seems simple, but how can you collect the information without unveiling the individual behind it?”

For example, the researchers want to know how many different telephone numbers the participant calls. “We ensure that each number is given its own, unique encryption. So we cannot see the telephone number, only if you are calling the same person or not. GPS data is also identifiable, so Niels has developed algorithms that he can use to retrieve patterns of motion from the data, without it being linked to a geolocation.”

The foundations of behaviour

After the raw data is retrieved, the exciting part begins: how can you link it to deviant behaviour? Kas has a concrete goal in mind. “I am a biologist, so I want to understand the foundations of behaviour. In my animal experiments, I try to understand how the biology behind social interaction works in animals.” Child- and youth psychiatrist Jacob Vorstman also aims to apply the knowledge gained to his own field: what can the objective behaviour measurements in BeHapp tells us about how psychiatric disorders develop?

What can BeHapp tell us about how deviant behaviour occurs?

The team is currently developing algorithms that can be applied to human GPS tracking data as well as animal video tracking data. “That way, we can build a bridge between the two and learn more about the biology of human behaviour. That may help us understand it better when something goes wrong. What roles do genes, neural connections or environment play? If we know how deviant behaviour occurs, then we will be able to intervene more effectively. But that’s still a distant horizon, and I understand that we have a long way to go.”

Dynamics of Youth

BeHapp is ready for use within Dynamics of Youth,  one of ľ�ϸ���Ӱ��'s four strategic themes. Dynamics of Youth combines excellent child research from all seven faculties. Within Dynamics of Youth, researchers from different disciplines integrate their expertise to answer crucial questions for future generations. How can we help our children develop into balanced individuals, that are able to function successfully in a rapidly changing environment?