Consortium on Individual Development

Dienke Bos and Roy Hessels on YOUth

Brein to byte

Text: Bruno van Wayenburg
Photos: Bram Belloni

Anyone entering YOUth does not immediately think: ‘This is a real data factory’. There are long tables where parents sit with their children, there is a toy crocodile lying around, and on the walls are photos of hundreds of children. It is more reminiscent of a day-care centre than a scientific institution producing gigabytes of research data.

But that is definitely the case, says Dienke Bos (1985) – executive director of the YOUth study, based in a cluster of outbuildings at the University Medical Centre Utrecht (UMCU). This large-scale cohort was set up a decade ago by the CID. It studies the psychological, social, and neurobiological development of Dutch youth, from pregnancy to adolescence.

Data factory
‘We have followed a total of 4,200 children,’ says Dienke. ‘There are two main cohorts: young children from pregnancy to seven years, and a teen cohort up to 16 years.’ That way, one does not have to wait years for the outcomes. The scale of the research project is exceptional, and unique for Europe. ‘The trend is to study larger and larger groups of people, in order to get more detail and more statistical power,’ says Dienke. This is important because child development is a complex interplay of many different factors; sometimes the effects are very subtle. You can only reveal them if you have a large dataset at your disposal.
But this data factory is not just about collecting as much data as possible. All the supporting processes are also important, from setting up the data factory properly beforehand, to publishing the collected data properly afterwards. At the YOUth study, this was set up with foresight and almost military precision.

Child development is a complex interplay of many different factors; sometimes the effects are very subtle. You can only reveal them if you have a large dataset at your disposal.

Car wash
The emphasis in the YOUth study is on social development and the development of impulse control: how do children interact with others and how do they learn to control themselves? In recent decades, this knowledge about early brain development has advanced by leaps and bounds. But this type of research is not without effort: for YOUth, a team of 40 employees is constantly working – finding parents with children to participate, scheduling appointments, hosting, supervising, and making sure the various research stations operate seamlessly. ‘The children go through a whole car wash,’ says Dienke.

For example, there is the room with the fake MRI scanner. There, children are prepared to take images of the brain in the real MRI scanner. Dienke: ‘The real scanner is somewhere else in the UMCU, but it is only available for brief periods, and we only have one chance.’ An old MRI scanner allows the children to practise lying still in a rather cramped tunnel. Dienke: ‘That includes some active teenagers, so it can be tricky.’
We then enter the eye-tracking room, where the children watch videos while an eye tracker registers what they are looking at. For example, when babies experience something unexpected, they look at it longer. This enables the researchers to deduce things about what babies remember or recognise.
In the EEG room, children are given caps with electrodes, and electrical activity in the brain is recorded. ‘Look at these, so funny,’ says Dienke, pointing to the smallest EEG cap. And then there is a room that only has cameras and directional microphones around a rug with toys on it. ‘This is where we film the interaction between parents and their children,’ says Dienke. ‘One of the most time-consuming jobs is coding the recordings: writing out what is said and done from moment to moment.’


Long-term thinking
Only this encrypted information may be released, unconnected to the subject’s name. Dienke: ‘The privacy measures are strict: researchers who want to work with the images go through a rigorous procedure.’
Interest in the collected YOUth data is plentiful: ‘The researchers who helped set it up were given priority, and have also already published their research,’ says Dienke, ‘but there are currently many requests for the use of this data, also from foreign researchers.’ With the data, scientists can answer various questions, some even unforeseen. Unexpectedly, for example, the study has provided an opportunity to track the social development of babies during and after the corona pandemic. Dienke: ‘What are the effects of the pandemic on development, and are those effects long-term or short-term? We can study those questions very well now.’

Eye for detail

Text: Bruno van Wayenburg
Photos: Ivar Pel

That the smallest – and seemingly unimportant – details can affect your research, university lecturer Roy Hessels (1990) knows all too well. He specialises in eye tracking – measuring what someone is looking at. For the YOUth study, he tests these measurement tools, and trains researchers in their use.

Eye trackers are getting better, cheaper, and easier to use. But using them correctly with children or babies remains quite a task, Roy knows: ‘In experimental psychology, we are used to adult subjects who you can instruct, and who can sit still. Things are a little different with a baby of a few months. In that case, it is especially important to do things slowly, but even then it does not always work out.’ Because the child is restless, for example, or because of technical problems, or – usually – because of a combination of the two.

Take, for example, the effect of eye colour. An eye tracker consists of a camera pointed at the eye along with an infrared light. ‘This produces a reflection,’ Roy explains. ‘The moment the eye moves, the pupil in the image shifts. The reflection also shifts, but slightly less than the pupil, because the eye is not perfectly spherical.’ Based on where pupil and reflection are relative to each other, the eye tracker software can figure out where the eye is focused.

‘In experimental psychology, we are used to adult subjects who you can instruct, and who can sit still. Things are a little different with a baby of a few months.’

‘But this often did not work as well with a light eye colour, such as blue eyes,’ Roy noted: ‘In infrared, blue eyes actually have a dark colour, and so the pupil is harder to distinguish from the iris.’ In other words, blue eyes provide less accurate data than brown eyes. This can affect the way you interpret the data. In a small group of participants, this subtle effect would have been lost in that of other factors that also play a role. For example, you might wrongly conclude that blue-eyed children are less able to concentrate than brown-eyed children. Roy: ‘We have recently started using an eye tracker for babies that is much less sensitive to this.’


Dienke Bos was managing director of YOUth until June 1st 2023. Roy Hessels is assistant professor at Utrecht University.

This article is part of a New Scientist special issue about the Consortium on Individual Development, that will appear in September 2023.

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