Nijboer tried to find out what happens in your brain when you multitask. Many researchers have already looked into this, but a clear answer is yet to be found. ‘You multitask without thinking about it’, says Nijboer, absent-mindedly petting his cat. ‘But in your brain, many things are occurring, so there has to be some kind of logic to it.’

In the scanner

In order to figure out this logic, Nijboer placed test subjects in an MRI scanner. While inside the scanner, they had to carry out various tasks, such as counting the number of high-pitched sounds, following a dot on a screen, or remembering the letters they saw on a screen. In the meantime, Nijboer scanned their brains. ‘You could see which parts of the brain were active during the tasks’, he says. ‘And by placing the scans over one another, we were able to predict which tasks would be able to be done together and which would not.’

‘Your working memory can only focus on one thing at a time’
The predictions proved to be right: counting high-pitched sounds while following a dot at the same time was easy because each task used a different area of the brain. But if the test subjects had to remember letters as well as count the high-pitched sounds, it did not go well. ‘Your working memory can only focus on one thing at a time’, explains Nijboer. ‘And it also goes badly if you have to do two visual, motor or auditory tasks at the same time.’

A little distraction

Multitasking can thus cause your performances to deteriorate. Nijboer also saw this during an experiment using a driving simulator. Subjects who had to read a text on a tablet while driving performed very poorly. Nijboer: ‘Driving primarily uses the visual area of the brain. If you have to do another visual tasks alongside this, it all goes wrong.’ You are better off setting your mobile aside.

However, a little bit of distraction doesn’t do any harm. The subjects in a simulation who listened to a radio show while driving and had to answer questions about it drove better than those who had to drive without sound along a boring, straight stretch of road. ‘If you don’t have any distraction, you daydream and create your own distractions’, says Nijboer. ‘That is almost as bad as visual distraction.’

It is thus best to put the radio on or have more people in the car, Nijboer thinks. He does not expect this advice to be taken on board nation-wide, but it is certainly a nice starting point for further research. And if they are working on multitasking in traffic anyway, he has another idea: ‘Maybe we should also look at all the cyclists with their mobiles in their hands. We can surely come up with some helpful advice for that.’