A skin sensor that measures your physiology together with software that knows its way around your music library: together these produce a device that can steer the user’s mood right towards the mood in which he or she wishes to be. This is the result of research by Marjolein van der Zwaag, who will be awarded a PhD for this on 26 April 2012 at the University of Groningen. She developed this ‘affective music player’ on the basis of research into the link between music and mood, for example in car drivers. Such a player could potentially lead to less aggressive driving.
Music is an ideal way to change your mood, whether you want to feel angry, energetic, sentimental or relaxed. However, listening to the radio only helps to a certain extent because no matter how carefully the tunes on a music station have been selected, every few songs one will come along that puts a damper on that mood. This is why people prefer to put on CDs or choose music from their own iPod. ‘The trouble is that their collections are often so extensive that they can’t see the wood for the trees,’ says Van der Zwaag. ‘They really have to think about, and then find, the right song to take up where the other one left off and direct them to a certain mood. They might be able to do this for a few songs but not for hours on end.’
Van der Zwaag used two physiological variables to study the effect music has on our mood: skin temperature and skin resistance, the level of electrical conductivity of the skin, which varies according to moisture content. The former says something about how positive the listener is and the latter about how energetic he is. Van der Zwaag says, ‘I then define each mood in terms of these two variables. This is a simplification of course, but it is possible to place all emotions on that coordinate system. If listening to Dutch singer Jantje Smit causes the listener’s skin temperature to increase and also makes his skin moister it means that he is becoming more positive and energetic, or in other words happier.’
Skin temperature and skin resistance can both be easily measured with a sensor, on a wristwatch, for example. This is how the ‘affective music player’ receives its information about the listener’s mood, completing the device. The essence of this is that it follows the user’s orders. If he is feeling melancholy and wants to stay that way he will get, without having to search at all, a lovely mix of melancholy music that will bring his skin temperature and skin resistance down. Van der Zwaag acknowledges that this does mean a bit of homework for the listener, ‘To start off with, the system does not know the effect a song will have on you. At that point the device can assign an initial positivity and energy value to the tune, on the basis of musical elements such as tempo. Another option is for the user to assign initial values to the tunes when he adds them to his music player according to how positive and how energetic they make him feel. The good thing is that these values can shift. If a cheerful song no longer has the same effect because you have heard it too often, the device registers this from your physiological reactions. The prediction that the device makes about the direction a tune will send your physiology, and therefore mood, is updated each time you have listened to the tune.’
Car drivers received special attention in the research, because after all they do not have a CD rack on the wall and cannot continually be searching their iPod either. Van der Zwaag tested a prototype of the device on car drivers as well, and it did prove possible for them to become calmer if they just ‘ordered’ the right mood. Van der Zwaag took as the basis here what the drivers themselves said they found to be relaxing or stimulating music. ‘A study of this had already been done, but then it was the researchers who decided which music was happy. This meant that the results were less unambiguous than what we have found now: music can push your mood in the desired direction for a longer period. This could possibly prevent accidents but also stress behind the wheel.'
Van der Zwaag did her research while working at the Brain, Body, and Behavior Department of Philips Research in Eindhoven. They are very interested in her findings but do not have any concrete plans as yet to start development on the device themselves. The results of her research could also have a broader application with, for example, the use of music to calm people during medical examinations.
Marjolein van der Zwaag (Sneek, 1984) studied Artificial Intelligence in Nijmegen and has worked at Philips Research in Eindhoven since 2008. The title of her thesis is ‘Music directs your mood’. Her PhD is in Behavioural and Social Sciences and her supervisor was Prof. K.A. Brookhuis. Her co-supervisors were Dr J.H.D.M. Westerink, Dr D. de Waard and Dr L.J.M. Mulder.
Contact: Marjolein van der Zwaag, tel. 040-2748372, e-mail: mvanderzwaag gmail.com
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