Stroking their arm 50 times may help a patient. Who benefits the most from such treatment?
Some people experience problems in the way they perceive their body, for example after brain damage. They may, for instance, experience that their arm no longer belongs to their body. They may benefit from slow, affective stroking, as a result of which they may perceive their limb as part of their body again. In the future, we may find that this treatment also works for people with other forms of body perception disorders, such as in psychiatric disorders or after physical injuries. It is important that the stroking is perceived as pleasant. Slow, affective strokes are being processed by other nerve systems and ensure a higher level of body perception than quicker ones that feel less pleasant. This is the outcome of a study making use of the ‘rubber hand illusion’, an experiment in which the body perceptions of healthy people are being manipulated. The participants are shown a rubber hand that is being stroked in synchrony with their own hand, which they are unable to see at that moment. In this way, the participants get a sense as if the rubber hand is their own. This feeling becomes stronger when the stroking is slow and pleasant, rather than quick and unpleasant.