It has been proposed that patients who suffer from mood disorders benefit from music listening according to the iso principle. The iso principle in a therapeutic context means that patients initially listen to music which matches their current state, and afterward listen to music which expresses a desired state. However, experimental evidence in this patient group is lacking. Thirty-eight patients with mood disorders were included. They were randomly assigned to one of two experimental groups: the iso-group listened to music according to the iso principle with a sad song first and a happy song afterward; the compensatory-group listened to music according to the compensatory principle with two happy songs in sequence. In the iso-group, positive affect decreased after the sad song, and increased after the happy song. In the compensatory-group, positive affect immediately increased after the first happy song, and did not further increase after the second happy song. Negative affect decreased in both groups. We conclude that music listening to the iso principle as well as the compensatory principle are suited for affect regulation in patients with mood disorders. For therapeutic purposes, the iso principle may be used to work with the affect-enhancing effect after low positive affect.
Starcke et al. (Sun,) studied this question.