ISO principle

What is the ISO principle?

The ISO principle, also known as the isoprinciple, originates from music therapy and describes how music can specifically influence emotions. The term was coined by Schwabe (1978) in media psychology. It states that people choose music that corresponds to their current mood (Schaub 1981). Sad people often listen to melancholic music, while happy people choose cheerful sounds. The current state of mind therefore has a considerable influence on music preferences (Gembris 2005).

Influence of context and situation

Studies show that both personal and situational factors determine the choice of music. Activities such as housework, driving or a romantic dinner influence which music is perceived as appropriate. Schaub (1981) investigated the relationship between mood and music selection. He divided the test subjects into different emotional states: Joy, sadness, anger and serenity. His results showed that sad people were less likely to listen to happy music. Nevertheless, some deliberately chose happy music, which calls into question the general validity of the ISO principle (see Mood Management Theory). However, Vorderer & Schramm (2002) largely confirmed that happy people prefer happy music and that many sad people listen to sad music.

Personal emotions and music selection

Behne (1986) added that only people who are satisfied with their current emotional state choose music according to the ISO principle. He distinguished between desirable and undesirable moods. Mayer and Gaschke called this phenomenon metaemotions – the conscious perception and regulation of one’s own feelings through music (Schramm).

Differences according to age

Schramm & Vorderer (2002) found that age plays a role in the choice of music. While adolescents and middle-aged adults have similar music preferences for positive emotions, there are major differences for negative emotions. Young people often use music to process or intensify their feelings. Older people are less likely to listen to music when experiencing negative emotions, especially anger, or to specifically choose uplifting sounds. These results indicate that music preferences change in the course of life (Gembris 2005).

Individual choice of music

Not only do different people choose different music despite being in a similar mood, one and the same person does not always choose the same music in the same mood. The choice depends on various factors: Mood, personality (e.g. gender, education, age) and external influences.

ISO principle and equalization principle

The ISO principle states that people listen to music that matches their current mood. However, studies show that this is not always the case. Sometimes the compensation principle comes into play: people consciously choose music to change their mood. In positive situations such as joy or romance, they usually prefer music that matches their mood. In monotonous activities, contrasting music is often used to relieve boredom. In the case of sadness or anger, behavior varies: Some intensify their emotions with appropriate music (ISO principle), others lighten their mood with contrasting music (compensation principle).