Music that expresses more emotion than that felt by listeners is likely to be unpopular or "daggy", according to new empirical research.

Published in the current issue of Psychology of Music, the research reveals that music is considered more enjoyable when its emotionality closely matches listeners' degree of emotional response.

"The smaller the gap between people's 'felt' emotion and music's 'expressed' emotion, the more they enjoy it," says the study's author, Emery Schubert.

A University of New South Wales music psychologist, Dr Schubert refers to this difference as the 'Differential Affect Gap' - or "DAG factor".

"The DAG factor is a new quantitative predictor of people's emotional liking for music," according to Schubert, who says it could explain why some people dislike Barbara Streisand's music.

Dr Schubert has done prior research revealing that people who expressed dislike for Streisand's music rated it as having a high degree of emotionality compared to their own emotional response.

Until now, people's like or dislike for particular music has been viewed by some social psychologists as a proxy for belonging to a particular social or age demographic. According to this view, people of one sub-group (like teenagers) will express dislike for the music of a non-peer group (like parents), as a way to establish and maintain their sub-group identity.

It's an idea that has been used to control group behaviour. For example, young "hoons" were successfully discouraged from meeting at a car park in a Sydney suburb by playing Barry Manilow music through loudspeakers. (Full story)

However, this social psychological phenomenon is difficult to measure. By contrast, the Differential Affect Gap measure may provide new insights into understanding how people relate to music.