Music fans' emotions could be used to help them find new songs online, according to research at the University of Strathclyde.
A study of 150 music videos made by U2 fans uncovered a range of methods, both visual and musical, used to convey emotion, through location, style of music and video content.
Dr Diane Pennington, a Lecturer in Strathclyde's Department of Computer and Information Sciences, carried out the research. She said: "Although music holds no emotion in itself, it can elicit very deep emotions in listeners and performers."
The videos were covers of U2's Song For Someone, from their 2014 album Songs Of Innocence. They were made and posted on video streaming website YouTube, after the band invited their fans to create their own clips, which would "make (it) your song."
The research found that the videos, and viewers' responses to them, were highly individual but often also social, with shared emotions creating a sense of community.
It also found that such emotions could help to inform searches, recommendations and playlists in online music providers.
Dr Pennington said: "The emotion music evokes is the main reason people listen to it and many would like to be able to search for music videos that meet an emotional need, such as a desire to be cheered up.
"However, information retrieval systems, such as those used in video streaming sites, don't currently support this well. To advance these systems, new systems need to be envisioned that go beyond traditional keyword-based or subject-based queries and process information requirements in new ways.
"I chose the Song For Someone clips as a case study after U2 called for fans to make them. This was because it would be a rich source of information and because, for their fans, U2's songs and concerts are highly emotional; this is reflected in the content of the Song For Someone clips and the reactions they produced.
"Many of the cover versions were personalised by people recording their own versions in their houses or bedrooms, or including images of their loved ones. Others signified their devotion to U2 by using their original version to accompany the clip or by including U2 paraphernalia, such as t-shirts, posters and photos.
"Emotions are difficult to define tangibly and describing them in a way which could benefit information retrieval presents a challenge. However, this research could inform commercial music service providers on how they might include emotional factors in their recommendations and automatically created playlists.
"Allowing retrieval system users to search, browse and retrieve by positive emotions could also have a contribution to make to music therapy."
Dr Pennington's research has been published in the Journal of Documentation.
Explore further: Facial expression more important to conveying emotion in music than in speech
Diane Rasmussen Pennington. "The most passionate cover I've seen": emotional information in fan-created U2 music videos, Journal of Documentation (2016). DOI: 10.1108/JD-07-2015-0086