Involuntary to intrusive: Using involuntary musical imagery to explore individual differences and the nature of intrusive thoughts

People frequently experience musical imagery-times when music plays in awareness in the absence of immediate environmental music. Although people may intentionally bring songs into awareness, songs often enter the mind without conscious volition. Sometimes an episode of involuntary musical imagery is brief, with the song simply passing through one's thoughts. Other times the song may become stuck in one's head. Having a song stuck in one's head is an involuntary thought that most people have experienced and that many people experience frequently (Bailes, 2007; Beaman & Williams, 2010; Beaty et al., 2013; Halpern & Bartlett, 2011; Hyman et al., 2013; Kvavilashvili & Mandler, 2004; Liikkanen, 2008, 2012a, 2102b; Williamson et al., 2012). Our goal is to use involuntary musical imagery as a means of studying involuntary and intrusive thoughts more generally: to understand the reasons songs return to awareness, investigate individual differences in involuntary thoughts, and explore the features that lead some songs to feel intrusive when they invade one's awareness.In several recent studies, researchers have described the experience of having a song stuck in one's head, developed experimental methods to explore the experience, and investigated individual differences related to the frequency of the experience. Some of these findings have disproven general beliefs about the stuck song experience. For example, the general social belief is that having a song stuck in one's head is unpleasant; either because annoying songs are more likely to become stuck or because the experience exemplifies the failure to control the contents of consciousness (Kellaris, 2003, 2008; Levitin, 2006). This may be why the general term for the experience is an earworm-an obnoxious song that burrows into the mind and refuses to leave. This general belief is, however, incorrect. Although disliked songs do sometimes get stuck, people generally report liking the songs in their heads and find the experience to be pleasant (Beaman & Williams, 2010; Beaty et al., 2013; Halpern & Bartlett, 2011; Hyman et al., 2013; Williamson et al., 2012).These recent findings also suggest that when a song is stuck in one's head, the song is generally repetitive in two important aspects. First, only a small part of the song, typically the chorus, repeats in awareness (Beaman & Williams, 2010; Hyman et al., 2013; Liikkanen, 2012a). Second, the song returns repeatedly to consciousness (Hyman et al., 2013). A song may start replaying mentally, temporarily leave awareness, and then return later. Hyman et al. (2013) argued that both of these repetitive aspects of involuntary musical imagery reflect Zeigarnik (1967) effects, such that unfinished thoughts stay active and return to memory and consciousness. This occurs because people may have a song start mentally replaying, but are generally unable to complete the song. Instead, when people remember a song they can reach the chorus but fail to leap across the gap to the next verse (Hyman & Rubin, 1990; Rubin, 1995). This may cause the chorus to keep looping. Consistent with a Zeigarnik effect for unfinished thoughts, Hyman et al. (2013) found that if a song starts replaying in someone's head after listening to it, that song is more likely to return over the ensuing 24 hours than if the song did not start mentally replaying immediately after exposure.The onset of involuntary musical imagery generally reflects recent exposure- either hearing the music or being exposed to some other stimulus that brings the song to mind (Hyman et al., 2013; Kvavilashvili & Mandler, 2004; Liikkanen, 2012b; Williamson et al., 2012). For example, the last song in a set of music is the song most likely to become stuck in awareness (Byron & Fowles, 2013; Hyman et al., 2013). Recent exposure may explain why people frequently report Christmas songs playing in their heads during the holiday season (Halpern & Bartlett, 2011; Kvavilashvili & Anthony, 2012). …