You might be very familiar with the word hallucination which you may usually associate with images or pictures – in short, visual stimuli. When we say visual hallucinations, there is false perception of sight; it is the perception of an image or an event as if it is “actually” happening when in fact is not. Example would be seeing a person in front of you when there actually is none. Because of familiarity with the phenomenon of visual hallucination you yourself might say that it is not hard to imagine people “seeing” things. You may be all too familiar with this kind of hallucination, but did you know that there are also other kinds of hallucinations involving our other senses? Yep! You read it right. Hallucinations can also occur in auditory (sounds), gustatory (tastes), and even tactile (touch) forms! For this blog entry, we will be focusing on one form, auditory hallucination. Today, I will be introducing you to the different kinds of auditory hallucinations, specifically musical hallucinations (or the experience of hearing music when there really is none playing) and their distinctions.
There are different categories of musical hallucinations and some of these categories aren’t really hallucinations. Sounds confusing? Sounds acceptable because for one hallucination in terms of audition or sound perception is a flexible term. It can refer to the whole notion of hearing things despite the absence of real sound, or the specific category of auditory hallucination that is related to neurological and psychological disorders. To avoid confusion, researchers have used (and for the sake of smooth discussion, we will be using) the term musical imagery to refer to the encompassing notion of “hearing” despite the absence of sound or music and musical hallucination for the more specific category. Let’s get into the details.
What is interesting about the phenomenon of musical imagery is that it occurs in a lot of forms in different people and these forms are seen as being in a continuum based on two categories- specification of vividness and perceived sound source. Specification of vividness refers to how imagery-like or real the perceived sound or music is. Meanwhile, the perceived sound source refers to whether a person perceives the sound as coming from inside his head or from the outside/environment. We shall discuss each form and point out which end of the spectrum they are in for both categories.
One form that you might be familiar with is what Hemming and Merrill (2015) termed involuntary musical imagery (INMI) or earworms. This refers to the phenomenon of music coming to mind without deliberate attempt. Sounds familiar? Right now you might be thinking of a similar experience that is commonly described as LSS or the Last Song Syndrome. You get LSS when the last song you heard gets stuck in your head on repeat even if you do not intend to recall it. Yep! You can think of LSS as a specific example of INMI. As you might have experienced having LSS often, it is not hard to believe that involuntary music imagery is the most common form of musical imagery. This form of musical imagery is not associated with any kind of pathological conditions or any psychological disorders. Meaning, it is normally experienced by the healthy population. In terms of the two categorical spectra, INMI is on the “imagined” end of the specified vividness spectrum, and on the “internal” end of the perceived sound source spectra. In short, earworms are imagined and those experiencing it perceive the sound as coming from inside their heads.
Based on your experience, having a song stuck in your head for a few minutes isn’t exactly causing problems for your attention or everyday functioning, right? But what if instead of songs playing in your head for only a short period of time, they persist in your head and there is just no way of getting them out or stopping them from continuously playing? Unfortunate as it may sound there is such a thing as Permanent Involuntary Musical Imagery (PINMI). As was described, it’s like having INMI but more often and happens for more extended periods of time. Some even have it worse as the experience occurs 24 hours in a day. Hemming and Merrill (2015), in their study, have cited the story of one person, Subject A, as a case of PINMI. Subject A is a 36-year old DJ who is suffering from lingering sounds after spending nights in the clubs. He has been experiencing PINMI for 7-8 years. He describes and is aware that the music is clearly inside his head. Based on subject A’s case and in reference to the specified vividness and perceived source spectra, PINMI is near but not on the “imagined” and “inside” end of both spectra.
The following forms of musical imagery are very tricky. The first of the two is termed musical hallucinosis. The name sounds a lot similar to musical hallucinations but we should be careful not to mistake one for the other! People with musical hallucinosis perceive music in the absence of actual music and is still able to maintain insight or the understanding or awareness of the person of his condition. Going back to our two categorical spectra, hallucinosis is right in the middle of both. The case is such because although the imagery in hallucinosis is relatively “more real” than that of INMI and PINMI, the presence of insight keeps the person aware that the perceived music isn’t actually real. This balances the imagery-likeness and realness of the perceived music. Insight is what also reminds the person that although t seems like the music is coming from an external source (e.g. a musical instrument playing0, the sound really is just inside his or her head. Meanwhile, in comparison to simple INMI, musical hallucinosis is associated with hearing deficits (e.g. hearing loss) and is even thought to be caused by such deficits.
The last form, musical hallucinations, is very similar to musical hallucinosis except for the lack of insight. Another distinguishing characteristic of musical hallucinations from hallucinosis is in terms of the vividness of the perceived music. As you might have guessed, musical hallucinations are on the other far end of both spectra. Musical imagery in hallucinations is perceived to be real and coming from the external environment. This condition is often associated with psychotic disorders or conditions of lost contact with reality caused by severe impairment in thoughts and emotions. People experiencing musical hallucinations therefore “hear” music as if it was actually being played by some external source (e.g. musical instrument or audio device as in mp3 players).
To facilitate understanding, Hemming and Merrill (2015) have summarized information about INMI, PINMI, musical hallucinosis, and musical hallucinations in the following table. The table shows us where in the spectrum of specified vividness and perceived sound source these four forms of musical imagery fall.
Hopefully, learning about musical imagery did not just give you evidence and a scientific explanation of what LSS is. Hopefully this blog also made you aware of the existence of musical imagery and its forms, and shed light for your understanding of the phenomenon.
Hemming, J., & Merrill, J. (2015). On the distinction between involuntary musical imagery, musical hallucinosis, and musical hallucinations. Psychomusicology: Music, Mind, And Brain, 25(4), 435-442. doi:10.1037/pmu0000112
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