Jessica Leza, MA, MT-BC
February 18, 2021
What is the iso principle?
Ira Altshuler first used the term “iso principle” (iso is pronounced like ‘eye-so’) to describe a technique of using pre-recorded classical music to guide a participant through a change in mood. First the music therapist (MT) matched the music to the client’s baseline mood, then the MT changed the music gradually to inspire a corresponding change in mood.
More than 70 years later the iso principle has expanded to become a fundamental perspective in music therapy. It’s one of the first things taught to beginning MT students, and MTs have even been moved to proclamations such as “the iso principle is everything in music therapy!” The iso principle posits that thoughtful and intentional uses of the structural components of live music, such as tempo, rhythm, and melody, can serve as neurobiological guideposts that lead the body/mind to a healthy and optimally-regulated state.
For example, a person who is feeling severely depressed might respond to an exuberantly joyful song with a variety of negative reactions, but given music that matches their mood they might be able to process, express, and resolve that feeling and slowly transition to a more calm and content state. Alternatively, a MT might use the iso principle to help a hospitalized patient in the ICU moderate an elevated heart and respiratory rate.
The iso principle has many strengths as a therapeutic approach. It’s highly personalized not only to the individual, but the individual’s moment-by-moment experiences. In a world where people often feel like doctors throw prescriptions at them and walk out the door, a music therapist taking the time to employ the iso principle can be a mechanism for giving the client the space and time they need for change. Additionally, the iso principle is also something that non-music therapists can use as a tool in their own lives.
Breaking down the iso principle:
Entrainment, habituation, and autistic sensory differences
The iso principle works as a consequence of how our brains process music and the corresponding influence of music on non-musical brain function. Our brains have the potential to become entrained with the music, or to work “in sync” with the music. When our brains are able to process temporal aspects of music like tempo, meter, and rhythm then many parts of the brain begin to fire together. The pacing and stable timing cues of music help your brain execute motor planning programs in ways that make movements feel more fluid with less effort. Using music to help you exercise at the gym is a way to experience entrainment. In the first steps of applying the iso principle, the therapist meets the client where they are at in such a way as to promote this state of entrainment.
One of the factors that can impact your experience of entrainment, or your ability to become entrained, is the manner in which you become habituated. Habituation describes the tendency to get used to some type of external stimulus over time. If a shirt is uncomfortable at first but you get used to it, you have become habituated to it. If a strange noise makes you jump when you first hear it, but over time you stop being startled by it, then you have become habituated to it. Because music is a sensory stimulus, it is something that we can become habituated to. Like so many other expressions of our humanity, our ability to habituate to external stimuli can vary from person to person.
Studies have shown that Autistic people may habituate to sensory stimulus in different ways than non-autistic people. Sensory integration and processing differences may impact habituation, and this may in turn lead to atypical entrainment responses, particularly when these factors are not considered. Because Autistic people are vulnerable to meltdowns and shutdowns in response to overwhelming sensory stimulus in the environment, music therapists must be conscious of how music therapy procedures like the iso principle could actually be increasing the sensory overload of a distressed Autistic client.
Stimming as a Polyrhythmic Experience
Autistic people often move in unique ways and while the repetitive movements of many stims can be expressive and naturally become dance moves (#stimdancing), stimming most often serves the function of mediating sensory input in order to regulate the body/mind. The rhythm of many stims are instinctively calibrated to provide the type of sensory input needed to optimize functioning, and these rhythms are not necessarily direct and literal descriptors of the type of musical characteristics that best meet a client where they are at.
Said another way, just because an Autistic person needs the sensory input of rapidly bouncing their knee does not mean that they need music that bounces along at that same speed. Just because an Autistic person rocks or sways at a certain tempo to meet their needs doesn’t necessarily mean music at that same tempo best suits their needs. Why? Because music is an auditory (and tactile, and visual) experience, whereas bouncing your knee or rocking is a motor, vestibular or propriceptive experience – and someone’s auditory (tactile, and visual) sensory needs can be very different than their vestibular or proprioceptive needs.
If an autistic client is stimming in order to deal with an overwhelming sensory environment, and a music therapist tries to meet the client where they are at in their disorganized, unregulated, overwhelmed state by playing disorganized, unregulated, overwhelmed music, they are running the risk of unintentionally escalating the situation by increasing the sensory overload, and this could even push an Autistic person into a meltdown or shutdown. To use metaphor, If an autist’s cup is already full and the music therapist tries to pour water in, a mess is to be expected.
When an Autistic client is stimming to cope with an overwhelming sensory environment, addressing the problems in the sensory environment (e.g. dim the lights, reduce noice and conversation, unplug electronics, and provide access to healthy, self-directed sensory regulating activities) may reduce the sensory overwhelm. The iso principle guides MTs to do just the opposite – to interpret the external signals of sensory overwhelm as a baseline from which to add additional stimulus to the environment to promote entrainment and then change through the music.
There may very well be some type of music that could be beneficial in these situations, even if the iso principle doesn’t adequately describe that music. For example, in many cases a music therapist does not have the power to mediate an overwhelming environment, especially when sessions occur in shared spaces like a public school classroom or residential living space. In these cases, the MT might choose to use music in a controlled, stable, and moderate way so as to attempt to cover or mask some of the environmental sounds – while understanding that the autistic participant might still be able to hear those sounds over even with the most masterful musical camouflaging.
Alternatively, it could be the case that a client is stimming to help them handle a cognitive, social, or emotional load. In these cases it might be helpful for MTs to consider the rhythms of a bouncing knee or other stim as an improvised polyrhythmic solo that compliments the therapist’s own musical productions.
Here is the concrete, proactive tip emerging from all of this: the music therapist’s rhythms, tempo, and other musical characteristics do not need to directly correspond to the rhythm of a client’s stim. A bouncing knee does not translate directly to 8th notes on the E-string; instead stims can be polyrhythmic cues for the MT, who might find that for example a broad and stable tempo and meter is the best container for a ricocheting and chaotic stim. After all, there is no reason that clinical music has to always be in 3/4 and 4/4 – music therapists are not wind-up boxes chirping out pre-recorded hits. Find the space where your 3/4 is a fertile ground for your client’s 7/8 rocking and 14/8 flapping and 2/7 stomping.
To be clear I do propose that MTs consider an Autistic client’s stims as an embodied polyrhythm in order to potentially inform the musical decisions made for the characteristics and application of live music experiences, but also because this is a way to intentionally frame an Autistic person’s experiences as aesthetically valid. This brings us full circle to where we can follow the edict of the iso principle and authentically meet an Autistic person where they are at – but not necessarily by using the same strategies that work for non-autistic people, or not necessarily by using those strategies in the same way.