In Pursuit of Understanding

Emergence is a really interesting phenomenon. Emergence is when the system does things on the systems scale that you would not be able to predict from the components and how they interact. Let’s take the human brain: it is a complex system. The entities are neurons (nerve cells). They’re connected to each other. They send signals to each other. They are all very simple, and in fact you can write down mathematical equations which are quite good representations of what neurons do. But, now you connect a huge lot of them together and out of this comes things like consciousness – we are actually aware of ourselves and our surroundings in this rather big, big way. There is nothing in the structure of a neuron that says it’s got to do that, that (in a sense) the neurons don’t know about that; yet cognitive scientists would say that this is not some extra/external thing that is wonderfully being imposed by some[thing] supernatural…You can understand little parts of the brain, but even that is quite difficult… All of the evidence is that, somehow, what all of the wonderful things that the brain does – like language, like vision, hearing, taste, our senses, our movement – all of this happens by neurons exchanging electrical and chemical signals along the network. The network changes as we learn. The network changes as we grow from babies to adults… What it (the brain) does may not be as complex in itself as all of the underlying details. When I am talking to you, we could describe the whole conversation in ordinary language very, very clearly. If I tried to find out and write down what all of the nerve cells in our brains were doing when that happened it would be impossible to describe.

Once that emergent is in place, there is an additional dynamic. The emergent has 2 effects, it both constrains certain behaviors of the interacting entities (because there are existing systems in place) while, at the same time) it opens up new possibilities. And that makes it a very, very dynamic process. It is not only a bottom-up process, it is also a top-down process and the whole thing is changing very dynamically the whole time.

Recently on Facebook, I posted (on 2 occasions) a link to a podcast from In Out Time with Melvyn Bragg  on the subject of complexity. In a related post, I wrote, “Physical Therapists continue to fail to addresses patient’s complaints of pain because we have – and continue to – insist on creating complicated explanations and models that are necessarily insufficient to understand our patients complaints. When will we learn? The problem is one of complexity, not complicatedness.”

A few years ago, I would have viewed such a remark to be an exercise in semantics. Today, I have a better understanding of how the words we use necessarily shape how we think and how we interact with our patients. As a result, I would like to take this opportunity to review some of the important ideas that I took away from this particular podcast and how they may relate to physical therapy practice – especially when providing care to patients with painful problems.

So, how is the idea of complexity related to physical therapy?

Complexity is a point of view about systems in which large numbers of agents or entities which interacting according to fairly specific rules. The idea is to set up a mathematical model to represent that kind of system in a very accurate way.

Sound familiar? How about that part of us that is 25,000 cm² in size and comprised of 100 Billion neurons in the brain alone, each with 1000 to 10,000 synapses. It is that part of us that – if we lined it up each piece from end to end – would be approximately 600 miles long.

Yes, I am referring to our nervous system, arguably the most complex thing that we, as humans, have ever studied (or ever will). Thus, to be clear, all of our conscious experiences and everything that makes us who we are is necessarily derived from the most complex of complex systems. If you are a clinician working with patients in any field of medicine, you must appreciate the complexity of the system with which you are interacting and embrace the idea that you indirectly become a part of it.

Of course, complexity goes beyond neuroscience. The science and study of complexity applies to a variety of subjects from how birds flock, to metropolitan design, to economies, to weather forecasting and medical management. For instance:

From a more practical point of view, [an understanding of complex systems] would allow us to be able to do things like manage an epidemic better. This is a major problem. You know that there is a disease coming…but what strategies should you use as a government to try to contain the outbreak better? So if you have mathematical models that are good enough, you can try strategies out on the models. You can do experiments on the models which you cannot do on the real world and you can maybe learn how to deal with these problems.

So, scientists are using complex systems models in an effort to try to understand a variety of phenomena in our world. But how does this apply to physical therapy, specifically?

Reframing The Therapeutic Encounter

Historically, physical therapy has been a field of linear thinking: an individual seeks care for a painful problem; the physical therapist’s responsibility is to provide the patient with an assessment including a variety of tests and measures that are historically used to find a specific offending structure or underlying problem that should be predictably managed with a specific routine or plan to alleviate the patient of their primary complaint. The patient presents with ‘B’, the therapist provides ‘C’ and the patient is supposed to be rehabilitated back to ‘A’ again (more on this later).

Of course, the patient does not always get back to ‘A’, so the therapist continues to pursue a variety of reductionist and linear clinical models in an effort to try to find the one that will ‘work’ with the patient in question. Sometimes the therapist ‘gets it right’ on the first try, often they don’t. Perhaps, it is time for the entire field of physical therapy to approach things differently.

Complex systems science is a new way of thinking. It contrasts with a 19th century view of science which is a lot more mechanical and deterministic. In complex systems, the dynamics of the system generally emerges from the interaction of the parts and their agents. And that is not necessarily predictable in the way that traditional science thinks that it should be. Complex systems science is very much computer enabled, because we have to compute the interactions of the agents and find out the way the system dynamics are evolving… Our outlook has changed with regards to what ‘prediction’ means. In the 1960s, the meteorologist Lorenz discovered that there are systems that are sensitive to initial conditions so that a slight change in the conditions at one time can mean the system can diverge greatly at another time. So, our expectations of what we can predict in physical systems has changed a lot in that time.

Let’s state this clearly: only with computer models, running a variety of simulations with an ever-expanding number of initial conditions, could a therapist possibly discover the possible outcomes of their interactions with their patients, be they the environment in which the patient receives their care, how the therapist is dressed, the words/tone that are used in communicating with the patient, the location where the therapist places their hands and how firmly (or softly) they place them, or the expectations that the patient or therapist may have at the outset of a clinical encounter. If at any point in their career, a physical therapist feels that they have seen enough patients to recognize patterns of how they may necessarily be impacting an individual’s experience (B + C → A), they are fooling themselves.

I am not saying that they are poor clinicians, I am only pointing out that the science is informing us that their interactions with their patient’s do not yield results as predictably as one might often think that they do, and even if they are fruitful, they are unlikely to be beneficial in a way supported by conventionally linear thinking. The models that therapists use for thinking need to change. They need to embrace the science of complexity.

Butterfly Effects: Missing Flights, Wild Turkey and 4th ribs

[In a complex system,] if a butterfly flaps its wings, you could potentially have a storm form somewhere that wouldn’t form somewhere else… Like many things in systems science, metaphors are used and misused. [And while the butterfly effect metaphor is often misused], it is true that changing initial conditions would change the outcome…For example, if you wake up 5 min. late, you might miss the bus. If you miss the bus you might miss another connection and you might miss your flight. So something very small can end up in a very big change.

It would seem that, in many instances, therapists benefit from the existence of the butterfly effect, but neither appreciate or understand it. Even still, in many instances, they rely on it. Recently, I heard a podcast with a researcher/clinician who argued that distal lower extremity pain could be understandably effected by the application of manual forces to the 4th rib in the thorax, correcting for less than optimal alignment of the thoracic cage. The individual was able to – biomechanically – account for how this might happen and it sounded incredibly impressive. As a matter of fact, it was humbling to be reminded of how little one knows; such was the case for me as she so easily and quickly rationalized through the anatomy/kinesiology on her way down the chain from thorax to foot. Of course, the clinician admitted, 2 patients may present with the same complaint in the lower leg and the same positive finding (with palpation) in the thorax, but only one may be a ‘responder’. The pain may persist in one individual, while it is reduced or abolished in the other.

How can that be so? If the biomechanical reasoning is so sound – and it is – how is it that the pain persists?

There are things that are – for all practical purposes – unpredictable…As the system’s behavior diverges, you get a kind of horizon beyond which prediction doesn’t make any sense….We need to make a very clear distinction between complex and complicated, because we often confuse the one for the other. Complicated is very much a machine-type system. In a complicated system, we can design, we can predict its behavior, and we can control its behavior. We can do none of these things with a complex system…

Let’s look back to the example of the bus from the podcast: What if, on the same day that you woke up 5 minutes late, there was also an accident on a nearby highway, which backed up traffic down the on-ramp 3 blocks from your bus-stop. Granted, you had to wait for the next bus, which was later in the commute, so there was heavier traffic, but did you realize that the traffic was actually heavier and slower more than is typical, because of the accident? Did you realize that the accident had involved a tractor trailer whose contents were spilled all over the highway and took an inordinately long time to clean up? Did you know that this accident (and the traffic delays as a result) was so bad that you would have been late for your flight even if you had woken on time? Of course, you don’t know any of that listening to your iPod instead of the traffic report on local radio. While you are jamming out to Pearl Jam angrily blaming last night’s extra shot of Wild Turkey for your tardiness, you are unaware that a truck driver spilled coffee on his lap 5 miles from your home and you are going to miss your flight as a result.

When entities interact, they create complex behavior, and they start connecting with each other. It is not only a matter of connection, it is also a matter of interdependence that then arises from that connectivity…A lot of complex systems you can actually represent the connectivity as a kind of network (paraphrase) drawing all the entities and all of the entities that they make contact with along that network. The structure of the network effects very strongly the speed of transmission of impulses or signals along the network and where they spread to. If highly connected, one entity can impact a large number of other entities…We often assume that connectivity is the same over time, but it is not. The quality and intensity of connectivity varies all the time and we need to understand that connectivity is not the same over time. It does vary.

What if you knew a the coffee-shop hostess had mistakenly not sealed the truck driver’s coffee cup completely? What if you knew that it was her first day working with a cast on her non-dominant left hand that she broke over 2 days ago when her 60-pound mongrel unexpectedly chased a stray cat while on an otherwise pleasant walk, knocking her to the ground?

How could you imagine that a cat garnering the attention of a dog (45 miles away) would eventually lead to you missing your flight 48 hours later? You couldn’t, and that is the point.

Waking up 5 minutes late is the positive finding at the 4th rib. Sure, waking up on time might help. So too might placing your hands on their thorax. But even if there is no accident, you arrive to the bus on time, the woman doesn’t break her wrist, the driver doesn’t spill his coffee, there isn’t an accident on a highway, the bus driver gets you to your connection on time and that bus driver gets you to the airport on schedule…do you get to take credit for all of that, because you had the resolve to get up on time despite that ill-advised shot of Wild Turkey? No, you get to breathe a sigh of relief every morning when things just happen to work in your favor. Likewise, a physical therapist should breathe a sigh of relief when their patients improve, not pat themselves on the back when the patient is “rehabilitated”.

What “Rehab”?

Why the “scare quotes” around “rehab”? According to Merriam Webster, rehabilitation is most often defined as, “to bring (someone or something) back to a normal, healthy condition.” This would hold true in the traditional model of physical therapy care that I referenced earlier: B + C → A. It is clear that, on one hand, there are far too many variables to make this an accurate account, but I want to explore the notion of physical therapy, even in a complex system, getting a patient ‘back to where they were’ before their injury.

Very often in these networks, you’ve got all types of feedback loops and they interact, so there is intense complexity to these networks and the loops; that is one of the reasons why systems that are (locally) easy to understand become very complicated when you look across an entire network. We also need to differentiate between positive feedback and negative feedback. In positive feedback, there may be multiple equilibria. We need to distinguish that from negative feedback, which closes the gap between the actual and the desired; that has a single equilibrium point.

The initial primary complaint of a patient is very rarely of a specific dysfunction (i.e. something is wrong with my L3-L4 facet). No, their primary complaint is more often related to their general dysfunction. They walk in and say, “My back hurts.” For decades, traditional care involved the therapist using a complicated reasoning model to discover an underlying dysfunction that would predictably respond to intervention, bringing the offending structure back into equilibrium. Again, sometimes it worked, often it did not. This, is because even if the therapist was able to restore health to a tissue or optimal movement to the perceived offending structure, they were working from a false premise.

Often, in complex systems, we assume an equilibrium point and we make wrong assumptions. We assume that (as in a simple mechanistic system, with a single equilibrium point) that if we apply the right amount of correction at the right time, it will actually go back to its equilibrium…We cannot do that with things that are complex.

While the bones, joints, muscles, ligaments, fascia (etc) are all parts of an admittedly complicated mechanical system, they are but pieces of a marionette**. It is not the marionette that feels, senses, emotes and motor plans, but instead the puppeteer. It is the puppeteer’s own complex nervous system that brings the puppet to life. It is the nervous system of the puppeteer that brings about the marionette’s expression, its movement. Most importantly, it is always the puppeteer – never the marionette – that feels pain. All that the puppeteer is, with all of his complexity – all of his experiences since he was born, his expectations, his fears, his motivations, his desires – is screaming in pain behind the curtain while the therapist provides treatment to a puppet on a stage.

Meanwhile, the therapist is trying to “get the patient back” to how they were before – to bring the patient’s experience back into equilibrium. This, however, can never be the case.

You cannot go back to what existed in the past. There is no reestablishing a position, because the system – by exploring new alternatives and evolving – will attain a different state. One equilibrium shifts, however, there are multiple equilibria at one time, not a single one. That is the key thing here. Or there may be no equilibrium at all; the system might be in a state of constant change. In traditional science, you have a formula. For example, if you fire a cannon ball, you can predict exactly where it is going to land in when it is going to land. In most of the systems we call complex, we can’t do that with any degree of certainty.

While the therapist has extensive knowledge of biomechanics and is often indispensable in the helping the patient regain once lost mobility and strength, the primary job of the physical therapist is to guide a nervous system in such a way that it is able to discover how to move comfortably and efficiently once again, using neural circuitry in a way that it has never done before, reshaping the patients neural pathways, creating new neurotags. What we do as therapists is more wonderful than we give ourselves credit for…when done right, it is a beautiful thing – even though we don’t have control.

Where do we go from here?

I am not necessarily advocating for therapists to necessarily change what they do in the clinic, but I am insisting that they approach each encounter with the awe, humility and respect that a complex system should engender, appreciating that their job is not to get a patient “back” to where they once were, but to bring them forward to where they want to be. If the therapist is able to maintain that perspective in each encounter – with every patient – they can come to the realization that they do not rehabilitate so much as the educate.

We must understand that what therapists say and do with their patients at any moment not only impacts them today, but also tomorrow. Therapists create explanations and expectations, nocebo and placebo; they create a context through which a patient experiences each and every pain for the rest of their life. It is of utmost importance that the physical therapist appreciate that responsibility.

[It must be made clear that (even when computer models are utilized)] they are unable to predict the results of the system once and get the answer. What happens is you have to run the system many times, because most of these systems are sensitive to initial conditions. So through the computer simulation you get an understanding of the space of possibilities. But initial conditions have their own dynamic, [called] path dependence, which is [to say] what happens in a system depends on his history.

Every encounter, everything that a physical therapist says and does must be presented to a patient with the understanding that the therapist is introducing a new initial condition to a complex system. Every time a therapist provides the patient with a complicated explanation for an output from a complex system, they fall woefully short of providing appropriate care for their patient. They conflate correlation for causation. They reinforce their own cognitive biases and poor pattern recognition while instilling those same biases in their patients. They change the foundation on which the patient builds the rest of their life, and the lives of their patient’s friends, families and acquaintances. The responsibility of the physical therapist is not only to get their patient better, but to prepare that individual, with their complex nervous system for the rest of their life. The patient should walk away from a clinical encounter not with the notion that the therapist ‘fixed’ them, but that the therapist helped them fix his or her-self.

Complexity is ordinary, it is a different way of thinking into a science that is quite young, so we don’t have answers for everything and it wouldn’t be just if we said that we did…If we understand the characteristics of complex systems, we can work with those characteristics. If we don’t understand them, we can actually inadvertently block them and go against what we want to achieve.

A Closing Note to the Clinician:

I get it. We went to school to look at a patient as a complicated system. We were taught to find something that is wrong and to fix/change it; the patient will feel better as a result. But we have to know better now. It is time to stop thinking about the patient as a complicated machine some of the time and a complex system – with variables beyond our control – only when it is convenient. It is time to move the profession forward.

Some patient’s pain complaints will improve. Sometimes it will be (in part) due to your intervention, other times it is an illusion (in which case, get over yourself, they were going to get better anyway). And here is another newsflash: even when the patient does get better, it is unlikely to be for the reason why you think they did.

How is it that when it is the patient’s fault, we blame a complex system beyond our control (they won’t stop smoking, they are non-compliant, they have ‘psycho-social issues’). How is it that at the same time we place accountability on complexity in those situations where we fail, we take take credit for the output of the same system when we think we succeed? It is sheer hubris.

If you want to continue to seek the one complicated approach that is better than all the others, I won’t discourage you from doing so. If, while using your favorite approach, you see a bad posture, fascial restrictions. an AIC, a less-than-optimal thoracic ring or a crossed pelvis, you are free to use whatever approach you see fit to try to provide your patient with novel stimuli to alter a neurotag. You are working with a complex system, after all, and you very well may have a profoundly positive impact on that patient – I hope that you do.

But, in the event that you are successful, keep your clinical reasoning to yourself, unless you also want to include in your humble explanation to the patient all of the non-specific and complex variables that also intervened, uncertainty and doubt included. Do not send them home thinking that you fixed something that was necessarily wrong, and THAT is why they feel better. Don’t you dare. You know better. You know that working with a complex system necessarily prevents that from being the case. You know that you have a responsibility to provide that patient’s nervous system with a scientifically valid and appropriate initial condition to live the rest of their life with, one with a defensible understanding of why they feel as good as they do.

In the end, we are residential electricians. Don’t overcharge the customer while telling them that you are responsible for the power grid.

*all quoted materials are from the Complexity podcast

**I need to attribute this metaphor to Diane Jacobs, PT. I thought I had come up with it by myself, but after some research, I discovered I had read something similar last year. I felt as if I had slept on Ziggy bedsheets (Seinfeld reference)


5 thoughts on “In Pursuit of Understanding

  1. Nice one, Keith. Not exactly ‘short and precise’ but I really did enjoy reading it. You make some very important points. Just out of curiosity – how does it go down with clinicians in your part of the World?
    Morten (

    • Thanks for the reply, Morton; my apologies for not responding more promptly.

      So far, the series of posts on complexity was incredibly well-received, but hasn’t seemed to bring about the dissonance that I was hoping for. For example, I have been followed, liked or retweeted by individuals whose own web-sites/blogs speak to (as examples that readily come to mind) how pronation leads to back pain and how proper posture is important to reduce the likelihood of a painful disc herniation.

      So how has it gone down? I don’t think it has sunk in yet.

  2. Keith this was a great one going to share it with as many people who will listen.

  3. Keith, this is wonderful!
    Since I read Diane’s interactor vs operator texts, I’ve been on a “conversion journey”. Been trying to get my head around complexity, emergence, and what we actually do (and don’t do) as physical therapists.
    Thanks a lot, good points and well written!

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