Thinking Fast and Slow is the seminal work of psychologist and Nobel Prize winner in economics, Daniel Kahneman, It has become an essential resource in professions where understanding behavior is an instrumental part of what they do. This, of course, also applies to physical therapists. As I was reading the book, I couldn’t help drawing connections from many of the concepts that Kahneman writes about to the perception of pain. It seemed to help make further sense of the difficult processes involved in the pain experience, especially if we consider the Mature Organism Model (MOM) of pain perception, originally proposed by Louis Gifford.
It is my intent in this post to deconstruct Kahneman’s work as how I see it fitting in to our current understanding of neuroscience and pain perception. For the sake of simplicity and length, I have divided it up into three parts. Part I will be an introduction to the concept of the two systems that guide our decision making. Part II will discuss the concept of associative coherence, and part III will highlight priming and the ideomotor effect.
Kahneman begins with a discussion of the two systems, simply referred to as “System 1” and “System 2.” It is the interplay between these systems that governs our decision making. System 1 is our intuitive fast thinking. System 2 is slower and more deliberate. We like to think of ourselves by our System 2 — our conscious, reasoning self, however, as Kahneman points out, System 1 is the real driver of most of our thoughts and feelings. The interesting thing is that System 2 often works off the unconscious intuitions of System 1. But with practice and repetition, System 1 can be affected by the deliberate, focused work of System 2, and develop it into automatic, intuitive responses. This is a positive thing when it comes to things like playing a musical instrument or developing manual therapy skills. Yet, it is not so advantageous for individuals prone to developing chronic pain. However, it makes for the ability to “unlearn” patterns and develop new ones, the hallmark of neuroplasticity.
“System 1 includes innate skills that we share with other animals. We are born prepared to perceive the world around us, recognize objects, orient attention, avoid losses, and fear spiders. Other mental activities become fast and automatic through prolonged practice”
Some examples of System 1 functioning are recognizing facial expressions, determining that one object is farther away than another, and adding 2+2. If we’re asked to multiply 17×24, you’re now recruiting System 2. Multiplying 17×24 requires much more effort (and pencil and paper or calculator app for me). System 2 requires attention and cannot keep attention if disrupted. For example, you can drive to work on an open road while listening to your favorite PT podcast and be able to focus on and retain what you’re listening to. That’s System 1–it can handle multiple things at one time as long as they are easy and relatively effortless. But if you encounter heavy traffic or bad weather, you may realize later that you hardly recall anything you were listening to because you had to tune in more to the environment as well as your driving. That’s System 2 working and it can’t function well with distraction. Ultimately, the control of attention is shared by the two systems.
“System 1 runs automatically in the background and System 2 is normally in a comfortable low-effort mode, in which only a fraction of its capacity is engaged. System 1 continuously generates suggestions for System 2: impressions, intuitions, intentions, and feelings. If endorsed by System 2, impressions and intuitions turn into beliefs, and impulses turn into voluntary actions”
System 2 requires effort. Think about how you have felt after a weekend CE course where you’re learning new information, new ways of thinking, and perhaps new intervention skills throughout the whole day. You were likely operating in System 2. Everything took more focus, effort, and energy. With practice and experience we become more efficient with a complex task like performing an upper cervical HVLAT manipulation, for example, but those same processes may include how we interpret “threatening” stimuli. In patients with persistent pain, this process may be over-active.
“System 2 is activated when an event is detected that violates the model of the world that System 1 maintains. Surprise then activates and orients your attention: you will stare, and you will search your memory for a story that makes sense of the surprising event”
Consider the example of touching a hot stove. You withdraw your hand before the stimulus even reaches conscious awareness. You can later rationalize that the discomfort you might feel and the fact that you withdrew your hand so quickly is a result of accidentally touching a surface that was still hot. This is due to the sophisticated process System 1 and 2 undertake to determine how to share attention. Evolutionary-wise, System 1 is in charge when responding to the quickest and most dangerous threats. This is not a time to stop to think and reason.
Consider a patient with chronic LBP–a movement to pick up something off the floor may trigger a response that is interpreted as pain. The intuitive response from System 1 is that some sort of tissue injury must have occurred. In the case of chronic pain, we know that is not likely to be the case. The pain response is partially pulling from memory of a previous flexion-related injury that resulted n a “bulging disc” later “confirmed” on MRI. They reason that now they must have irritated it or caused more “damage.” Challenging these assumptions takes the work of System 2, which requires cognitive effort. This is a challenge for most people because System 2 likes to be lazy. We would much rather solve 2+2 than 17×24. As Adriaan Louw and Louie Puentedura write in Therapeutic Neuroscience Education, in people with persistent pain, the parts of the brain that are involved in focus and concentration, most notably the anterior cingulate cortex and the thalamus, are already involved in a pain process, so they are less able to perform more complex reasoning tasks. Could this be another reason why “explaining pain” to patients is so challenging?
Understanding how our reasoning systems work may help shed some light as to why certain people respond in certain ways, and why it may be so difficult to help them to understand the nuances of pain neuroscience–it challenges how their brain automatically “makes sense” of the event. And much like our own reasoning, (EIP, anyone) when we believe an event or statement to be true, we very commonly ignore evidence to the contrary and instead, believe arguments that support it, regardless how unsound.
Look at the following image (Kahneman uses it in his book as does Louw and Puentedura in Therapeutic Neuroscience Education)
From experience, you know the horizontal lines are the same length. Measure them and check. I “know” they’re the same length and even while looking at it I still have to convince myself they are because everything I “see” tells me that the one on top is longer. System 1 is what is providing me with that thought. Kahneman writes,
“You cannot decide to see the lines as equal, although you know they are. To resist the illusion, there is only one thing you can do: you must learn to mistrust your impressions.”In this sense, when our patient with chronic low back pain bends forward, they perceive their pain. Their nervous system has associated that movement with their symptoms. As the Hebbian theory states, “neurons that fire together, wire together.” Every time the patient bends forward, (or at least is aware of themselves bending forward), their back hurts. Consider Pavlov’s dog: the bell rings, food is presented, and the dog salivates. After a period of time, just the ringing of the bell is enough to cause the dog to salivate. With persistent pain, the movement circuit becomes linked to the “pain” circuit. Furthermore, patients’ will commonly verbalize that they “know” that if/when they bend forward, they will experience their back pain. The expectation/fear/anxiety circuit can also become linked to the “pain” circuit. The more often they fire, the more efficient they get and the more linked they become. This is one reason why “old habits are hard to break.”
Part of our treatment will be trying to get those individuals to disassociate particular movements with pain. However, as the Muller-Lyer illusion above illustrates, it is definitely an undertaking to convince people that what they “see” or “feel” is not in fact, an accurate representation of reality. The good news is that just like Pavlov’s dog stopped salivating after a period of time of bell ringing without food being presented, we can sometimes help disconnect the wired circuits of anticipation, movement, and pain. And we can possibly use the processes of System 2 (focus, practice, repetition) to help re-influence the automatic intuitions of System 1. Stay tuned for Part II.
As always, thanks for reading. Comments and discussion welcome.
-Andrew - via RealPTTalk.com
Interested in live cases where I apply this approach and integrate it with pain science, manual therapy, repeated motions, IASTM, with emphasis on patient education? Check out Modern Manual Therapy!
Keeping it Eclectic...