Do we ever really know reality? Or do we only experience the world thru our own perception of reality? Modern neuroscience indicates quite clearly (read Subliminal) that our subconscious interpretation of sensory input is largely viewed thru a predictive lens informed by our past behaviors and experiences. Our sensory perceptions are a representation of reality - a map of brain activity - and the associated behavioral outputs give these maps meaning. Our perceptions are ever-changing, molded by the environment and our interaction with it. In some instances, perceptual maps can become distorted and their view of reality can be overcome by pain, fatigue, or anxiety. In this post I want to look a little closer at how stressors influence our perceptions of reality.
"Every act in every moment is the emergent product of context and history" Esther Thelen
Predictions and "Negative" Outputs
Our perceptual maps of the world are critical for efficient processing, allowing our brains to quickly categorize sensory information. The brain scrutinizes this information, using context and history, to come up with an output. This output constitutes a behavior - whether it be muscular tension or contraction, pain, postural adjustment - to interact with the current sensory environment. It's our brain's best guess based on what we already know has worked in the past.
Imagine walking down a dark alley, there's a flickering street lamp, several sketchy-looking strangers and maybe a rat even scurries across your path (this is straight-up stereotype). Think you'll be a bit on edge and hyper-vigilant even if you've never actually had anything bad happen to you in an alley? This is pretty easy to imagine because somewhere along the line you developed a perceptual map of dark, sketchy alleys.
But were you born with this map? Do babies know not to waddle down dark alleys? Probably not, rather it was developed from the environment - seeing bad things happen to Bruce Wayne's parents on TV, your parents hurrying you by the alley when you were young, or maybe you were even attacked in one. You developed a representation of what a dark alley is thru context (day vs. nite) and history, with an emotional valence. As stressors accumulate, that dark alley starts to expand and encompasses more and more of our reality, so that even the anticipation of a flickering street lamp outside your house sends you into fight/flight mode with all the muscle tension, nociceptive sensitivity, and altered breathing that comes with it. Eventually, even imagining the alley sets off a physiological response. Our internal representations, our maps, dictate expectations and our resulting behavior in what appears to be a self-fulfilling prophecy.
Maps and Stress
When stressors reach a critical mass (aka allostatic load), whether acute (injury, just got canned from your job, emotional trauma) or chronic (loss of sleep, poor diet) we revert to our more basic, idiosyncratic tendencies. And I think this largely stems from our maps. At some point along the stress/arousal curve we simply don't have a representational map that includes such stressors so we categorize them with a negative bias predicated on survival. In essence, we become increasingly hyper-vigilant to inputs and our perceptual maps change to reflect this vigilance. From our own perspective threats become louder, larger, and grab more of our attention - we can't see beyond the map because we are in it as in the story of the blind men and the elephant.
When under duress, our maps and thus our perceptions become more rigid and hyper-focused without as many options. We can't see the forest because we are in the forest. And because the nervous system is constantly scrutinizing inputs against its expectations, it begins categorizing them based on increasingly limited predictive models of reality. That is to say, when stress exceeds perceived tolerance more and more inputs are classified as negative and threatening. The maps and their masters become a one-trick pony likely due to disinhibition. [Here's a fascinating piece on stress and the predictive brain in the New York Times.] It's important to remember that this is a dynamic, emergent process in that our maps are constantly altered to reflect our past and current selves. This is likely why so many in persistent pain have learned to identify and embody their current status as if they can't see past the pain it becomes an entity.
The inherent neuroplasticity of our maps enable this process to rapidly change to meet the demands of the environment. This is a good thing as it evolved as a method of survival - it's pretty important to pay attention to something that could endanger you. The problem becomes when the maps continue to expand with lesser and lesser perceived threats. This is likely a contributing factor in the widespread problems of chronic pain, fatigue, anxiety, and probably any other negative output you can think of.
So what constitutes a healthy variable map of reality and how can we help train this in ourselves and others? More on that next time...
P.S. This is my current opinion on the matter based on the most recent evidence. I fully expect to modify this take as I learn more. Probably after reading this book.