Experience is Reality: Lessons from Trauma

 

The simulation hypothesis is popular these days in certain high-tech-influencer circles. It's the idea that we are all currently living in a world like the one envisioned in the Matrix movies, where everything we see and do is produced by a computer program. If you haven't heard this one before, start with philosopher Nick Bostrom's 2003 paper "Are You Living in a Computer Simulation?", which presents a mathematical-odds-based argument. Some versions of the argument suggest that the more unlikely the events that have occurred -- for instance, the possibility that Donald Trump would win the White House not just once, but for two non-consecutive terms -- the less likely it is that the world we live in is the actual "base level" world rather than an interesting simulation experiment. For a fuller contemporary treatment of these ideas, I recommend David Chalmers's 2022 book Reality+. In a recent post, I also tackled the question of whether it makes sense to formulate rational arguments if we do not have an accurate perception of our own underlying reality.

All forms of the simulation argument crucially rely on the idea that what we experience about the world is not necessarily the way the world actually exists. You might be familiar with this idea from Rene Descartes, who coined the argument "I think, therefore I am" (cogito, ergo sum) in response to a thought experiment in which a malevolent demon was actually deceiving him about everything he saw, did, and believed; the one thing that he couldn't bring himself to doubt was the fact of his own existence as a conscious being. A more modern version of the same thought experiment is the brain-in-a-vat scenario: Like Neo in the Matrix, perhaps everything we experience is being produced by a computer input into our brains, and not by any genuine interaction with the world around us.

Is this really plausible, though? All claims for simulation rely on the idea that we could be fooled in some fundamental way about reality, that our experiences can be out of sync with what's happening. We certainly all have small examples of being wrong in our expectations or beliefs, but is that really the same as having a total experience that is visceral, compelling, and also wrong? Descartes suggested that dreams met this criteria; I but have argued elsewhere (following the work of Eric Schwitzgebel) that we actually don't experience dreams in the same way that we experience other parts of life. Lucid dreams are the exception that proves the rule that dreams are different. And other philosophers, such as G.E. Moore, argue that reality is just too real to doubt. His refutation of Cartesian skepticism was to look at his own hands and declare "here is one hand. Here is another. Therefore, the external world exists!"

As a psychologist, however, I can suggest one example in which people experience a different reality from what's actually surrounding them, and believe it to be fully real. That example is trauma. In The Body Keeps the Score, Bessel van der Kolk describes various scenarios in which traumatic experiences result in unusual experiences and behaviors, which feel very real to the person involved but don't match that person's immediate reality. Some of the sensations common to post-traumatic stress disorder (PTSD) include a racing heartbeat or inability to calm down, strong fight-or-flight reactions to unthreatening everyday situations, and re-experiencing sensations from the trauma in the form of unwanted thoughts or feelings, disturbing dreams, or "flashback" experiences in which one re-lives the events. Although flashbacks are the most vivid example of living through experiences that are different from reality, these PTSD symptoms exist on a continuum and any of them to some degree seem to fit the bill -- a vivid, multi-sensory experience that is not reality-based. Because PTSD symptoms are so distressing, many people with these experiences go on to develop unhealthy habits, chronic health problems, and substance use problems as a form of self-medication (as seen in our 2023 study with Colorado back country search and rescue workers who had traumatic stress).

Traumatic memories may have such power because they are stored differently in the brain than other memories. One theory is that the brain's "indexing" function is missing an entry for the traumatic memories -- the book is there on the shelf, but the card catalog card has been removed from its drawer. Traumatic memories show less functional connection, which is a measure of whether different parts of the brain are similarly active at the same time. In normal memories, memory areas light up at the same time as areas connected to a person's sense of self and normal understanding of the world. But traumatic memories seem to exist as "fragments," cut off from other memories and experiences. These memories seem to activate emotional parts of the brain (in the Intuitive system) without simultaneously activating the Narrative portions of the brain that allow us to tell coherent stories about our lives. The unusual memory storage characteristics of traumatic memories may account for their ongoing emotional power, such that people experience these memories with all of their sensory and physical vividness despite now being in a completely different context. 

I have had just one personal experience with this type of disconnected reality (at least, one that I know of!). I was in a bad automobile accident in 2016, resulting in some neurological impairment. I felt some level of anxiety when I started driving again, but I wasn't having other strong indications of PTSD. Nevertheless, I had a single flashback, which happened when I was talking about the accident in the context of some neurological testing. I was describing what had happened, when suddenly I was no longer sitting in a chair in a psychologist's office. Instead, I was in the driver's seat of my car, looking through the windshield at another car about to collide with me head-on. It only lasted for a few seconds, but it was indistinguishable from ordinary reality. 

The seeming reality that occurs when people re-experience traumatic memories, which has its own neural signature in the brain, suggests that we can in fact have untrue experiences that subjectively feel the same as reality. Whether technology will ever reach the level of creating such realistic simulations (or, in the view of people who believe the simulation hypothesis, already has), it appears that the key to making simulations believable will be found at the level of the Intuitive Mind.