There are two ways to get at the essence of how emotional experience differs from one person to another. The first is to look at feelings and the second is to look at people. Let’s start by considering a metaphor that I believe is entirely appropriate: feelings are like water. As with water, feelings seem to have a movement or flow – they ripple up, settle down, seek a release, explode from within. The flow, by definition, is energetic; the very word emotion connotes movement.
Picture this movement as fast or slow, heavy or light, or any degree in between. Ascribe other qualities as well. For example, anger feels sharp. Sadness feels heavy. Joy feels expansive. Fear feels racing. Regret feels tugging…and so on. Now, picture feeling in general as a stream within the body, in continuous motion. Imagine, further, that the very flow animates us (we say of a lively person that “she (or he) seems very animated today”). We now have a way to picture feeling acting very much like water – bubbling up, pooling, meandering, boiling over, receding.
The second way to get a handle on characteristic differences in emotional experience is to look at individuals themselves. We noted earlier that some people are high reactors and some low reactors (corresponding to two distinct types of PTSD). Another means of framing that essential difference is through a concept known as Boundaries. This is a measure of how much ‘gets’ to people, whether in the form of environmental stimuli (sights, sounds, smells, tastes, textures) or emotional stimuli. “Boundaries” conjures up the idea of a divide between inner and outer – but also a borderline internally between what’s conscious and what’s unconscious, what becomes evident to a person and what he or she is unaware of.
As explained by psychiatrist Ernest Hartmann of Tufts University, the concept suggests that everyone falls somewhere along a spectrum from “thick boundary” to “thin boundary.” Thick boundary people seem thick skinned: not so much gets to them. By contrast, thin boundary people seem thin skinned: lots of things get to them. Thick boundary people are stolid; thin boundary people are sensitive. Internally, thick boundary people are less aware of what they’re feeling in general than thin boundary people, who are often very aware. Adjectives that tend to apply to thick boundary people are rigid, calm, deliberate, well organized (they keep everything “in its place”), persevering. Adjectives that tend to apply to thin boundary people are open, vulnerable, reactive, flexible (they see “shades of grey”), agitated. As with most dimensions of personality, most people are somewhere near the middle of the spectrum versus at either extreme.
Now, let’s combine the notion of feelings as water with the concept of thick and thin boundaries. I suggest that the flow of feeling is actually quicker and more direct in thin boundary people and slower and less direct in thick boundary people. Thus, individuals who are on the thin side of the spectrum will be quicker to realize what they are feeling – and express or react to it – than individuals on the thick side of the spectrum, for whom feelings are often “out of sight, out of mind.” However (and this is important), anyone can ignore, repress or dissociate from feelings that are especially intense or threatening.
Through the image of feeling as a flow through the bodymind and through an appreciation of boundary differences from person to person, we can now shed light on the remarkable finding that PTSD comes in at least two forms: a high reactive and a low reactive kind.
As we saw, in the more typical (flashbulb) form of PTSD, the emotional or limbic part of the brain becomes hyperactive because the medial prefrontal structures that normally regulate this activity are damped down. A flashback occurs and the fear that the person first experienced during the traumatic episode recurs in full force. The person’s “felt state” (as registered in the insula) is substantial, informed by all kinds of bodily input. It is as if a wave of feeling is cresting, overwhelming the neural circuitry.
By contrast, in the dissociative form of PTSD, the functioning of the limbic part of the brain is over-regulated so the person feels distant, numb, or nothing at all. His or her felt state is diminished, as a paucity of bodily information registers with the insula. It is as if the flow of feeling has been minimized, diverted or dammed up. This state of things is episodic with PTSD but is characteristic of alexithymia (the condition we learned about before where a person has no idea – and hence no description of – what he or she is feeling).
My conjecture is that the majority of people who suffer from PTSD are thin boundary. These are people who feel things keenly, who respond strongly to physical and emotional pain in themselves as well as in others. These are also people who register sensory stimuli (sights, sounds, smells, etc.) fairly vividly. Furthermore, the images and feelings contained in their memory are close at hand. The boundaries of people like this – the dividing line between them and the external world and the threshold between conscious and unconscious within – are fairly porous.
The 12%-25% of PTSD patients that exhibit the dissociative form of the condition are another story. These are people who are not terribly conversant with their own feelings or, consequently, other peoples’ feelings. They’re less apt to be affected by sensory stimuli. And memories typically stay in the past; they’re not readily brought to mind or ruminated upon. The boundaries of people like this – both between them and the external world and delineating between conscious and unconscious within – are relatively impermeable.
A good deal of evidence, both anecdotal and scientific, supports this assessment of PTSD. On the anecdotal side, consider the following statement made by a combat veteran. The smell of gunpowder, he said, not only makes him feel hot, “It’s as if my whole metabolism changes.” This is clearly a thin boundary person. What he experiences is intense as well as instantaneous. Additional biological evidence that most PTSD sufferers are high reactors is contained in my book, Your Emotional Type. People with alexithymia, on the other hand, have been shown to be strongly thick boundary, suggesting the same is true for those who exhibit the dissociative form of PTSD.
It should be added that, even within this framework, the lines are not always clear-cut. Some people who dissociate are constitutionally thin boundary. Like the proverbial turtle, they may go into a shell to protect themselves from violence or emotional tumult (especially if these threats are encountered at an early age). It’s been found, for example, that some people with dissociative symptoms also startle in quite a pronounced way upon hearing a loud noise. This reflex suggests that not only are they constitutionally thin boundary but that their superficial overreaction corresponds to the extent their emotional reactivity has gone ‘underground.’