perception

Why learning about pain can help – an old study worth revisiting


If you’ve read my blog over the years you’ll see that I love a bit of history. Learning from older studies, and older opinions, can help us position our current thoughts in a larger context. Older studies can also highlight concepts that haven’t grabbed the attention nearly as much as more recent studies but still have value.

Today’s post is about a studied published in 2004. It’s one I’ve often used to illustrate how influential our expectations or beliefs are when it comes to pain intensity and pain aversiveness/unpleasantness.

Take 31 healthy undergraduate students (50% were women in this case). Split them into two groups, and offer them a small incentive (a large bar of chocolate and a soft drink – OK I’m in!). Hold a set of objects to the back of their necks and ask them to rate the experience on a set of visual analogue scales ((1) very soft–very hard; (2) not prickling–very prickling; (3) not noticeable–very noticeable; (4) not painful–very painful; (5) not rough– very rough; (6) not damaging–very damaging; (7) not pleasant–very pleasant; (8) very cold–very hot; (9) very simple–very complex.). The objects were:

a feather, a small mirror, a rough brush, a paper handkerchief, a metal bar, a piece of hard plastic, a piece of sand paper, and a gel. The metal bar (aluminium, length 17.5 cm, diameter 3 cm) was cooled down to -25 degrees Celcius. This temperature was chosen because it’s not damaging when held briefly against the skin.

Each person was then individually exposed to the item, and asked to complete the ratings. The only difference between the groups was that participants were told just before the metal bar was applied, “this is very hot” or “this is very cold”.

The findings supported the hypothesis: when people thought the stimulus was hot they rated it as more painful AND more damaging than when they thought it was cold.

What do we make of this? The simple interpretation is that people interpret what happens to them in light of what they think is going on. That meaning influences the experience of pain. And that this interpretation occurs rapidly and without conscious awareness. The authors argued that attentional focus, anxiety and interpretation all influence the experience – however, in this instance, attention to the stimulus was greater in the case of the “cold” stimulus than the hot. Anxiety might influence attention to a stimulus, and “hot” might be more anxiety-provoking than “cold”, enhancing attentional awareness – or not. So the final consideration from this study is that if interpretation is essential in perceptual processing, tissue-damage related meaning might itself influence how pain is perceived.

The authors conclude by saying that their findings “support the hypothesis that higher order psychological processes influence the experience of pain” and go on to say they are “also of clinical importance, as they suggest that correction of dysfunctional interpretations of pain might help to reduce the burden the experience of pain poses on many people.”

Since this paper was published we have seen a proliferation of educational approaches to help people experiencing pain interpret this in a different way. I’m loathe to describe a person’s interpretation as “dysfunctional” because it is their experience – and at the same time I’m also aware that many unhelpful terms are used to describe what might be going on inside a person’s body. Some examples include “wear and tear” for osteoarthritis, “an unstable pelvis”, “your back has gone out”, “your spine is out of alignment” – the list goes on.

Here’s the thing: we can absolutely acknowledge a person’s distress at what they understand is going on, and what it feels like to them. We should, I think, always be compassionate and validate the distress we see in a person. That is real and their experience.

Here’s another thing: when the distress is based on inaccurate or unhelpful information, then I think it’s unethical to leave a person thinking this – even if we’ve offered validation and compassion. Would we leave a person to believe they had cancer when they didn’t? And yet some people would argue that to offer an alternative explanation somehow invalidates the person’s experience. We can both validate the distress a person is feeling AND offer a more workable or useful alternative.

At this point in my blog I want to be absolutely crystal clear – I do not know all the mechanisms involved in pain. Nobody does. And none of our explanations are terribly “True” with a capital T, because we actually don’t know. We do have some workable explanations to dispute or replace some unhelpful or unworkable explanations – eg that what we can see on imaging doesn’t equate with pain; that “issues in the tissues” are poorly correlated to pain; that “wear and tear” is often interpreted by people as “I’m wearing out” when it might be more useful to describe osteoarthritic changes as “age-related changes”. We definitely know that the brain is involved in our pain experience, and we know that various so-called psychological processes influence how much of a nociceptive stimulus is processed. What we don’t know is how – and that’s OK. To a great extent the “how is pain ‘produced'” question remains unanswered. But to leave people with an impression that “if I bend without using my core, I’ll do serious damage”, or “this could leave me in a wheelchair if I’m not very careful” in the name of validating a person’s experience is, I think, the very worst example of paternalism.

Do I espouse any particular way of helping someone make sense of their experience? Yes, glad you asked. My preference is to take the person through their own experiences, to help them “join the dots” of the various factors that might be influencing their pain. If, and when, it’s appropriate I might add in some things we know about pain such as increased anxiety likely increases pain and attention to pain – and this is why, in the middle of the night when there’s not much going on, and a person isn’t sleeping, they might notice their pain really going nuts. I accept that pain is present, and how or why isn’t nearly as important as exploring what this person notices about their own pain. And sometimes that might include some gate control theory, some neuromatrix, some descending inhibition information, and so on. In the service of my clinical reasoning about why this person is presenting in this way at this time, and what might be maintaining this person’s predicament.

TL:DR – what a person thinks is going on has a powerful influence on both pain intensity and unpleasantness (oh and beliefs about harm). This matters because some explanations given to people (and some of the rubbish found on the internet) are not helpful at all.

Arntz, A., & Claassens, L. (2004). The meaning of pain influences its experienced intensity. Pain, 109(1-2), 20-25. doi:10.1016/j.pain.2003.12.030

Can you inflict pain without flinching?


Just for something a little different today: I nipped on over to YouTube and searched for ‘pain’ – what did I come across? Well, apart from h e a p s of really stupid ‘Jackass’ type of home video inflicting pain on each other and laughing maniacally… there were a couple of really interesting psychology clips that caught my eye.

This one made me think, particularly after considering the difficulty some therapists have in ‘pushing’ patients to do activities despite pain…(see my post from a couple of days ago ).

Jean Decety, Professor, Psychology and Psychiatry, explains his research into pain responses and how physicians learn to turn off the part of the brain that activates feelings of empathy. Decety co-authored “Expertise Modulates the Perception of Pain in Others,” published in October 2007, which discusses the necessary ability of a doctor to regulate pain perception in order to better treat patients.

It’s a quick video – so take a moment to enjoy!