Pain: It’s not just personal

Pain can be paradoxical: On the one hand we know that pain is by definition a fundamentally subjective and individual experience. As psychologists we have fought long and hard to change the public and scientific understanding of pain as a purely medical phenomenon towards a biopsychosocial construct. On the other hand we know that pain is not suffered alone. Pain is constantly interpreted by and communicated to others around us, making it an interpersonal experience as well. Our challenge as pain researchers is to reconcile this paradox and understand the complex dynamics of biological, psychological and social aspects of pain.

While the majority of research often approaches pain with regard to the individual, the interest in interpersonal dynamics of pain perception and communication is growing. To name just two examples, take the popular (and controversial) idea of “social pain” (the finding that physical pain and social exclusion share common circuits in the human brain [1]) or Tine Vervoort’s research on parent-child interactions in the context of pain (see her BiM post). However, there are still gaps in our understanding of interpersonal dynamics in pain.

In our own lab, we have tried to pinpoint the role of pain-related fear in the development and maintenance of chronic pain complaints. We know that the fear of pain is important—at times more important than pain itself [2, 3]. We also know that fear of pain can be learned and extinguished in the lab (see here and here for Ann Meulders’ related Star Wars stories). Yet, we are almost clueless when it comes to the question of if and how social context can actually affect pain-related fear. Consequently, in the very first study of my PhD project we tried to shed light on exactly this question.

We adapted the voluntary joystick movement paradigm that was developed in our lab to study the acquisition and extinction of pain-related fear to study the effects of social context [4]. We asked 42 healthy participants to come to the lab and perform the following task: Participants were seated in front of a computer screen and used a joystick to perform movements (either to the left or the right as prompted by the task). Unfortunately for the participants, one movement direction was followed by an electric shock while the other one was not. As in previous studies, we expected participants to learn after several repetitions that one movement direction is safe and the other is painful. Hence, we expected that participants would start to exhibit fear during the painful movements but not during the “safe” movements. So far so good.

Here comes the catch: In contrast to earlier studies, we added pictures of angry or happy faces to the background of the task. These pictures did not predict the occurrence of the shocks; they were simply ’staring’ at the participant while they performed the joystick task. Half the participants were stared at by angry faces, while the other half saw happy faces. In this way we tried to create a threatening and a safe social context during the task. We wanted to know whether participants would learn differently depending on which faces were present in the background. We asked participants prior to each movement how fearful they were to perform it and how much they expected it to be followed by a shock. Moreover, we also measured their startle reflex as a psychophysiological indicator of fear in addition to self-report.

So, did social context matter? It did. As expected, all participants learned that one movement direction was painful and the other one was not, but participants who saw the angry face learned it better. As in previous studies, we found that participants reported more fear and showed a stronger startle reflex during painful movements compared to safe movements, but this difference was bigger in the group that was confronted with a threatening social context. In other words, participants in the threatening context were better able to distinguish between painful and non-painful movements than participants in the safe context. Interestingly, even though there were differences in fear learning, we did not find any difference between the groups with regard to perceived painfulness of the shocks.

What can we conclude? Social context matters. It can affect our learning processes, and does so also in the context of pain. While we can only speculate about the underlying mechanisms at this point, it seems plausible that a threatening environment (be it social or not) could facilitate the rapid distinction between threat and safety [5]. From an evolutionary standpoint this distinction could have immediate consequences for survival, especially in a threatening situation.

As so often in research, this study warrants and raises numerous questions. Would we find similar effects with an actual social interaction rather than pictorial facial stimuli? While the facilitation of pain-related fear learning might be adaptive in our experiment, could it also become maladaptive (one might think of prolonged experiences of social threat such as bullying)? How does the situation change outside the lab, for instance with regard to patients suffering from chronic pain?

For now, these questions will remain unanswered. But as you might have guessed: to be continued.

If you would like to read the full story, please check out the recently published article here.[6]

About Kai Karos

Kai KarosKai Karos finished his bachelor and research master degree at Maastricht University, the Netherlands. He is currently a doctoral researcher in the Research Group on Health Psychology at the University of Leuven (Belgium) under the supervision of Johan Vlaeyen, Ann Meulders and Liesbet Goubert. His PhD research concerns the effects of a threatening social context on pain perception and pain expression. These processes are mainly investigated using experimental laboratory research with healthy participants.  For more information see here.

References

[1] Eisenberger NI (2015). Social pain and the brain: controversies, questions, and where to go from here. Annual review of psychology, 66, 601-29 PMID: 25251482

[2] Crombez G, Vlaeyen JW, Heuts PH, & Lysens R (1999). Pain-related fear is more disabling than pain itself: evidence on the role of pain-related fear in chronic back pain disability. Pain, 80 (1-2), 329-39 PMID: 10204746

[3] Vlaeyen JW, & Linton SJ (2012). Fear-avoidance model of chronic musculoskeletal pain: 12 years on. Pain, 153 (6), 1144-7 PMID: 22321917

[4] Meulders A, Vansteenwegen D, & Vlaeyen JW (2011). The acquisition of fear of movement-related pain and associative learning: a novel pain-relevant human fear conditioning paradigm. Pain, 152 (11), 2460-9 PMID: 21723664

[5] Öhman A, & Mineka S (2001). Fears, phobias, and preparedness: toward an evolved module of fear and fear learning. Psychological review, 108 (3), 483-522 PMID: 11488376

[6] Karos K, Meulders A, & Vlaeyen JW (2014). Threatening Social Context Facilitates Pain-Related Fear Learning. J Pain PMID: 25510542