- Email: [email protected]
A science of pain expression?
Pain 125 (2006) 202–203 www.elsevier.com/locate/pain
Editorial
A science of pain expression? In this issue of Pain, Sullivan and colleagues provide an innovative and intriguing advance in understanding the complexities of pain expression by demonstrating that different categories of behaviour respond in a dissimilar manner to variations in contextual demands. Pain behaviours that have a primary communicative function (e.g., self-report, facial grimacing, or paralinguistic vocalizations, such as voice qualities or grunting, moaning and sighing) collectively indicate more painful distress when explicit social demands focus on communicating pain as opposed to when the focus is upon a neutral task (providing estimates of physical properties of an event). In contrast, other behaviours (guarding, holding, touching or rubbing) that more immediately control or minimize painful experience are not as variable in response to the different social contexts, but vary more closely with the painful, physical demands of tasks. Hence, the functional importance of specific types of pain expression is highlighted and these properties should command the attention of investigators and clinicians. As well, in directing attention to the functional significance of dissimilar categories of pain behaviours, the findings recognize the reality that pain behaviour is more than an expression of subjective experience but also reflects the complexities of the interaction of individuals with the specifics of the environments in which they find themselves. It is clear that it is inappropriate to consider different types of pain behaviour to be equivalent. As Prkachin (1986) observes, pain behaviour is not unitary. The challenge posed by this paper for scientists and clinicians is to generate and implement a science of pain expression that is likely to be as rich and complex as the current focus upon our understanding of the sources and varieties of the subjective experience of pain. To date, the term pain behaviour has had no accepted definition and is often used very generally to incorporate diverse behaviours classified only by their topology or co-occurrence, with little reference to antecedents, consequences, or presumed or demonstrated function. Sullivan et al. represent this neutrality about function – a neutrality consistent with a strict behaviourist approach to the subject – by defining pain behaviour in the intro-
duction as follows: ‘‘Pain behaviours are the various actions or postural displays that are enacted during the experience of pain’’. Parenthetically, the authors effectively note the erroneous assumption often made that self-report reflects pain experience, but is not a pain behaviour. In fact, both self-report and nonverbal behaviour are forms of pain behaviour and both represent aspects of pain experience, with varying degrees of fidelity, best understood by appreciating the separate adaptive functions each serves. Sullivan et al. (2006) are right in observing that surprisingly little is known about the rules governing expression of pain behaviour. A strictly behaviourist or operant formulation argues that pain is expressed contingently, that is, it is regulated by its reward value. This was demonstrated by Jolliffe and Nicholas (2004) who found contingent relationships between verbal pain ratings and social reinforcement in an experimental pain task. Partial support is also evident in sequential behavioural analyses in more naturalistic tasks undertaken by pain patients and spouses provided by Romano et al. (1992). But the latter study produced as many findings not predicted or counter to expectations as those supporting the operant predictions. Clearly more is happening than can be explained solely by reinforcement history. An evolutionary perspective provides this broader understanding – adaptive behaviours promote species survival in the long run. All behaviour, whether characterized as protective or communicative, fulfills this function. In this sense, biology serves behaviour and distinguishing pain behaviours by function will enable us to understand them better, as well as assisting in understanding the biological mechanisms associated with different forms of pain experience and behaviour. The evolutionary perspective (Williams, 2002) also places pain behaviour in a communicative context. In human societies, communication subserves mutual – but conditional – helping, in turn underpinned by social reasoning. This perspective attempts to address questions such as why we should show pain at all, and what mediates understanding and responses to pain display. For the person in pain, the immediate functions of
0304-3959/$32.00 Ó 2006 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.pain.2006.08.004
Editorial / Pain 125 (2006) 202–203
pain are to prioritise escape from the cause of pain or mitigation of the damage, to command attention, to promote vigilance to and avoidance of associated cues, and, in the longer term, to encourage energy conservation and defence during recovery and healing. Interestingly, none of these require that the intensity of pain represents the extent of tissue damage, only that it is sufficiently aversive and attention-grabbing that it motivates personal or social behaviour which maximizes physical integrity. Beyond these intrapersonal functions, pain also enhances interpersonal adaptation by warning others of physical threat, eliciting empathy and altruistic responses and influencing the individual’s role in social hierarchies. The social communication model of pain (e.g., Craig et al., 2002) incorporates not only experience and expression as intrapersonal features of pain, but addresses interpersonal demands upon caregivers and other observers who must assess or attribute pain to the suffering person and possibly deliver care to the suffering person. This model includes consideration of developmental processes, for example, the transformations in pain expression associated with maturation, personal experiences with pain, and the impact of socialization on the utilization of pain language and effective pain expression, if opportunities to enlist care from others are to be optimized (Stanford et al., 2005; Craig et al., 2006). Sullivan and colleagues intend their research and the paradigm from which it arises to stimulate more theoretical and conceptual development, as well as replication and extension of their study. We trust that their paper will have this impact.
203
References Craig KD, Korol CT, Pillai RR. Challenges of judging pain in vulnerable infants. Clin Perinatol 2002;29:445–58. Craig KD, Stanford EA, Fairbairn NS, Chambers CT. Emergent pain language communication competence in infants and children. Enfance 2006;1:52–71. Jolliffe C, Nicholas M. Verbally reinforcing pain reports: an experimental test of the operant model of chronic pain. Pain 2004;107:167–75. Prkachin KM. Pain behavior is not unitary. Behav Brain Sci 1986;186:754–5. Romano JM, Turner JA, Friedman LS, Bulcroft RA, Jensen MP, Hops H, et al. Sequential analysis of chronic pain behaviors and spouse responses. J Consult Clin Psychol 1992;60:772–82. Sullivan MJL, Thibault P, Savard A, Catchlove R, Kozey J, Stanish WD. The influence of communication goals and physical demands on different dimensions of pain behavior. Pain 2006;125:270–7. Stanford EA, Chambers CT, Craig KD. A normative analysis of the development of pain-related vocabulary in children. Pain 2005;114:278–84. Williams AC de C. Facial expression of pain: an evolutionary account. Behav Brain Sci 2002;25:439–88.
Amanda C. de C Williams * University College London, Sub-Department of Clinical Health Psychology, Gower St., London WC1E 6BT, UK E-mail address: [email protected] Kenneth D. Craig University of British Columbia, Department of Psychology, 2136 West Mall, Vancouver, BC, Canada V6T 1Z4 E-mail address: [email protected]
*
Corresponding author. Tel.: +44 20 7679 1608.
Editorial
A science of pain expression? In this issue of Pain, Sullivan and colleagues provide an innovative and intriguing advance in understanding the complexities of pain expression by demonstrating that different categories of behaviour respond in a dissimilar manner to variations in contextual demands. Pain behaviours that have a primary communicative function (e.g., self-report, facial grimacing, or paralinguistic vocalizations, such as voice qualities or grunting, moaning and sighing) collectively indicate more painful distress when explicit social demands focus on communicating pain as opposed to when the focus is upon a neutral task (providing estimates of physical properties of an event). In contrast, other behaviours (guarding, holding, touching or rubbing) that more immediately control or minimize painful experience are not as variable in response to the different social contexts, but vary more closely with the painful, physical demands of tasks. Hence, the functional importance of specific types of pain expression is highlighted and these properties should command the attention of investigators and clinicians. As well, in directing attention to the functional significance of dissimilar categories of pain behaviours, the findings recognize the reality that pain behaviour is more than an expression of subjective experience but also reflects the complexities of the interaction of individuals with the specifics of the environments in which they find themselves. It is clear that it is inappropriate to consider different types of pain behaviour to be equivalent. As Prkachin (1986) observes, pain behaviour is not unitary. The challenge posed by this paper for scientists and clinicians is to generate and implement a science of pain expression that is likely to be as rich and complex as the current focus upon our understanding of the sources and varieties of the subjective experience of pain. To date, the term pain behaviour has had no accepted definition and is often used very generally to incorporate diverse behaviours classified only by their topology or co-occurrence, with little reference to antecedents, consequences, or presumed or demonstrated function. Sullivan et al. represent this neutrality about function – a neutrality consistent with a strict behaviourist approach to the subject – by defining pain behaviour in the intro-
duction as follows: ‘‘Pain behaviours are the various actions or postural displays that are enacted during the experience of pain’’. Parenthetically, the authors effectively note the erroneous assumption often made that self-report reflects pain experience, but is not a pain behaviour. In fact, both self-report and nonverbal behaviour are forms of pain behaviour and both represent aspects of pain experience, with varying degrees of fidelity, best understood by appreciating the separate adaptive functions each serves. Sullivan et al. (2006) are right in observing that surprisingly little is known about the rules governing expression of pain behaviour. A strictly behaviourist or operant formulation argues that pain is expressed contingently, that is, it is regulated by its reward value. This was demonstrated by Jolliffe and Nicholas (2004) who found contingent relationships between verbal pain ratings and social reinforcement in an experimental pain task. Partial support is also evident in sequential behavioural analyses in more naturalistic tasks undertaken by pain patients and spouses provided by Romano et al. (1992). But the latter study produced as many findings not predicted or counter to expectations as those supporting the operant predictions. Clearly more is happening than can be explained solely by reinforcement history. An evolutionary perspective provides this broader understanding – adaptive behaviours promote species survival in the long run. All behaviour, whether characterized as protective or communicative, fulfills this function. In this sense, biology serves behaviour and distinguishing pain behaviours by function will enable us to understand them better, as well as assisting in understanding the biological mechanisms associated with different forms of pain experience and behaviour. The evolutionary perspective (Williams, 2002) also places pain behaviour in a communicative context. In human societies, communication subserves mutual – but conditional – helping, in turn underpinned by social reasoning. This perspective attempts to address questions such as why we should show pain at all, and what mediates understanding and responses to pain display. For the person in pain, the immediate functions of
0304-3959/$32.00 Ó 2006 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.pain.2006.08.004
Editorial / Pain 125 (2006) 202–203
pain are to prioritise escape from the cause of pain or mitigation of the damage, to command attention, to promote vigilance to and avoidance of associated cues, and, in the longer term, to encourage energy conservation and defence during recovery and healing. Interestingly, none of these require that the intensity of pain represents the extent of tissue damage, only that it is sufficiently aversive and attention-grabbing that it motivates personal or social behaviour which maximizes physical integrity. Beyond these intrapersonal functions, pain also enhances interpersonal adaptation by warning others of physical threat, eliciting empathy and altruistic responses and influencing the individual’s role in social hierarchies. The social communication model of pain (e.g., Craig et al., 2002) incorporates not only experience and expression as intrapersonal features of pain, but addresses interpersonal demands upon caregivers and other observers who must assess or attribute pain to the suffering person and possibly deliver care to the suffering person. This model includes consideration of developmental processes, for example, the transformations in pain expression associated with maturation, personal experiences with pain, and the impact of socialization on the utilization of pain language and effective pain expression, if opportunities to enlist care from others are to be optimized (Stanford et al., 2005; Craig et al., 2006). Sullivan and colleagues intend their research and the paradigm from which it arises to stimulate more theoretical and conceptual development, as well as replication and extension of their study. We trust that their paper will have this impact.
203
References Craig KD, Korol CT, Pillai RR. Challenges of judging pain in vulnerable infants. Clin Perinatol 2002;29:445–58. Craig KD, Stanford EA, Fairbairn NS, Chambers CT. Emergent pain language communication competence in infants and children. Enfance 2006;1:52–71. Jolliffe C, Nicholas M. Verbally reinforcing pain reports: an experimental test of the operant model of chronic pain. Pain 2004;107:167–75. Prkachin KM. Pain behavior is not unitary. Behav Brain Sci 1986;186:754–5. Romano JM, Turner JA, Friedman LS, Bulcroft RA, Jensen MP, Hops H, et al. Sequential analysis of chronic pain behaviors and spouse responses. J Consult Clin Psychol 1992;60:772–82. Sullivan MJL, Thibault P, Savard A, Catchlove R, Kozey J, Stanish WD. The influence of communication goals and physical demands on different dimensions of pain behavior. Pain 2006;125:270–7. Stanford EA, Chambers CT, Craig KD. A normative analysis of the development of pain-related vocabulary in children. Pain 2005;114:278–84. Williams AC de C. Facial expression of pain: an evolutionary account. Behav Brain Sci 2002;25:439–88.
Amanda C. de C Williams * University College London, Sub-Department of Clinical Health Psychology, Gower St., London WC1E 6BT, UK E-mail address: [email protected] Kenneth D. Craig University of British Columbia, Department of Psychology, 2136 West Mall, Vancouver, BC, Canada V6T 1Z4 E-mail address: [email protected]
*
Corresponding author. Tel.: +44 20 7679 1608.