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and cultural considerations. Pain expression, which may include facial expressions, body
posture, language, vocalizations, and avoidance behaviour, partially represents the complexity
of the psychological experience, but is not equivalent to it (Crombez & Eccleston, 2002; Kunz et al,
2004; Vervoot et al, 2009). Engel’s enunciation (Engel, 1977) of a biopsychosocial model of illness
has provided a framework for considering pain phenomena. A dynamic engagement between
the clinician and the patient was recommended in order to explore possible relevant
biological, psychological, and socio‐cultural contributions to the clinical problem at hand.
The biopsychosocial model of pain (Turk & Monarch, 1995) proposed that biological factors can
influence physiological changes and that psychological factors are reflected in the appraisal
and perception of internal physiological phenomena. These appraisals and behavioural
responses are, in turn, influenced by social or environmental factors, such as reinforcement
contingencies (eg Flor et al, 2002). At the same time, the model also proposes that psychological
and social factors can influence biological factors, such as hormone production, activity in the
autonomic nervous system and physical deconditioning. Experimental evidence supports these
propositions (Flor & Hermann, 2004). Other concepts and models of pain which challenge CHAPTER 1
traditional reductionist, mind‐body or biomedical paradigms have also been promulgated
(Quintner et al, 2008).
1.2.1 Psychological factors
Psychological factors that influence the experience of pain include the processes of attention,
other cognitive processes (eg memory/learning, thought processing, beliefs, mood),
behavioural responses, and interactions with the person’s environment.
Attention
In relation to pain, attention is viewed as an active process and the primary mechanism by
which nociception accesses awareness and disrupts current activity (Eccleston & Crombez, 1999).
The degree to which pain may interrupt attention depends on factors such as intensity,
novelty, unpredictability, degree of awareness of bodily information, threat value of pain,
catastrophic thinking, presence of emotional arousal, environmental demands (such as task
difficulty), and emotional significance. Evidence from experimental studies has demonstrated
that anxiety sensitivity (Keogh & Cochrane, 2002 Level III‐2) and pain catastrophising (Vancleef &
Peters, 2006 Level III‐2) may also influence the interruptive qualities of pain on attention.
Learning and memory
The role of learning or memory has primarily been studied in laboratory settings with
experimentally induced pain. A number of studies using healthy subjects have demonstrated
that reports of pain (eg pain severity ratings) can be operantly conditioned by their
consequences and this effect can be reflected in measures of associated skin conductance
responses, facial activity and cortical responses (Flor et al, 2002; Jolliffe & Nicholas, 2004). Taken
together, these studies provide support for the thesis that the experience of pain is not solely
due to noxious input, but that environmental contingencies can also contribute.
Learning processes may also be involved in the development and maintenance of chronic pain
(Birbaumer et al, 1995). Evidence of both classical and instrumental (operant) learning responses
were reflected in stereotypy, or repetitive movements, of certain muscle groups to personally
relevant stressful situations, as well as conditioning of muscle and pain responses to previously
neutral tones and images.
Beliefs, thought processes
Empirical evidence supports a role for fear of pain contributing to the development of
avoidance responses following pain and injury, which ultimately lead to disability in many
Acute pain management: scientific evidence 7
