BIOPSYCHOSOCIAL ASPECTS OF PAIN
Psychological factors have been found to affect many different biological processes too
numerous to describe here. However, one area in which psychology has made a sub -
stantial impact is in understanding the experience of pain and the management of pain.
Early theories of pain did not incorporate a role for psychological factors in explain -
ing how we experience pain. This is surprising given that we can all think of episodes
when someone’s perception of pain has been influenced by cognitive, emotional or
social factors. For example, we are less likely to experience pain when we are
distracted by the demands of taking part in a competitive sporting event.
The role of meaning in pain
The meaning an individual attributes to pain has been found to affect their experience
of it. Beecher (1956) provided striking evidence of the important role of the meaning
of pain during World War II. As a physician he treated many soldiers who had been
badly wounded and found that 49 per cent reported being in ‘moderate’ or ‘severe’
pain with only 32 per cent requesting medication when it was offered. However,
several years later when he was treating civilians with similar if not less severe wounds
after having undergone surgery, he found that 75 per cent of the civilians reported
being in ‘moderate’ or ‘severe’ pain with 83 per cent requesting medication. Beecher
accounted for these stark differences in terms of the meaning the injuries had for
the soldiers compared to the civilian surgical patients. For the soldiers, their injuries
represented the end of their war and they could look forward to resuming their
lives away from the dangerous battleground. In contrast, for the civilians, the surgery
represented the beginning of a long and challenging disruption to their lives.
Two of the early dominant theories of pain perception are specificity theory and
pattern theory. The former theory takes a very mechanistic view and assumes that we
have a separate sensory system for perceiving pain similar to hearing and vision.
Moreover, specificity theory posits that the ‘pain system’ has its own set of special pain
receptors for detecting pain stimuli and its own peripheral nerves, which communicates
via a separate pathway to a designated area in the brain for the processing of pain signals.
Pattern theory offers a competing view. It suggests that a separate sensory system
does not exist but instead receptors for pain are shared with the other senses. Central
to this view is the notion that an individual will only experience pain when a certain
pattern of neural activity reaches a critical level in the brain. Moreover, given that mild
and strong pain stimulation uses the same sense modality, this theory suggests that only
intense stimulation will produce a pattern of neural activity that will result in pain.
Nevertheless, as outlined above, none of these early theories can explain the role
of psychological factors in pain perception. For example, they cannot account for how
cognitive, emotional and social factors such as the meaning of pain can influence the
experience of pain.
Gate-control theory of pain
In 1965, Melzack and Wall introduced the gate-control theory of pain perception.
This theory was innovative as it incorporated important aspects of earlier theories but
BIOPSYCHOSOCIAL PATHWAYS 27