WHAT IS PAIN?
Pain seems to have an obvious function. Pain provides constant feedback about the body
enabling us to make adjustments to how we sit or sleep. Pain is often a warning sign that
something is wrong and results in protective behaviour such as avoiding moving in a
particular way or lifting heavy objects. Pain also triggers help seeking behaviour and is a
common reason for patients visiting their doctor. Pain also has psychological con-
sequences and can generate fear and anxiety. From an evolutionary perspective there-
fore, pain is a sign that action is needed. It functions to generate change either in the
form of seeking help or avoiding activity. However, pain is not that simple. Some pain
seems to have no underlying cause and functions to hinder rather than to help a person
carry on with their lives. Such pain has a strong psychological component. Researchers
differentiate between acute pain and chronic pain. Acute pain is defined as pain which
lasts for six months or less. It usually has a definable cause and is mostly treated with pain
killers. A broken leg or a surgical wound is an example of acute pain. In contrast chronic
pain lasts for longer than six months and can be either benign in that it varies in severity
or progressive in that it gets gradually worse. Chronic low back pain is often described as
chronic benign pain whereas illnesses such as rheumatoid arthritis result in chronic
progressive pain. Most of the research described in this chapter is concerned with
chronic pain which shows an important role for psychological factors.EARLY PAIN THEORIES – PAIN AS A SENSATION
Early models of pain described pain within a biomedical framework as an automatic
response to an external factor. Descartes, perhaps the earliest writer on pain, regarded
pain as a response to a painful stimulus. He described a direct pathway from the source
of pain (e.g. a burnt finger) to an area of the brain which detected the painful sensation.
Von Frey (1895) developed the specificity theory of pain, which again reflected this very
simple stimulus–response model. He suggested that there were specific sensory receptors
which transmit touch, warmth and pain, and that each receptor was sensitive to specific
stimulation. This model was similar to that described by Descartes in that the link
between the cause of pain and the brain was seen as direct and automatic. In a similar
vein, Goldschneider (1920) developed a further model of pain called the pattern theory.
He suggested that nerve impulse patterns determined the degree of pain and that
messages from the damaged area were sent directly to the brain via these nerve impulses.
Therefore these three models of pain describe pain in the following ways: Tissue damage causes the sensation of pain.
Psychology is involved in these models of pain only as a consequence of pain (e.g.
anxiety, fear, depression). Psychology has no causal influence.
Pain is an automatic response to an external stimuli. There is no place for interpreta-
tion or moderation.
The pain sensation has a single cause.286 HEALTH PSYCHOLOGY