lifestyle, then a placebo in the form of a medical intervention may not work, as the
doctor’s expectation of failure may be communicated to the patient. Furthermore,
theories of health professionals’ health beliefs and their role in doctor–patient com-
munication illustrate a useful emphasis on interaction rather than individual
characteristics.Health-related behaviours
A placebo may function via changes in health-related behaviour. If an individual believes
that they have taken something or behaved in a way that may promote good health,
they may also change other health-related behaviours (e.g. smoking, drinking, exercise),
which may also improve their health. Furthermore, the choice to take a medication
may itself be seen as a health-related behaviour, and may be predicted by theories of
behaviour and behaviour change.Stress
Placebos also have implications for understanding responses to stress. If placebos have
an effect either directly (physiological change) or indirectly (behaviour change) then this
is in parallel with theories of stress. In addition, placebos may function by reducing any
stress caused by illness. The belief that an individual has taken control of their illness
(perceived control) may reduce the stress response reducing any effects this stress may
have on the illness.Pain
Placebo-induced pain reduction may be mediated either by physiological changes,
such as opiate release, or by anxiety reduction. Both of these changes can be explained
in terms of the gate control theory of pain, which suggests that the experience of pain
is a result of an interaction between psychological (beliefs, anxiety) and physiological
(opiates) processes. Previous experience and expectation are also implicated in pain
reduction. Perhaps, placebo-induced pain reduction may also be mediated by patient
expectations and previous experience about the efficacy of the treatment intervention.Implications for dualism
Placebos indicate that an individual’s symptoms and health status may be influenced by
their expectations, beliefs and previous experience. These factors are central to health
psychology in its attempt to challenge the traditional biomedical approach to health and
illness. If an individual’s psychological state can influence their health, then perhaps the
mind and body should not be seen as separate entities but as interacting. This is, in part,
in contradiction to dualistic models of the individual. However, this interaction still
assumes that the mind and body are distinct; to interact with each other, they still need
to be defined as being separate.324 HEALTH PSYCHOLOGY