7.5.2. How It Works
Nobody knows for sure yet how the placebo effect works, but one theory is that the brain is very sensitive to the presence of social support during the process of recovery from injury and infection. The various components of the acute phase response are all designed to promote recovery and prevent further injury while recovery is taking place. Pain, for example, makes you guard the wounded area. But these measures also have costs; high levels of pain, for example, can actually lengthen the healing process. The brain makes a trade-off between the risks of further damage to the injured area and the delay to the healing process. The presence of social support during recovery shifts the balance between these competing risks because some of the burden of preventing further damage is transferred from the sick person to those around them. The sick person can therefore reduce his own costly self-protective measures, such as pain, and allow the healing process to progress more rapidly.
Another suggestion is that the placebo effect works by means of conditioning (see also [Hack #92] ). Conditioning is a very general kind of learning process in which one stimulus is substituted for another. The classic example is Pavlov’s dogs, which learned to salivate on hearing a bell after Pavlov had trained them to associate the sound of the bell with the arrival of food. In technical terms, an unconditioned stimulus (the sight of the meat), which leads naturally to a certain unconditioned response (salivating at the sight of the meat), is repeatedly paired with a conditioned stimulus (the sound of the bell). Eventually, the dogs learn the conditioned response of salivating at the sound of the bell. Pavlov’s students showed that immune responses can also be conditioned, and others have gone on to suggest that this is what lies behind the placebo response. The unconditioned stimulus is a real drug or some other medical treatment that works even if you have never tried it before and don’t believe in it. The unconditioned response is the improvement you feel after receiving the treatment. The conditioned stimuli are all the things that are repeatedly paired with the treatmentthe size, shape, and color of the pill, for example. If you then take a pill that has the same size, shape, and color as the real one, but which lacks the active ingredient, you may still experience some improvement because your immune system has been conditioned to respond to such stimuli.
Placebos won’t cure the vast majority of medical conditions. It is much easier and quicker to list the things that placebos can influencepain, swelling, stomach ulcers, some skin conditions, low mood, and anxietythan the things they don’t. Everything else is probably not placebo-responsive. That said, placebos are able to help in the management of nearly all illnesses because nearly all illnesses involve pain, low mood, and/or anxiety.
7.5.3. End Note
Hashish I., Harvey, W., & Harris, M. (1986). Anti-inflammatory effects of ultrasound therapy: Evidence for a major placebo effect. British Journal of Rheumatology 25, 77-81.
7.5.4. See Also
Evans, D. (2003). Placebo: Mind over Matter in Modern Medicine. London: HarperCollins.
Dylan Evans
Taken from : Mind Hacks
