#5: The Placebo Effect:
There’s evidence that several things might be going on with placebos: expectancy, motivation, conditioning, and endogenous opiates.
(1) Expectancy: If we expect to feel pain we are more likely to feel pain. If we are told to expect a strong painkiller, we’re more likely to get pain relief.
(2) Motivation: Patients who are strongly motivated to get well are more compliant and follow health advice more conscientiously. And patients who are more compliant about taking their placebo pills regularly get a stronger placebo response.
(3) Conditioning: People learn to associate pills and medical treatments with relief of symptoms.
(4) Endogenous opiates: Pain-reliving chemicals produced in the brain mimic the effects of opium-like drugs (morphine, etc.). There is some evidence that when patients respond to placebos, their brains produce more of these chemicals. Imaging studies have shown activation of opioid receptors in the brain when people are told that a placebo is a painkiller.