Placebo Effect 1 Flashcards
Placebo Effect
A genuine physio/psychological response that is not attributable to the actual treatment
3 things that are mistaken placebo effects?
- Natural time course: spontaneous recovery / regression to the mean (go when you feel the worst and you are likely to get better anyway) where effects decline/increase due to natural course of illnesses, mental disorders
- Reporting bias: demand characteristics (respond in a way we think the reporter wants) or criterion/response shift (change scale to report a symptom)
- Behavioural change such as the Hawthorne effect (act of being observed changes behaviour, not the actual treatment)
Kirsch’s expectancy theory
Suggestion and experience create response expectancies and these responses expectancies can produce placebo effects in and of themselves.
When you expect something this has neurological substrengths
The occurrence of a PE reinforces the expectancy on which the PE is based on, i.e. it is self-fulfilling. There is no extinction of PE.
Example of Kirsch’s expectancy theory
having a panic attack before an exam, you expect to have one before the next exam and then you stress about the panic attack etc. etc.
Classical conditioning and the placebo effect
Wickramasekera
Placebo effect occurs when after repeated context CS -> US (context-drug) pairing, the CS (context) acquires the ability to elicit a CR (drug response, e.g. high).
Placebo effect was a conditioned response, repeated context plus drug acquires conditioned response
Example of placebo effect and classical conditioning
Many trips to the hospital, you may associate the hospital with reduced pain (and you may feeling reduced pain without even receiving treatment
nocebo effects vs placebo effects
negative expectancies vs positive expectancies and outcomes
Issues with placebo vs nocebo definition (4)
- positive and negative effects simultaneously
- Who defines positive vs negative
- What about neutral effect? (growth)
- How well can we access people’s expectancies
Placebo in terms of substances
inert (not doing anything) vs active (mimic side effects of actual treatments)
Placebo in terms of procedures
could have surgery or acupuncture (not actually penetrating skin)
What is placebo psychotherapy?
Simply talking i.e. without reliance on techniques underlying psychotherapy
Colaguiri Sleep placebo pill experiment showed ..
Any reduction is above and beyond that could have been expected with no treatment - use controls
Amanzio and Benedetti (1999)
How suggestion influences placebo
Pain test, squeeze grip - causes constriction and pain
Higher scores mean more tolerance to pain
Placebo leads to increased pain tolerance
Reversal of placebo effect when given naloxone implicates the role of endogenous opioids release
Placebo effect vs placebo response
The response to placebo is placebo response, the effect itself is the specific component of the expectancy to get better than makes get better
Pure effect of expectancies
Benedetti et al (2003) Open vs hidden treatment
Either knowing they are getting given morphine or not
Even though the dose is the same, pain report differs whereby
Open morphine produces more analgesia than hidden morphine, i.e. when there is expectancy
When you turn off morphine and tell them this leads to greater increase in pain i.e. when expectancy is removed
Same seen, effects of drugs being better when knowing you are taking it