The hypothetical experiments presented in the previous post were meant to elucidate the so called placebo effect in somewhat of a guided discovery format. That is, in this case, some observations were presented and the reader was left to draw some logical conclusions. The questions at the end were the “guided” part. Based on reader feedback, my attempt may have been a little too obtuse. Before reading on, read the post if you haven’t already done so.
The small “positive” results from group 1 in both experiments are meant to show that people simply improve over time. That is, bodies heal. Our tissues repair themselves and our immune system takes care of infections. This would happen whether or not treatment had been pursued and these results do not represent a placebo effect. They simply represent what some might call a regression to the mean. Stuff gets better.
In experiment 1, groups 2 and 3 show the progression of an actual placebo effect. As the patient perceives a treatment being administered the reported improvement increases. The more elaborate the treatment, the more pronounced the improvement. In group 4 however, the experiment was meant to show both the effectiveness of the evidence based treatment and that the evidence based treatment may also include more or less of a placebo effect depending on how it is administered.
Experiment 2 is meant to show how reliant the placebo effect is on the subjective nature of both the ailment itself and its symptoms as reported by the patient. In the case of the blood infection, both the ailment and the improvement in symptoms are determined by a completely objective test and hence there is no evidence of a placebo effect.
Finally, the last question asks the reader to think about the potential for self-deception. If you were among the small number of patients with positive results in group 2 in experiment 2, it could be tempting to think that the bacterial infection was actually cleared up by simple relaxation techniques or positive thinking. As a result, it would be likely that you could give a powerful and sincere testimonial as to the efficacy of the treatment and encourage others to try the same. After all, the seemingly effective treatment is completely safe and un-invasive and perhaps even enjoyable. Unfortunately, first hand experience is often the most powerful evidence there is (for the individual involved).
Good examples. At the end of the day because all medical conditions have some amount of neuro-endocrine control the placebo effect comes in to play virtually everywhere. What does not tend to change with placebo is effect size however, which tends to be about the same, apart from in those cases who were a) misdiagnosed, or b) spontaneously resolving.
The placebo effect is a fascinating subject, and you can only really account for it with repeat studies, and large samples. Of course, you are absolutely right, if someone gets better after receiving a placebo, they will tell everyone how well it worked for them. This is why a lot of alternative medicine remains popular.
Additionally, I recently heard an assistant in the pet store advising a customer that the homeopathic pet remedies worked wonders for her dog. In reality, you may as well save your money and give your pet water (which is actually what you are doing anyway).
So interestingly it seems the placebo effect can be vicariously transferred. I.e. if you expect someone else (or even an animal) to get better after a placebo some will. So the placebo effect may also have an influence there ( due to misdiagnosis, regression to the mean, and spontaneous resolution). Some experiments aimed at testing that would be very interesting!
Cheers
Bernie