Saturday, May 7, 2016

Experimenter Effects

In the study of psychic phenomena, it happens all the time that people who believe in psi get positive results and people who don't get negative results. The general name for this is the "experimenter effect." As Scott Alexander notes,
the phenomenon is sufficiently well known in parapsychology that it has led to its own host of theories about how skeptics emit negative auras, or the enthusiasm of a proponent is a necessary kindling for psychic powers.
But are more "scientific" fields any better?
Other fields don’t have this excuse. In psychotherapy, for example, practically the only consistent finding is that whatever kind of psychotherapy the person running the study likes is most effective. Thirty different meta-analyses on the subject have confirmed this with strong effect size (d = 0.54) and good significance (p = .001).

Then there’s Munder (2013), which is a meta-meta-analysis on whether meta-analyses of confounding by researcher allegiance effect were themselves meta-confounded by meta-researcher allegiance effect. He found that indeed, meta-researchers who believed in researcher allegiance effect were more likely to turn up positive results in their studies of researcher allegiance effect (p < .002).
It is quite remarkable how good we humans are at fooling ourselves, and scientists are no exception.

2 comments:

Shadow Flutter said...

I always wondered why these two scientists didn't do the parapsychology tests together.

Meta
Meta-meta
Meta-meta-meta

A few more metas and we might reach godhood.

G. Verloren said...

The fact that we're so good at convincing ourselves of something seems very handily to go hand in hand with the very real improvements we see once we've been convinced on something.

The placebo effect is staggering - you can see real improvement without treatment simply by being convinced you've been given proper treatment, and you can see real decline despite treatment simply by being convinced the treatment was incorrect or fake. Obviously the best case is for someome to believe in a treatment that they actually do receive, gaining benefit from both avenues.

We also know that a positive attitude helps people overcome illness and injury more readily. A firm belief that one can and will recover actually makes it more likely that a person will recover. We even see such behavior in animals - if something breaks the spirit of a dog or a horse, they can sucumb to illnesses or injuries that they could normally heal with only a modest investment of time, like a broken leg. And yet the biggest threat to such animals with such wounds is that they become depressed and despondant, and refuse to eat and starve.

Would it be a stretch to assume these two phenomenon are linked, perhaps causally? That we're good at convincing ourselves of something we want to believe because it actually increases our chances of survival, and is therefor selected for? If praying makes you feel better, and that leads to increased odds of survival, then isn't religiosity evolutionarily promoted?