The Control Group Is Out Of Control

Wiseman & Schlitz’s Experimenter Effects And The Remote Detection Of Staring is my favorite parapsychology paper ever and sends me into fits of nervous laughter every time I read it.

The backstory: there is a classic parapsychological experiment where a subject is placed in a room alone, hooked up to a video link. At random times, an experimenter stares at them menacingly through the video link. The hypothesis is that this causes their galvanic skin response (a physiological measure of subconscious anxiety) to increase, even though there is no non-psychic way the subject could know whether the experimenter was staring or not.

Schiltz is a psi believer whose staring experiments had consistently supported the presence of a psychic phenomenon. Wiseman, in accordance with nominative determinism is a psi skeptic whose staring experiments keep showing nothing and disproving psi. Since they were apparently the only two people in all of parapsychology with a smidgen of curiosity or rationalist virtue, they decided to team up and figure out why they kept getting such different results.

The idea was to plan an experiment together, with both of them agreeing on every single tiny detail. They would then go to a laboratory and set it up, again both keeping close eyes on one another. Finally, they would conduct the experiment in a series of different batches. Half the batches (randomly assigned) would be conducted by Dr. Schlitz, the other half by Dr. Wiseman. Because the two authors had very carefully standardized the setting, apparatus and procedure beforehand, “conducted by” pretty much just meant greeting the participants, giving the experimental instructions, and doing the staring.

The results? Schlitz’s trials found strong evidence of psychic powers, Wiseman’s trials found no evidence whatsoever.

Take a second to reflect on how this makes no sense. Two experimenters in the same laboratory, using the same apparatus, having no contact with the subjects except to introduce themselves and flip a few switches – and whether one or the other was there that day completely altered the result. For a good time, watch the gymnastics they have to do to in the paper to make this sound sufficiently sensical to even get published. This is the only journal article I’ve ever read where, in the part of the Discussion section where you’re supposed to propose possible reasons for your findings, both authors suggest maybe their co-author hacked into the computer and altered the results.

While it’s nice to see people exploring Bem’s findings further, this is the experiment people should be replicating ninety times. I expect something would turn up.

As it is, Kennedy and Taddonio list ten similar studies with similar results. One cannot help wondering about publication bias (if the skeptic and the believer got similar results, who cares?). But 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.

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 gets worse. There's a famous story about an experiment where a scientist told teachers that his advanced psychometric methods had predicted a couple of kids in their class were about to become geniuses (the students were actually chosen at random). He followed the students for the year and found that their intelligence actually increased. This was supposed to be a Cautionary Tale About How Teachers’ Preconceptions Can Affect Children.

Less famous is that the same guy did the same thing with rats. He sent one laboratory a box of rats saying they were specially bred to be ultra-intelligent, and another lab a box of (identical) rats saying they were specially bred to be slow and dumb. Then he had them do standard rat learning tasks, and sure enough the first lab found very impressive results, the second lab very disappointing ones.

This scientist – let’s give his name, Robert Rosenthal – then investigated three hundred forty five different studies for evidence of the same phenomenon. He found effect sizes of anywhere from 0.15 to 1.7, depending on the type of experiment involved. Note that this could also be phrased as “between twice as strong and twenty times as strong as Bem’s psi effect”. Mysteriously, animal learning experiments displayed the highest effect size, supporting the folk belief that animals are hypersensitive to subtle emotional cues.

Okay, fine. Subtle emotional cues. That’s way more scientific than saying “negative auras”. But the question remains – what went wrong for Schlitz and Wiseman? Even if Schlitz had done everything short of saying “The hypothesis of this experiment is for your skin response to increase when you are being stared at, please increase your skin response at that time,” and subjects had tried to comply, the whole point was that they didn’t know when they were being stared at, because to find that out you’d have to be psychic. And how are these rats figuring out what the experimenters’ subtle emotional cues mean anyway? I can’t figure out people’s subtle emotional cues half the time!

I know that standard practice here is to tell the story of Clever Hans and then say That Is Why We Do Double-Blind Studies. But first of all, I’m pretty sure no one does double-blind studies with rats. Second of all, I think most social psych studies aren’t double blind – I just checked the first one I thought of, Aronson and Steele on stereotype threat, and it certainly wasn’t. Third of all, this effect seems to be just as common in cases where it’s hard to imagine how the researchers’ subtle emotional cues could make a difference. Like Schlitz and Wiseman. Or like the psychotherapy experiments, where most of the subjects were doing therapy with individual psychologists and never even saw whatever prestigious professor was running the study behind the scenes.

I think it’s a combination of subconscious emotional cues, subconscious statistical trickery, perfectly conscious fraud which for all we know happens much more often than detected, and things we haven’t discovered yet which are at least as weird as subconscious emotional cues. But rather than speculate, I prefer to take it as a brute fact. Studies are going to be confounded by the allegiance of the researcher. When researchers who don’t believe something discover it, that’s when it’s worth looking into.