Measuring the ineffable: 5 Questions for mystical experience researcher Kurt Stocker

Stocker discusses how researchers measure mystical experiences.

If you’ve ever listened to someone describe their experiences on psychedelics, there’s a good chance you heard about feelings of connectedness with the universe, or transcending time and space. These are part of what researchers call “mystical experience,” and some studies suggest this type of feeling can produce profound and lasting effects in people.

In the resurgence of psychedelic research over the last decade and a half, many researchers have measured mystical experiences in participants by asking them to answer a written survey called the Mystical Experience Questionnaire, or MEQ. The MEQ contains 30 descriptions, like “Experience of unity with ultimate reality” or “Feeling that you experienced eternity or infinity,” and participants rate on a scale of 0 (none) to 5 (extreme) how much their psychedelic experience reflected the statements. The MEQ was originally part of a longer questionnaire, first developed in 1963 by Walter Pahnke, one of Timothy Leary’s graduate students at Harvard. Pahnke created the questionnaire for his dissertation research, which many people now know as the Good Friday experiment, in which 20 divinity students were given psilocybin to examine whether the drug could induce profound religious experiences. Later on, Pahnke, along with psychologist Bill Richards, developed that questionnaire into the Psychedelic Experience Questionnaire, contained more than 100 questions for participants about the feelings and insights they had while tripping.

Recently, Kurt Stocker, a research associate in psychopharmacology at University Hospital Basel and a project leader for psychedelic science at the Federal Institute of Technology in Zurich, began taking a closer look at mystical experiences and grew interested in analyzing the MEQ’s predecessor, which the research team in Basel has renamed the Psychedelic Experience Scale, or PES. (This is because the acronym for its original name, the “PEQ,” is now the name of another questionnaire measuring changes in people’s attitudes, behaviors, and moods after a psychedelic experience.) The Microdose spoke with Stocker about the history and future of these mystical experiences questionnaires and what they might tell us. 

While the Mystical Experience Questionnaire is still in wide use in psychedelics research, that original, longer mystical experiences questionnaire called the Psychedelic Experience Questionnaire, or PES, fell out of fashion. Why did researchers stop using it?

Some researchers used the PES in the 1970s, but psychedelic research largely died off after that – until 1999, when the late Roland Griffiths, and his collaborators, Bill Richards and Bob Jesse, started it back up at Johns Hopkins. Their first milestone study from that research was published in 2006, and they adapted 43 questions from the PES; some people know that as the MEQ43. 

From there, after they reintroduced it, the whole international community only saw those 43 questions; later on, they condensed it down to 30 questions. Many people in the scientific community knew that those 43 questions came from a longer questionnaire, which Griffiths had called the “States of Consciousness” questionnaire. Given the name change, and because the questions of the PES were only published in the 1975 dissertation of Bill Richards, it’s likely the source was hard to get a hold of for other researchers. And I can see why the Hopkins researchers gave the PES, or formerly “Psychedelic Experience Questionnaire,” a different name - those researchers were so brave to restart this research, and maybe they thought it would be better to explore “consciousness” instead of “psychedelics.”

Are there aspects of the mystical experience that aren’t revealed by the MEQ, but are illuminated by the questions in the PES?

The main difference is the measure of connectedness. It sounds a bit cheesy but many, many participants report this deep sense of love. Not the kind of love that you read about in psychology textbooks, but a kind of love that almost feels like a cosmic force: it seems to be everywhere, holding everything together. There are questions in the 43-question version of the MEQ that get at this, so, theoretically, you could get a richer representation of mystical experience with just 10 questions more. If I can persuade people of anything, it would be to use the MEQ 40 instead of the 30 – without those 10 questions, you miss out on some things.

According to researchers, two common hallmarks of a mystical experience are that these experiences are “ineffable” – inexplicable to those who haven’t experienced them – and “paradoxical,” meaning the experience contradicts itself.  With descriptors as nebulous as that, how can any questionnaire or study measure a mystical experience? Are there other common features of mystical experiences that these questionnaires so far cannot capture?

There are some important aspects of the mystical experience which neither the MEQ nor PES, nor any existing scale really fully covers. For instance, some people regress into childhood and re-experience a challenging event. The PES covers this a tiny bit, in that it asks about age regression, but it doesn’t measure whether people, as part of that regression, address a specific problem or experience a specific past event. 

Another aspect that is still missing, which we're trying to measure, is sometimes called the “primal ground,” or “source of all existence.” Many people experience this on psychedelics; you see this in statements from shamanic peoples — like Maria Sabina said she could go to the source, to the place where things are created. Sometimes people have this feeling that they go to the source of all existence. 

What are the tradeoffs between using the PES, a longer and more comprehensive questionnaire, and shorter questionnaires like the MEQ?

If you are a researcher, you have to look at the whole picture of the study. For instance, if you want to know how the distress people experience during a mystical experience correlates with mystical experience, maybe you could use the PES, because it measures both of those things. But it depends on what other questionnaires you are already using, for instance, the challenging experiences questionnaire measures this and you could correlate that with the MEQ. As an example, in some of Griffiths’ studies, participants were filling out multiple questionnaires, so it might not make sense to add in a longer one like the PES. Our long term goal over the next few years would be to build a questionnaire that is at least as concise but a bit more broad.

How are you all currently using the PES, and what’s next for the questionnaire?

We run it standardly on all clinical trials we have with healthy participants, and also patients who suffer from depression or life-threatening anxiety, as well as cancer patients. We want to know if their questionnaire responses correlate with significant outcomes, like a reduction in anxiety or depression. We also want to know if these factors hold for all psychedelics – so far, we have lots of data on mystical experience in people using psilocybin and LSD but less on mescaline or DMT.

I think there’s sometimes this attitude that we have this perfect mystical experience questionnaire, and that's just it. But in the natural sciences, if you study molecules, you don’t just stop — and if you want to study something as amazing as the mystical experience, the study never stops. If we establish the source of all existence as another aspect of mystical experiences, then there will probably be another aspect that pops up. It’s probably not endless, but I think that we can make advances probably for the next two or three hundred years. 

This interview has been edited and condensed for clarity and length.

Correction: We have updated the part of this post regarding Timothy Leary's firing from Harvard. We originally wrote that Leary's work on the Good Friday project was what led to Leary's firing; it was not.