The fix is worse than the problem: A reply to psychedelic researchers

(This rejoinder has been followed by a relevant disclosure and commentary, as well as a follow up essay written by Prof. Kelly).

Several weeks ago, Prof. Edward Kelly (University of Virginia, Department of Psychiatry and Neurobehavioral Sciences) and myself wrote an essay on Scientific American criticizing how recent research on psychedelics has been misinterpreted and misrepresented. Now, six researchers have written a reply to our criticisms, on that same forum. This post is my personal rejoinder: a commentary on, and answer to, their reply.

1. Clearing the semantic fog

First, let us get a semantic point out of the way so we can focus on substance. The researchers state that
neither we [i.e. the researchers] nor others claim that “brain activity randomness” explains psychedelic experiences. Our finding of increased signal diversity is part of a larger mission to account for aspects of conscious experience in terms of physiological processes. (emphasis added)
How is ‘accounting for’ consciousness ‘in terms of physiological processes’ different from ‘explaining’ consciousness in terms of these same physiological processes? Isn’t this just semantic obfuscation masquerading as argument? An attempt to eat the cake and have it too? Be it as it may, let’s just say that what Prof. Kelly and I meant by ‘explaining’ psychedelic experiences is what the researchers mean here by ‘accounting for’ them. This way, we get this word game out of the way quickly.

2. Metaphysical claims

The researchers continue the quote above with the following passage:
In our view, higher signal diversity indicates a larger repertoire of physical brain states that very plausibly underpin specific aspects of psychedelic experience (emphasis added)
Okay. So their work aims at underpinning aspects of the psychedelic experience in terms of brain states. Very well. They then—correctly—define the materialist metaphysics as follows:
… “materialist” views, held by most neuroscientists, according to which conscious experiences—and mental states in general—are underpinned by brain states. (emphasis added)
Right. So the inescapable logical implication of these two passages taken together is clear: according to the researchers themselves, their work supports the metaphysical view of materialism. Yet, they continue:
Our study, like all other studies that explore relations between experiential states and brain states (whether about psychedelics or not), is entirely irrelevant to this metaphysical question. (emphasis added)
What? They go on to say that Prof. Kelly and I espouse
an anti-materialistic view of consciousness that has nothing to do with the details of the experimental studies—ours or others. (emphasis added)
What is one to make of this? Are the researchers again trying to eat the cake and have it too? Either they claim credit for allegedly making progress in explaining—err, accounting for—the mind-body problem in terms of physical brain states, or they acknowledge that they aren’t accounting for it at all, but just charting correlations. They cannot claim the metaphysical credit when they can get away with it—for instance, by systematically allowing the press to do just that in their name, or by directly suggesting it in their own talks and presentations—and then turn around and disclaim it when they need to circumvent criticism. One cannot have it both ways.

But I don’t want to make too much of a meal out of what may be just loose and inconsistent use of words by the researchers. Maybe the point they are trying to make is simply that scientific results do not necessarily entail or imply a metaphysical position; a point with which I wholeheartedly agree. But to say that their observations are “entirely irrelevant” to the mind-body problem—which is a metaphysical problem through and through—is just wrong, betraying a painful degree of naiveté regarding philosophy of mind.

Although scientific observations don’t necessarily imply a metaphysical position, they surely inform metaphysical hypotheses. Metaphysics is not done in a vacuum. While science tries to model the behavior of nature, metaphysics attempts to interpret this behavior so to make educated guesses about what nature essentially is. So scientific observations are very relevant for metaphysics. That there are correlations between brain states and experience reflects a behavior of nature demanding a metaphysical interpretation. That the internal consistency of these correlations sometimes breaks is perhaps even more relevant, insofar as it creates a significant problem for the particular metaphysics of materialism.

3. What the researchers fail to address

In their reply, the researchers discuss, at some length, some of the more detailed technical issues in contention. But they fail, rather conspicuously, to even touch on the elephant in the room. Indeed, a key point of my essay with Prof. Kelly was this:
The problem is that modern brain imaging techniques do detect clear spikes in raw brain activity when sleeping subjects dream even of dull things such as staring at a statue or clenching a hand. So why are only decreases in brain activity conclusively seen when subjects undergo psychedelic experiences, instead of dreams? Given how difficult it is to find one biological basis for consciousness, how plausible is it that two fundamentally different mechanisms underlie conscious experience in the otherwise analogous psychedelic and dreaming states?
Why is this—the opening point of our criticism—not even mentioned by the researchers? Why no commentary at all on the seeming inconsistency between the dream and the psychedelic state? Another important point Prof. Kelly and I made was this:
To suggest that brain activity randomness explains psychedelic experiences seems inconsistent with the fact that these experiences can be highly structured and meaningful.
The researchers even quote this passage of our article in their reply, raising the immediate expectation that they are about to address it substantively. But then their shot is a dud: they simply say that they weren’t trying to ‘explain’ anything anyway (“neither we nor others claim that ‘brain activity randomness’ explains psychedelic experiences”), in a passage I already commented on in Section 1 above. They dismiss the point merely on account of a word they don’t seem to like.

Well, fine, I can change the word. If I re-phrase our original charge—quoted above—by replacing ‘explains’ with ‘accounts for,’ what is their reply? We don’t know, for they don’t provide it. So our criticism stands: How can one account for the highly structured, meaningful experiences of a psychedelic trance in terms of ‘signal diversity,’ which is largely equivalent to randomness? Why don't the researchers address this glaring point, so central to our original criticism?

The researchers also do not counter our charge that they—in ways discussed in our original article and, even more extensively, in two earlier posts in this blog (here and here)—have contributed, either actively or by omission, to the scandalous media misreporting of their findings.

4. A surprising claim

The most surprising passages in the researchers’ reply were these:
These are not the only inaccuracies in the piece that deserve redress. For example, [Kastrup’s and Kelly’s] suggestion that decreased “brain activity” is one of the more reliable findings of psychedelic research is incorrect.
Well, the facts say otherwise. Here is a list—already provided in our original article—of four studies that replicated the salient aspects of the original 2012 findings for multiple psychedelic agents and measurement strategies:
  1. Broadband Cortical Desynchronization Underlies the Human Psychedelic State.
  2. The Psychedelic State Induced by Ayahuasca Modulates the Activity and Connectivity of the Default Mode Network.
  3. Neural correlates of the LSD experience revealed by multimodal neuroimaging.
  4. Two dose investigation of the 5-HT-agonist psilocybin on relative and global cerebral blood flow.
Two of these replications were done by some of the very researchers I am now replying to, so it’s confusing to me that they don’t seem to want to highlight their own successful replications. Moreover, no study I am aware of has contradicted those original findings since their publication in 2012. I believe this is sufficient basis to claim that the findings are now quite reliable. They were certainly “replicated across studies and study teams,” as the researchers seem to demand.

Now the researchers get more specific and claim something that gave me pause:
early reports of decreased brain blood flow under psilocybin have not been well replicated: a subsequent study by the same team using a different protocol and drug kinetics (intravenous LSD) found only modest increases in brain blood flow confined to the visual cortex. (emphasis added)
This is remarkably misleading. That a claim like this is made by some of the co-authors of the very paper in question is even more remarkable. But okay, let’s stick to the facts. I have discussed the paper in question extensively here. I reproduce below the figure in the paper that shows—through direct measurements done with magnetoencephalography (MEG)—whether and where brain activity has increased (red) or decreased (blue) upon intravenous administration of LSD:

No, I am not kidding. Blue represents decreased brain activity. I didn’t create this figure; I downloaded it from the paper in question. Here is the direct link if you want to check it. Contrary to what the researchers claim in their reply, the findings in this paper weren’t “only modest increases in brain blood flow confined to the visual cortex”; they were of widespread decreases in activity throughout the brain.

So what about the “modest increases in brain blood flow”? Next to the direct measurements of brain activity done with MEG, cerebral blood flow (CBF)—an indirect measurement of brain activity—was also measured. Modest increases in CBF confined to a small area in the visual cortex were then indeed found; a small local discrepancy in view of the broad decreases in activity directly measured with MEG. So what did the authors of the paper make of this small discrepancy? Here are their own words, lifted verbatim off their paper:
One must be cautious of proxy measures of neural activity (that lack temporal resolution), such as CBF or glucose metabolism, lest the relationship between these measures, and the underlying neural activity they are assumed to index, be confounded by extraneous factors, such as a direct vascular action of the drug. For this reason, more direct measures of neural activity (e.g., EEG and MEG) … should be considered more reliable indices of the functional brain effects of psychedelics, and it is notable in this regard that our previous MEG and RSFC findings with psilocybin are highly consistent with those observed here with LSD. Thus, rather than speculate on the above-mentioned discrepancy, it may be more progressive to highlight the advantages of EEG/MEG and dynamic fMRI... (emphasis added)
So the authors themselves dismiss these increases in CBF as possible artifacts, expressing confidence only in the decreases in neural activity directly measured with MEG.

What is one to make of this?

5. The issue of statistics

The researchers summarize their main point—on which they base the bulk of their reply—thus:
[Kastrup and Kelly] suggest that the changes in signal diversity we found are “small,” when it is not magnitude but statistical significance and effect size that matters.
They proceed to make a meal of it while ignoring the elephants in the room (see Section 3 above). Nonetheless, let us bite this bullet anyway: statistical significance shows merely that the effect is real, in the sense of not being explainable by experimental artifacts. But we never claimed that the effect isn’t real; that wasn’t our point. Our point was that, insofar as the researchers aspire to explain—err… account for—psychedelic experiences in terms of a change in a measurable physiological parameter, the magnitude of the change measured is indeed relevant. Why? Because the magnitude of the corresponding change in subjective experience is colossal.

You see, from a first-person point of view a psychedelic trance represents a huge—what an understatement—alteration of consciousness, which only those who have undergone it can fathom. So it becomes at least cumbersome to try to account for this colossal subjective effect in terms of relatively small measurable changes in brain physiology, even if these are statistically significant. The researchers don’t address this point. Instead, they create a straw man and proudly burn it down.

6. A non sequitur

The researchers also did not like our claim that there is a formidable chasm between the magnitude of the subjective effects of a psychedelic trance and the accompanying physiological changes. In reply to it, they say:
To claim a “formidable chasm” is to misunderstand the incremental nature of consciousness research (and experimental research generally), to sideline the constraints and subtleties of the relevant analyses and to ignore the insights into psychedelic experience that such analyses provide.
This is a complete non sequitur. There is absolutely no contradiction between (a) acknowledging that incremental progress is being made, with accompanying insights and subtleties, despite constraints, and (b) pointing out that there is still a formidable chasm to be overcome.

7. Final thoughts

Our original criticism wasn’t against the psychedelic research itself. I applaud it and believe such research should continue to be funded and even prioritized. It has important applications, as well as important philosophical implications. Our criticism was against the way the research is routinely and repeatedly misinterpreted and misrepresented. The researchers’ reply, in my view, did not meaningfully address our criticisms in this regard. It left the important points unaddressed, created and burned straw men, got lost in semantic games, and even misled its readership by further misrepresenting the experimental results in question (see Section 4 above). If anything, it has made the situation worse. We, as a community, have missed another opportunity to get the facts straight. Instead, we’ve invested time, effort and media space in becoming more entrenched in earlier errors.


  1. Well said. Sadly, this has to be published separately from the original article and the resultant attack. Four decades ago, Kelly tried to refute a similarly meretricious article by Persi Diaconis in Science; the editors wouldn't publish the refutation. And so on, back to the late nineteenth century. But what can you do but try?

    1. Yes, though we already published the original article on Scientific American. They can't keep on publishing every rejoinder...

  2. Once again more language games. Much of what they specifically wrote was written to give plausible deniability to... well what ever they would need to, as needed. Plus how do you get away with misrepresenting the results of your own replication study?! LOL This is all very odd. For people claiming that their research has no bearing on metaphysics they sure seem pretty concerned about it.

    1. Bob, you always pin down the essence of the issues with such clarity. Ditto!

  3. For me, the following statement made by the researchers puts this debate into proper context: "Our finding of increased signal diversity is part of a larger mission to account for ASPECTS of conscious experience in terms of physiological processes" (caps added). One might argue about whether the findings did indeed show "increased signal diversity," and if so, the nature and possible significance of that increase in light of other measurements, etc. But how could one take issue with the seemingly circumscribed and humble scientific effort to attempt to account, in physical terms, for certain aspects of conscious experience? As they indicate, Bernardo and Prof. Kelly welcome such scientific exploration. What they do not welcome, however, and are vigilant to guard against, is the express or implied stretching of purported results of that modest endeavor (whether by scientists or reporters) into promiscuously broader or deeper explanations of conscious experience. Philosophy is supposed to be that discipline which keeps all others in their rightful place. This particular controversy is simply an example of philosophy performing its duty.

    1. Ditto. I have no issue with the findings of signal diversity (which is randomness, really). But the suggestion that increased randomness can account for any significant aspect of a psychedelic experience simply flies in the face of reason, in my view. These experiences are highly structured and meaningful, as other studies have demonstrated (and anyone who has tripped on psychedelics knows firsthand), and signal randomness will simply not do to account for them. The researchers did not even attempt to counter this argument of our original essay.

  4. So how does any of this relate to the idea that their is a reality to what you call the metaphysical? As I see it, these are molecules, binding to specific receptors, triggering changes in the firing patterns of a small sub-population or neurons. That this causes profound changes to my conscious experience does nothing to further the idea that their is something beyond normal matter and energy (i.e. physical reality) to this. The fact that the ingestion of a small amount of known material molecule can so profoundly change my interpretation of everything does everything to confirm my belief that consciousness is an emergent phenomena of physical reality as described by physics, math, chemistry, biology, and information theory. This ideal of consciousness being other than an emergent property of the universe is to me blasphemous and egotistical. What is this need to be more than a momentary experience of the universe. Really, we are not that important. Or do you also have a place in your world for the soul of my kitty cat? After all, we are all just branches of the evolutionary tree. Or are human souls inserted by god or alien beings after we diverged from the last soulless ancestor? Really!

    1. The depth of your metaphysical naivite is dizzying. Materialism--which you seem to espouse--IS a metaphysics. Alternatives to materialism do not need to postulate anything beyond the type of experiences we ordinarily have, such as perceptions, feelings, emotions, thoughts, etc. You can peruse my videos, academic papers and books for more on all this (all of which are linked to in the top menu bar above).

    2. This reply does need to go into my hall of fame under the category of 'materialist true believer who doesn't understand what materialism is'.

  5. I’m stunned to see Dr. Carhart-Harris attempting to walk back the results of his own research, and neglecting a number of other studies that show broadly similar patterns of brain activity in conjunction with psychedelics. In fact, I'm quite disheartened by his response to this entire debate, especially the frankly trite posts on his twitter in which he repeatedly mocks, insults, and strawmans Dr. Kastrup's and others' positions. I can't help but point out a glaring false dilemma that has been erected in the context of this discussion: that of science vs. any non-reductive or non-physicalistic ontology of the mind-body relationship. This fallacy, which leads to the conflation of the scientific method (an epistemology) and physicalism (a metaphysics), has to be one of the most stubbornly ingrained and pernicious fallacies plaguing intellectual discourse in the West, and on countless occasions I’ve witnessed Dr. Kastrup’s repeated attempts to dispel this notion. It serves to provide an easy strawman of the opponent of physicalism - whether he/or she be an idealist or an proponent of any other non-reductive ontology - as being a “science-denier.” But no parties to this debate are in any way opposed to rigorous empirical inquiry that characterizes the scientific method.

    Regarding replications of decreases in brain activity, I think it’s apt here for me to mention the following studies, which will serve to add to those listed here in this post and in the original Scientific American article. The first two mentioned below were done with animals (i.e., rats), so obviously, we must be cautious when generalizing the results to human beings. However, the data are entirely consistent with the recent research into the neural correlates of psychedelics in humans. (Full references below.)

    A study by Riga et al. (2014) demonstrated that the administration of 5-MEO-DMT in rats disrupted EEG oscillations and resulted in reduced BOLD signal in the visual (V1) and medial pre-frontal cortices.

    Wood et al. (2012) observed that DOI (2,5-dimethoxy-4-iodoamphetamine), a serotonergic hallucinogen similar to LSD, dose-dependently decreased activity in the prefrontal cortex of rats, reducing low (35-55 Hz) and (55-80 Hz) high gamma-band EEG power in the orbitofrontal and anterior cingulate cortices.

    In humans, a study by Kometer et al. (2015) also revealed similar results: “Psilocybin decreased the current source density of neuronal oscillations at 1.5-20 Hz within a neural network comprising the anterior and posterior cingulate cortices and the parahippocampal regions.”

    Lastly, the team at Imperial London College are currently engaged in research into the neural correlates of i.v. administered DMT in human participants. While the findings have not yet been published, preliminary EEG results from this work were presented by Chris Timmermann in a presentation given at Breaking Convention in 2017. Again, based on this presentation, the results are very similar to that of their research on psilocybin, showing large power decreases in the alpha (8-13 Hz) and beta (13-30 Hz) bands of the EEG, as well as observations of increases in signal diversity. Both of these effects seem concentrated in the occipital, parietal, and temporal regions of the brain.

    - Kometer M., Pokorny T., Seifritz E., Volleinweider F. X. (2015). Psilocybin-induced spiritual experiences and insightfulness are associated with synchronization of neuronal oscillations. Psychopharmacology.
    - Riga, M. S., Soria, G., Tudela, R., Artigas, F., and Celada, P. (2014). The natural hallucinogen 5-MeO- DMT, component of Ayahuasca, disrupts cortical function in rats: reversal by antipsychotic drugs. International Journal of Neuropsychopharmacology.
    - Timmermann, C. (2017). Dynamic transitions of consciousness: An EEG study using DMT. Breaking Convention, University of Greenwich, London.
    - Wood, J., Kim, Y., and Moghaddam, B. (2012). Disruption of Prefrontal Cortex Large Scale Neuronal Activity by Different Classes of Psychotomimetic Drugs. J Neurosci.

  6. On a related note BK I wanted to make sure you were aware of the recent piece (Spooky Action) in Scientific American Dec 2018 by Delft U physicist Hanson along with Shalm continuing in even more depth the work of Groblacher in the Nature article 2007 you cite in Materialism is Baloney. I study with Rupert Spira and apply his and your work to the development of acoustic sonic environments that according to participants suspend agency/identity with the effect of disappearing separation for a period of time. We are looking to do a series of studies around this so as to contribute to this overall work. Curated sound experiences using low prime ratios of the harmonic series (proportional harmony vs equal tempered harmony) as the foundation, are forces of nature/superhighways to expanded awareness states especially when combined with sonic omnidirectionality. Frames of reference are upended. It's a non verbal stream of experience, outside language.

  7. For anyone interested in hearing Bernardo discuss his views on what brain imaging reveals regarding brain activity while on a psychedelic trip, and controversy discussed here, and the cultural implications; I highly recommend this interview starting at 1:40:30,