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 fogFirst, 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 claimsThe 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 addressIn 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 claimThe 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:
- Broadband Cortical Desynchronization Underlies the Human Psychedelic State.
- The Psychedelic State Induced by Ayahuasca Modulates the Activity and Connectivity of the Default Mode Network.
- Neural correlates of the LSD experience revealed by multimodal neuroimaging.
- Two dose investigation of the 5-HT-agonist psilocybin on relative and global cerebral blood flow.
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 statisticsThe 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 sequiturThe 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.