PubPeer’s Unfortunate Backflip

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PubPeer has reversed and muddied it’s position on site moderation.

Post publication peer review (PPPR) site PubPeer was created for the purpose of enabling discussion of published articles in a manner accessible to the community. And why not? Everyone knows that the success of scientific research hinges on open, critical discussion.

On the other hand…what could be more threatening than open commentary to a research community lacking confidence in the quality of its offerings?

The threat was real, especially due to the fact that PubPeer allowed the names of commenters to be concealed if they so desired. It was well known that criticism of their betters by early career researchers amounted to career suicide, which kept them in line nicely. Meanwhile, the Letters to the Editor category of article, originally designed to enable criticism of published papers, had been effectively neutered, such Letters being almost impossible to publish, reflexively rejected on the basis of tone, lacking “new data” (i.e. not being a regular article), failing to “move science forward.” Add to this the acknowledged fact that contemporary researchers were (and are) failing to meet the bare minimum requirement for their productions to be considered scientific – that is, that their experiments be replicable – and it becomes clear that free critical commentary couldn’t have been more necessary to, or less welcomed by, the research establishment.

Vigilant Scientists

Attacks against PubPeer came in various forms that included a court case brought by an academic who lost a lucrative position at a university thanks to anonymous posts. He demanded PubPeer unmask the critic. What difference could the name of the critic make…well, you know. Fortunately, PubPeer won that case.

Next, a journal editor, flustered by the loss of narrative control, smeared criticism on site as  “Vigilante Science” declaring it a dire threat to the scientific process. PubPeer’s founders  defended their ground in a blog post aptly titled “Vigilant Scientists.” “We believe” they wrote, that

a greater problem, which PubPeer can help to address, is the flood of low-quality, overinterpreted and ultimately unreliable research being experienced in many scientific fields…we believe it is imperative that all possible users of published research be made aware of potential problems as fully and as quickly as possible….The central mission of PubPeer is to facilitate this exchange of information. We…aim to remove barriers and discouragements to commenting.

Apparently parrying complaints that the mere existence of critical comments could damage researchers’ reputations and prospects, they also observed that:

scientists should be able to explain and defend the work they have chosen to publish. And in reality no competent scientist would experience the slightest difficulty in defending their work, if it is defensible…

People who rush to judgment on the sole basis that a comment about some minor detail exists on PubPeer have only themselves to blame. If they are scientists they should definitely know better, and we actively advise readers to form their own opinion of comments.

PubPeer’s original FAQs similarly emphasized that it wasn’t the moderators’ job to ensure the validity of comments, only that they be factual and publicly verifiable.

PP does not review comments scientifically…so factual comments conforming to our guidelines may still be wrong, misguided or unconvincing. For this reason we insist that readers… make up their own minds about comment content.

Signs of Trouble

I was a intensive user of PubPeer, after learning, like many others before me, that the LtE category of submissions was effectively defunct. The site virtually never moderated my posts; once, when inquiring about a post that had been taken down, I was politely told that this had occurred in error and that I was generally very good about following their guidelines.

My strategy with respect to the issues I was concerned with was to target as many of the offending articles as I possibly could. This initially involved vision science, and inevitably led to neuroscience due to the close connection between the two.

For example, I would explain, article after article, why the popular “spatial filter” concept was a non-starter from the get-go. My first blog post  was on this issue and intended to save me having to endlessly repeat myself. Comments were almost never rebutted; and when they were, responses were ineffective and more than a little revealing. Authors often  preferred to communicate via email rather than openly responding on the site.

Another of my pet peeves was the use of arbitrary statistical assumptions in the context of post hoc correlation-fishing, a normalized approach in neuroscience and other fields. My interest in this topic ultimately put me openly at odds with a PubPeer insider and member of this research community, Boris Barbour. A Twitter conversation with him foretold the censorship and bizarre rule changes that were to come.

The views Boris expressed in this conversation were diametrically opposed to the original philosophy of PubPeer. When it came to arbitrary assumptions, he took the view that authors should be givens the benefit of the doubt:

Boris’s comments are in reference to my challenging arbitrary (and untestable) “priors,” a staple of post hoc “Bayesian” analyses. Notice the principle of his objections: He puts the burden on the critic to show that their arbitrariness is a problem, rather than on authors to support, either by argument or evidence, theoretical assumptions that will have a dispositive influence on their conclusions. Readers are supposed to give authors the benefit of the doubt (we shouldn’t “assume the worst”), to trust that the missing rationale exists in the authors’ minds – and that it is sound. Also of note is the indication, in the second tweet, that the untestable prior-based approach, even if akin to p-hacking – is non-negotiable – a choice must be made among alternative “priors.” Boris would apparently be able to live with a critic making any type of argument of this nature, as this would imply buy-in to the approach, rather than a root-and-branch challenge. This reminded me of the situation with LtE’s, in which critics might occasionally be allowed to quibble over alternative versions of dominant paradigms or conventional assumptions, but serious criticism of those paradigms or assumptions as such, however sound, were non grata.

And now, the same goes for PubPeer. Soon after my Twitter conversation with Boris, and without warning – I was grey-listed, and it became almost impossible for me to post the kind of comments that had previously gone unchallenged and been described as following guidelines very well. Asking for the reason, I was merely told that guidelines were “evolving.” Evidently, it was important to begin applying the relevant censorship rules before they had been formally introduced. Many months went by without any changes to the site’s guidelines justifying the new moderation.

The Backflip

Finally, this past May, a rambling, repetitive fine print set of points was appended to the site’s FAQ’s, wholly contradicting the spirit of the moderation expressed in the excerpt quoted above and, at one point, even the letter. Whereas it was originally not the moderators,’ but the reader’s prerogative to judge whether a factual comment was “wrong, misguided or unconvincing,” the position was now that:

Comments that are obviously erroneous or unclear will be rejected, in particular in the context of a series of misguided or potentially malicious comments.

(The two opposing statements briefly co-existed on the site until, perhaps in consequence of tweets I posted flagging the contradiction, the earlier section was excised.)

The vagueness of the language in this excerpt, typical of much of the 482-word addendum, is striking. How clear, how convincing, how relevant or appropriate a comment is are largely subjective judgments; and malice is a state of mind inaccessible to moderators, potential malice not even that. The statement erases all transparency from the moderation process and gives moderators complete, black-box latitude to reject any comment falling outside their personal comfort zone. The architects of the guidelines understand this; it’s not a bug, but a feature of the new, improved PubPeer:

We acknowledge that this is potentially arbitrary, because it depends on the moderators’ expertise.

It doesn’t only depend on moderators’ expertise, obviously limited given the wide range of topics – the entire literature – covered by PubPeer. It depends on the moderators feelings. What could better illustrate the arrogance and lack of principle of the new PubPeer? And what could be the reason for this total rejection of the site’s original commitment to “remov[ing] barriers and discouragements to commenting”  in favor of opaque and arbitrary barriers to commenting – for responding to complaints about unjustifiable censorship by formally asserting a principle of arbitrary moderation?

What else is in the fine print?

Given the open-ended license-to-censor endowed by the 38-word segment quoted above, more additions seem redundant. They’re worth examining nonetheless, as a window into administrators’ attitudes and as attempts at self-justification. (About half the text involves image issues, which I won’t address).

Conspiracy theories and disinformation will be blocked, including links to external sources containing such content.

References to “conspiracy theories and disinformation” are just as vague as references to “unclear” or “misguided” posts. The term conspiracy theory is typically used to discredit, a priori, a point of view unsanctioned by official sources, regardless of evidence for or against; the term disinformation typically refers to false information disseminated by governments for propaganda purposes.  On what basis are judgments on what counts as conspiracy theory or disinformation to be made by PubPeer moderators? We already know they may be “arbitrary;” will they also be independent? Do moderators’ political views now constitute a criterion of moderation?

General comments should be carefully linked to the specific article, and we may limit campaigns making such comments on many papers.

No objection to requiring comments to be linked (carefully!) to the article being critiqued; but the limit on the number of papers to which a relevant comment may be appended by a particular “campaigning” individual is mystifying. What could be the justification for such a stipulation? How many is too many, and why? I’ve been subjected to this restriction, most strikingly when I tried to flag a clearly false assumption promulgated over decades in the case of a recent article by vision science celebrity George Sperling. The comment was just as valid in this case as it was in previous ones, but no way, no how will PubPeer allow it to post. (I’ve been compiling all rejected comments in a separate blog post). In effect, this policy immunizes users of conventional practices from criticism.

Criticism of articles simply for using Bayesian statistics is not considered useful. For such articles, it remains acceptable to discuss alternative choices of prior substantively.

“…not considered useful…remains acceptable…” The stipulation is a reflection of the views expressed in Barbour’s tweets. The problem with “Bayesian” statistics is that there is no objective means of choosing among “alternatives.” This is a very useful point that cannot be made often enough; there is no general defense available to practitioners. The idea that “scientists should be able to explain and defend the work they have chosen to publish” is apparently no longer considered “useful” in the case of this widespread, conventional practice. Protection of indefensible but conventional practices seems clearly to have been on the minds of the moderators when making the adjustments to their FAQs.

Criticism of specific analysis and modelling methods should explain why they are unreasonable/erroneous and significant. This requires engagement with the purpose, design and methods of the article. Appending a brain-dump to a random quotation is insufficient.

This, again, is a barrier to comments with general relevance. It was my practice to flag general issues (like the spatial filtering issue mentioned above) with links to the related blog posts. I don’t know what qualifies, in PubPeer moderators minds, as a “brain-dump.” I also have no doubt that my blog posts were on their minds when they deployed this nasty, dismissive term revealing a hostility previously unexpressed because unjustifiable, but now formalized as (hopelessly opaque) policy.

Last one:

This is not a homework site. Although requests for explanation can be acceptable, you should provide evidence of having tried to understand the relevant sections of the paper (and, if appropriate, the cited literature) and also of understanding the significance of the issue raised. Put another way, we prefer comments that provide expert insight over those that display ignorance.

“We prefer…” Once again, the guideline is vague and, above all, subjective. Who cares what moderators prefer if they can’t articulate – defend – their reasons adequately? Are they really going to censor comments for not rising to what they personally view as the level of “expert insight”? There can be little doubt that the kinds of views that would pass muster in this context would typically be those respecting conventional wisdom. It also appears that the idea that it wasn’t the site’s responsibility to protect against some readers giving too much weight to “minor” or unworthy comments no longer applied. Like Caesar’s wife, it was apparently deemed that establishment productions “must be above suspicion” and “avoid attracting negative attention or scrutiny.”

Is it the tone?

PubPeer actually calls itself “the online Journal Club;” it was supposed to be a place where readers of the literature could participate in discussion of scientific papers as they saw fit, free of the filter of moderator preferences, interests, levels of expertise, biases, emotions, intuitions, etc. And authors could respond as they saw fit. The job of filtering and negotiation was supposed to fall mainly to users of the site and the authors of critiqued articles, supposed to be able to “defend their work if it is defensible.” In my experience, they never rose to the challenge, allies perpetually whining about tone while assiduously avoiding discussion of substance. The following exchange on a PubPeer thread I initiated tells the story in a nutshell:

Notiochelidon Pileata: This reviewer consistently makes aggressive and ill-informed comments on PubPeer. The tone here is completely unnecessary.

Pluchea Kelleri: “Can Notiochelidon Pileata cite clear specific examples where Lydia M. Maniatis’ comments have been “uninformed”?”

“I’ve only found Lydia’s comments to be concise, appropriate and, most importantly, correct. I’d ask that she not change her tone at all.”

(Notiochelidon declined to elaborate).

For reasons as yet undisclosed, PubPeer has jettisoned their original philosophy in favor of its opposite – something worse than the broken review system it was supposed to replace, where at least reviewers had to put some effort in excusing their rejections of critical Letters.

What happened? As discussed, PubPeer was under pressure from the start to protect fragile conventions from public discussion and fragile reputations from challenge, with establishment figures like Susan Fiske bloviating about “methodological terrorists;” but they didn’t fold. Now they have.

Whistleblowers always lose

We should perhaps, also look to the experience of biomedical researcher Paul Brookes to understand what happened to PubPeer. Brookes was the architect of the now-shuttered blog science-fraud.org. The site was basically a form of PubPeer with only one commenter; according to a 2014 Science magazine article, Brookes “cited 275 papers as having apparent problems, such as undisclosed but noticeable slicing of gels, duplication of bands, or the unacknowledged reuse of images.”  “Out of 275 papers discussed, there have so far been 16 retractions and 47 corrections…I found that the public papers have a seven to eight-fold higher level of corrections and retractions.” Brookes often relied on tips from anonymous colleagues.

I’d say Brookes’ activity constituted an important service to the community. But as he well understood, this isn’t how they see it; as soon as his cover was blown, “Brookes stopped posting to his blog, removed all the materials already posted, and confirmed his identity the next day.” The potential impact on his career was dire:

“I am 41 years old, so I have another 25 years of this to go before I retire. I have to continue to get grants, to publish papers, and obviously if there are people out there who are upset with me, then maybe they will review my grants badly, maybe they will review my papers badly. The potential for retaliation is there; there is really no way to get around this.”

Brookes also received legal threats, and thanks to zero support from his university, had to hire his own attorney. As mentioned earlier, PubPeer was actually sued unsuccessfully, with all of the financial burdens and loss of time that entails.

Unlike Brookes, PubPeer, with the help of commenters like Elizabeth Bik,  has succeeded in normalizing the kind of criticism of sketchy images he was forced to renounce. But they don’t seem to have been able to withstand the threats inherent in enabling open criticism when it comes to other issues. Like Brookes, the founders revealed themselves. The reason for this was “to raise money for The PubPeer Foundation, which was quietly registered in California this past December. [Founder Brandon] Stell says the foundation will: encourage and support postpublication peer review; improve PubPeer’s transparency...”  I don’t think it worked.

It’s clear that PubPeer aren’t intending to, because they cannot, enforce their vague, subjective rules in any catholic way. They are merely a pretext for choking off commentary by particular individuals, who are first grey-listed, then monitored closely. If you have questions about why a comment was removed, they point merely you to their FAQs page – clearly no response at all.

 

 

 

Why contemporary neuroscience experiments ALWAYS WORK the first time (and ALWAYS FAIL the second).

The title and text of this post are part of an attempt to clarify and amplify a point I’ve been hammering on in previous posts, i.e. that neuroscience, as it is practiced today, is a pseudoscience, largely because it relies on post hoc correlation-fishing. For this reason, studies (so-called) have no path to failure the first time they are performed, and always fail the second.

As previously detailed, practitioners simply record some neural activity within a particular time frame; describe some events going on in the lab during the same time frame; then fish around for correlations between the events and the “data” collected. Correlations, of course, will always be found. Even if, instead of neural recordings and “stimuli” or “tasks” we simply used two sets of random numbers, we would find correlations, simply due to chance. What’s more, the bigger the dataset, the more chance correlations we’ll turn out (Calude & Longo (2016)). So this type of exercise will always yield “results;” and since all we’re called on to do is count and correlate, there’s no way we can fail. Maybe some of our correlations are “true,” i.e. represent reliable associations; but we have no way of knowing; and in the case of complex systems, it’s extremely unlikely. It’s akin to flipping a coin a number of times, recording the results, and making fancy algorithms linking e.g. the third throw with the sixth, and hundredth, or describing some involved pattern between odd and even throws, etc. The possible constructs, or “models” we could concoct are endless. But if you repeat the flips, your results will certainly be different, and your algorithms invalid.

Which is why the popular type of study I’ve just described is known not to replicate. And while a lot of ink has been spilled (not least in the pages of Nature) over the ongoing “replication crisis” in neuroscience; while we even have a “Center for Reproducible Neuroscience” at Stanford; while paper after paper has pointed out the barrenness of the procedure (Jonas & Kording’s (2017) “Can a neuroscientist understand a microprocessor?” was a popular one); while the problems with post hoc inferences have been known to philosophers and scientists for hundreds of years; the technique remains the dominant one. As Konrad Kording has admitted, practitioners get around the non-replication problem simply by avoiding doing replications.

So there you have it; a sure-fire method for learning…nothing.

 

Rising neurosci star Steve Ramirez admits comparing two brain states probably isn’t like flipping a coin twice. But like his colleagues, he’s willing to pretend it is.

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“We think of it as the brain’s way of flipping a coin twice and landing at heads twice, but you’re spot on that there’s no a priori reason that brain indeed operates in such a quantitative manner.

By a happy accident, I was able to slip into PubPeer the type of comment moderators for several months now have been routinely censoring sans explanation. What happened next shows quite clearly that these comments aren’t being censored because they lack relevance or substance, but because they hit too close to the mark.

In reading over a paper on hippocampal activity by Chen et al (2019)/Current Biology, I had difficulty finding any reference to sample sizes. I thought this was odd, and posted a brief comment about it on PubPeer. Because I’m grey-listed (which happened without warning or explanation), my comments never post right away, if at all. Soon after, I realized that the authors had actually provided sample sizes in figure captions, whereupon I deleted (or so I thought) the comment from my still-awaiting-moderation post. But it ended up posting. So I edited it, modifying it to ask a different sample-size-related question.

I was also curious about how the behavioral data was collected – I didn’t think the text gave enough information on certain issues. The article says that data are available on request, I emailed Steve Ramirez, senior and corresponding author, to make the request.

Surprisingly, his initial response didn’t refer to this request at all; rather, it consisted of a reaction to my PubPeer comment, as follows:

Thank you so much for your email and question! We posted the individual N, stats, and so on in our figure legends, and chose our N values for the histology and behavior based on previous engram papers that demonstrated such N provided sufficient statistical power (e.g. Liu et al, Nature, 2012; Denny et al. Neuron, 2014; Tanaka et al. Neuron, 2014). These N values and the corresponding stats were also taken as a standard for circuit level / behavioral optogenetic papers (e.g. Tye et al. Nature, 2012; Stuber et al. Nature, 2011) in which we compare across animals for histology and utilize, for instance, a T-test, or across animals and across light on-off-on-off epochs for behavioral data and utilize two-way anovas with repeated measures.

That said, I’d be more than happy to help in any capacity hereafter and thank you again! Other groups have analyzed their data with both similar and diverging sets of statistics and corresponding justifications for such analyses that, too, have yielded pleasantly nuanced results that I’m always thrilled to chat about and brainstorm over. I hope you had a wonderful Thanksgiving and upcoming holiday season as well!

I didn’t find his answer very satisfactory – all he was doing was passing the buck, but I what I really wanted was the dataset, so I simply thanked him for his comments and asked again, saying:

Thanks for your reply, I’d also be happy to chat about the issues you mention, but in this email I was just asking for the info that, at the end of your article, under “Data and software availability,” you say can be made available:

“For full behavioral datasets and cell counts, please contact the Lead Contact, Dr. Steve Ramirez (dvsteve@bu.edu).”

Steve replied:

Absolutely! Are there any in particular I can send your way? They’ll all be straightforward and annotated excel files too to make life easier — always happy to share and help!

I replied that I’d be interested in the behavioral data.

Meanwhile, having been able to edit my PubPeer comment once, and in light of Steve’s enthusiastic reaction to my first one, I went back in and added some more comments. These edits apparently flew under the moderators’ radar; they typically would have nipped such comments in the bud, (as in fact they did a little while later).

Steve responded enthusiastically both to my request and to my new comments, which he evidently found valuable. What follows are his complete responses, which included excerpts from my PubPeer comments (which I’ve placed in italics) and his replies. I’ve bolded a few sections for emphasis, and added some reactions.

Absolutely. I’ll send [the dataset] over shortly (on my commute to work) when I’m back on my work laptop, and in the meantime I’d be very happy to clarify some points raised on pubpeer — thank you so much for the comments, as these always help us to continue to perform as rigorous of science as possible. Very much appreciated!

Steve delayed, then left the country without sending the dataset, assuring me when I followed up that he would send it when he got back.  I think he may have realized that I  intended to look at it critically. (After not receiving it I emailed Current Biology, but it looks like they’ve decided not to respond either). He did, however, respond to my comments point by point:

In order:

The authors say that: “No statistical methods were used to determine sample size; the number of subjects per group were based on those in previously published studies and are reported in figure captions.” To which previously published studies the researchers are referring, and on what basis do they consider those studies’ sample sizes to be valid? If they (or their editors) don’t feel that sample sizes should be selected based on some type of statistical test, then why mention this issue at all? If it is important, then the reference to other, unnamed previous publications is rather inadequate.

Addressed in previous email – thank you again! [See above]

As mentioned earlier, all the email does is pass the buck – and if you dig back you find that there’s no there there, either.

“Exploration of the context while off Dox increased eYFP-expressing (eYFP+) cells in both the dorsal and ventral DG relative to on-Dox controls (Figures 1G, 1H, 1J, and 1K). The following day, mice that explored the same context showed a significant increase in the number of overlapping eYFP+ (i.e., cells labeled by the 1st exposure) and c-Fos+ cells (i.e., cells labeled by the 2nd exposure) in the dorsal but not ventral DG (relative to chance overlap)…”

How is “chance” ascertained here? The brain is highly-condition-sensitive, to both external and internal events, in ways we don’t understand. There’s really no possible “no context” condition; and there was no “explored a different context” control. When the mice are returned to their normal cages, they are also returning to familiar territory; when they are being moved from one place to another, these may also be familiar experiences. All of this affects the brain. Given our level of ignorance about the brain and the countless confounds, I don’t see what the authors could validly be using as their “chance” baseline.

I 100% agree that chance is a tricky thing when it comes to the brain, since it’s a statistical measure applied to a system as complex as the brain, in which we don’t know what true chance would look like. So in that sense, we took the next best approach and utilized statistical chance, i.e. the odds of a set of cells being labeled by one fluorophore (N[number of cells labeled] / Total number of cells in the area) multiplied by the odds a set of cells are labeled by the second flourophore (N[number of cells labeled] / Total number of cells in the area), and we use the resulting number as statistical chance. We think of it as the brain’s way of flipping a coin twice and landing at heads twice, but you’re spot on that there’s no a priori reason that brain indeed operates in such a quantitative manner.

What Ramirez is admitting here is truly, and I mean truly, astonishing. He’s saying that two sets of measurements are being compared on the assumption that these measurements of a bunch of neurons – whichever bunch of neurons we choose to record from at whatever time we choose to record from them – out of the billions of neurons in an organ we don’t understand  – will be distributed in the same random, decontextualized way the results of a series of coin flips would be distributed. We have no reason for making the assumption – but hey, we’ll just do it anyway! Steve doesn’t seem to think there’s anything wrong with that, or anything embarrassing about admitting it.

“Together, these data demonstrate that the dorsal DG is reactivated following retrieval of both a neutral or aversive context memory, whereas cells in the ventral DG show reactivation only in a shock-paired environment.” Sentences like this should raise alarm bells. They are passive (they don’t corroborate or falsify predictions made before examining the data) descriptions of correlations in a sample examined post hoc, meaning they can’t count as evidence of causal connections. In other words, data analyzed in this way can’t be taken to “demonstrate” anything. Claims are as speculative post as they were prior to experiment.

I again totally agree here and thank you for the great point! I have no idea what causality truly would look like in the brain or what a ground truth looks like when it comes to a principle of the brain, and we hesitate to use the word “causality” for that reason. I believe most of our data our correlative or can be interpreted as a result of a given perturbation, but this by no means has to equate to causal. I do believe that term gets thrown around a lot these days with optogenetic / chemogenetic studies, and the reality is that once we perturb an area and networks respond accordingly, perhaps causality can be observed as a brain-wide phenomenon which we’re just started to test out thankfully.

He has no idea how the brain works (“what causality would truly look like in the brain”), yet in the paper he is making assertions about how one thing affects another – assertions about causal relationships. He doesn’t seem to see the contradiction.

In addition: “Post hoc analyses (Newman-Keuls) were used to characterize treatment and interaction effects, when statistically significant (alpha set at p < 0.05, two-tailed).”According to graphpad.com, maker of Prism, one of the software packages employed in this study: “It is difficult to articulate exactly what null hypotheses the Newman-Keuls test actually tests, so difficult to interpret its results.” And from the same source: “Although the whole point of multiple comparison post tests is to keep the chance of a Type I error in any comparison to be 5%, in fact the Newman-Keuls test doesn’t do this.”

“Acute stimulation of a fear memory via either the dorsal or the ventral DG drove freezing behavior and promoted place avoidance (Figures 2I, 2J, 2L, and 2M). Acute stimulation in the female exposure groups promoted place preference but did not affect fear behavior (Figures 2I, 2J, 2L, and 2M).”

While the hippocampus clearly has a role in enabling memory formation and/or retrieval, it cannot possibly contain memorie. Even if we take Chen et al’s report at face value, all we would be able to say is that certain cells display a certain type of activity when the mouse has a sharp fear reaction, and also may instigate an acute fear reaction when stimulated. The claim that this activity is causing the mouse to experience mental imagery corresponding to some particular “context” – out of the infinite number and variety of contexts a normal mouse may experience in its lifetime – is a bridge too far. There aren’t enough cells in the hippocampus to accommodate all possible “contexts.” The authors need to be a little more modest in their claims.

I couldn’t agree more! I personally think that memories are a distributed brain-wide phenomenon in which circuits and networks utilize spatial-temporal codes to process information, as opposed to having a memory localized to a single X-Y-Z coordinate point. Even within the hippocampus with over 1M cells, the permutations possible of a defined set of cells utilizing a temporal code to process contexts is an astronomically, perhaps wonderfully, big number of experiences that it can be involved in — not to say that therefore memories are located in the hippocampus because it technically can process them, but that it’s contribution to enabling numerous memories I don’t believe has an upper limit that we know of, but this is total speculation on my end! However, I do actually believe that our set of experiments beginning with Liu et al. 2012 up to 2019 really hint that we can partly predict what the animal’s internal “experience” (used very loosely here) is actually like (see Joselyn et al. 2015 Nature Neuroscience) for a fantastic review. In short, we “tag” cells active during a defined period of time, say, exposure to context A, and we’ve done numerous experiments that suggest these cells are specific to that environment with minimal “noise”, i.e. without other contexts that the animal experiences spilling over, given the time period of our tagging system. And when we manipulate these sets of cells, the animals show fear responses specific to that context, i.e. Figure 3 of Chen et al., that suggests that at least some aspects of context A are coming back “online,” which dovetails which previous data from a 2013 false memory paper we had as well. That said, I’m fully on board that we’re not at the stage where we can say with certainty what the animal’s mental imagery looks like, though a handful of papers from the Deisseroth lab recently have hinted that we can really force a mental “image” to come back online and force the animal to behave as those it’s experiencing that image. In our hands, we believe that stimulating these cells in the hippocampus has a sort of domino effect in which downstream circuits become activated and this ultimately leads to memory recall, and that the hippocampus is a key node involved in bringing the brain-wide networks involved in memory back online. So it’s not that the memory is located in the hippocampus, it’s more that the hippocampus contains a set of cells which, when activated, are sufficient to activate memory recall by engaging the rest of the systems in the brain involved in that discrete experience too.

Notice that he never addresses the basic point about problems with the Newman-Keuls test, right at the top. Notice also that his claims are far more vague and speculative than his published paper makes it sound.

I hope this helps and thank you again for the fantastic back and forth!

I was actually avoiding getting into a back and forth until I got the dataset. I waited three days, then wrote this:

Just following up on the dataset request.

Thanks for your responses; I think it would be useful if I incorporated them into my PubPeer comments.

I waited several more days in case he wanted to object to the use of his comments in the PubPeer thread, but received no further response. I went ahead and posted his replies on PubPeer. I was truly amazed  by them – not because I didn’t already know the score when it comes to contemporary neuroscience practice, but because I couldn’t believe how casually he admitted what to me was obvious malpractice. He apparently took me for an insider with (compromised) skin in the game, and dropped his guard. I began tweeting right and left, hoping to raise just a tiny bit of the concern and indignation I feel over this state of affairs. PubPeer got wind of my post and duly removed both my original comments (no part of which they allow to be reposed) and Steve’s cheerful, appreciative responses. I suspect Steve or allies got in touch with them and, despite his private candour, made sure PubPeer readers, and outsiders in general, wouldn’t learn about neuroscience’s coin-flipping approach to science.

As seen in a previous post, the ability to tolerate not knowing what you’re doing  or privileging career over good practice, or playing casino statistics, or adopting absurd, though “traditional,”  assumptions, etc, seem to be prerequisites for contemporary neuroscience practitioners.

 

Bad for science? Why did PubPeer reject these comments?

After having posted hundreds of comments on vision science and visual neuroscience without a problem, I was suddenly grey-listed by PubPeer without explanation, without apparent reason. Requests for clarification of moderation criteria go unanswered. It’s now a virtual sure thing that my comments won’t post. Below is an ongoing list of comments. as they’re rejected, with most recent additions added first. Update: PubPeer has added to its FAQs, without revising the earlier ones, which they flatly contradict. For example, “PP does not review comments scientifically (see above), so factual comments conforming to our guidelines may still be wrong, misguided or unconvincing. For this reason we insist that readers… make up their own minds about comment content” vs. new stipulations giving moderators license to bar comments deemed “misguided” “erroneous” “unclear” “potentially malicious” “disinformation,” w/out explanation, and admitting decisions may be “arbitrary” due to lack of moderator expertise. Update 2: Two days after contradiction was pointed out on Twitter, PubPeer removed its  open commenting stipulations. In practice, they now reject even publicly verifiable and relevant information (see below) without specifying what their objection is.

Alessandro Soranzo , Steph Acaster , Naira Taroyan , John Reidy

“Anchoring theory (Gilchrist et al., 1999), for example, gives an account of the way in which mid-level processes, including perceptual grouping-based frameworks, can account for contrast. Assimilation, on the other hand, is attributed to a “relatively low-level kind of space-averaged luminance” mechanism (Gilchrist et al., 1999, p. 802) and, therefore, explicitly not accounted by the theory….These mechanisms may involve both anchoring processes, favoring contrast effects…”

Important here to note that Gilchrist et al’s (1999) “anchoring theory” account of lightness contrast has, in fact, been falsified (Maniatis (2015) https://jov.arvojournals.org/article.aspx?articleid=2289170), and thus cannot explicitly account for either assimilation or contrast.

Keysers, Gazzola, Wagenmakers (2020) Nature Neuroscience[Second attempt;]“This inherent limitation of P values impedes our ability to draw the important conclusion that a manipulation has no effect and hence that a particular molecular pathway or brain circuitry is not involved or that a particular stimulus dimension does not matter for brain activity.”This premise exhibits a certain lack of understanding of the nature of living systems, i.e. that they are highly malleable physically and functionally. If one normally active pathway is impeded another can take its place and the effect in question may remain unchanged. It’s the basis of homeostasis. (Even some machines are capable of this type of thing some degree.) If I’m holding a book and you pile a few more books on top, the position of my hands may not change, but this won’t mean that the added weight had no effect on the function of my muscles and other systems. Of all biological systems, the brain is probably the most malleable and adaptable in the shortest frames. Given, furthermore, that the type of effects of neurophysiological manipulations being discussed here (and as is generally the case in contemporary neuroscience studies) are behavioral, such “behind the scenes” compensatory events won’t be visible.So there seems to be a fundamental flaw in the basis of Keysers et al’s subsequent arguments. [First attempt]“Fisher argued that a low P value signals that “either the null hypothesis is false, or an exceptionally rare event has occurred.”6″Is this a direct quote from Fisher? Or a paraphrase? It isn’t clear given that reference “6” is toWagenmakers, E.-J. et al. The need for Bayesian hypothesis testing in psychological science. in Psychological Science Under Scrutiny: Recent Challenges and Proposed Solutions (eds. Lilienfeld, S. O. & Waldman, I.) 123–138 (Wiley, 2017).If it is a direct quote (or even if it isn’t), could the authors please provide a reference to the original Fisher discussion? Also, it is customary for quotes to be accompanied by page numbers. 

Andersen et al (2020) Nature Neuroscience[This is an article that tried to dismiss out of hand the idea that COVID may have originated in laboratory activities, a view which was always credible and is now becoming even more so. Several comments have already been posted, by me and others, but this last one was barred.]”It has a furin spike protein that is unusual in that it makes Sars-cov2 highly infectious to humans. A furin spike is the reaching out molecule of the virus that is attracted to the host cells. Which is strange b/c zoonotic jumps are, by definition, not highly infectious b/c the viral fit to the new host [humans in a zoonitic jump] is barely enough to accomplish the jump. In Sars-cov2 this is a very specific alteration. It would be like cultivating heirloom tomatoes to grow in a specific type of soil they don’t usually grow in. It would take some tinkering to get it to work. “

Geleris et al (2020) New England Journal of Medicine

Attempted comment on PubPeer “Bug Report” thread May 8/2020

Guest & Martin (2020)/Psyrxiv

Musall, Kaufmann, Juavinett, Gluf, Churchland (2019)/Nature Neuroscience“We characterized movements…and measured neural activity…Cortex-wide activity was dominated by movements, especially uninstructed movements not required for the task. Some uninstructed movements were aligned to trial events. Accounting for them revealed that neurons with similar trial-averaged activity reflected utterly different combinations of cognitive and movement variables.“In the first bolded section above, the authors seem to be making two huge claims. First, that activity across the cortex of their subject animals was “dominated” – meaning, presumably, was responsible for, or caused – the movements observed; and second, that they are in a position to interpret that neural activity as subserving movement rather than mental events, emotions, perceptual events, etc.Similarly, when they state, in the second bolded section, that activity reflected different combinations of cognitive and movement “variables,” one has to ask how they are in a position to parse neural activity in this way. Their method is based purely on observing behavior; they’re not in a position to observe animals thinking.

John Greenwood & Michael Parsons (2020)/PNAS“The visible contours in these elements enabled the perception of motion wtih minimal ambiguity given their orientation variance (i.e. avoiding the aperture problem; ref 24 [Adelson & Movshon (1982)]”I would ask the authors to clarify in what way A & M (1982) supports the claim of “minimal ambiguity” in their stimuli.In the stimuli used by Adelson and Movshon (stripes in circles), ambiguity is maximal; a set of stripes seen through a round aperture will be seen as moving perpendicularly to their long edges regardless of the true direction of motion. Moreover, their stimuli also have “visible contours” – the long edges of the stripes, which appear incomplete, cut off by the edge of the aperture. Looking at G & P’s illustrations, it is clear that many of their stimuli similarly consist of figures with visible long contours that are perceptually incomplete, as if cut off by the edges of the aperture. In other words, their stimuli contain wonky stripes, instead of simple, straight-edged stripes (whose behavior, perceptually, may be more complex than that of the latter). So, again, I’m not sure where the claim of “minimal ambiguity” is grounded.

George Sperling , Peng Sun , Dantian Liu , Ling Lin (2020) Psychological Review [Attempt #1] In their “Theory of the perceived motion direction of equal-spatial-frequency-plaid-stimuli” the authors have forgotten to add one more important qualifier. The correct title should be “Theory of the perceived motion direction of equal-spatial-frequency-plaid-stimuli viewed through a circular aperture.” The authors are treating the perceptual effect of viewing this type of figure through a round aperture as the general case, when, as has been known at least since Wallach (1935), the shape of the aperture has a dispositive effect on the direction of perceived motion. The same set of bars, for example, that seen through a round aperture appear to be moving perpendicularly to their length will, when seen through a rectangular one, appear to be moving along the edge of the aperture (as in the barberpole illusion.)[Attempt #2] The authors need to qualify their claims, which are tailored to apply only to circular apertures. It is well-known that perceived motion direction varies substantially with aperture shape.[Attempt #3] In the first sentence of their abstract, the authors state that: “At an early stage, 3 different systems independently extract visual motion information from visual inputs. At later stages, these systems combine their outputs.”It sounds as though they’re relating matters of fact, or, at worst, matters of accepted, well-corroborated theory. But this is not the case. This seemingly solid base is actually a reference to an old conjecture, for which only one rather old reference is provided:”Three motion systems have been proposed for human vision, (e.g. Lu & Sperling, 1995a).”The term “proposed” constitutes a clear signal from the authors of the still highly-conjectural status of the claim, while no further citations are offered vis a vis subsequent experimental corroboration or replication of the initial proposals and results. Clearly, the single experimental Lu and Sperling paper isn’t enough to establish such an ambitious claim. Thus, I would caution that the statements quoted above are misleading.”[Attempt #4]”There is intrinsic ambiguity in determining the motion diretion of a one-dimensinal stimulus, such as a sine-wave grating. Consider a snapshot of a sine-wave grating displayed on a peice of paper, and the paper is set into motion. Observing through a circular window, the motion is perceived as being perpendicular to the orientation of the grating no matter what arbitrary direction the piece of paper may be physcially moving in. Indeed, all directions of motion of the paper that happen to have the same motion component perpendicular to the stripes of the grating produce precisely the same image inside the aperture…This is the “aperture problem.”Sperling et al’s description of the “aperture problem is incomplete and possibly misleading, as it refers only to a “circular window.” When the window is not circular, then what is perceived may well not be “perpendicular to the stripes of the grating,” but will vary widely depending on the shape of the aperture (Wallach, 1935).[I would add that “equal-spatial-frequency-plaid-stimuli” have precisely zero special status in visual perception. They are a zombie historical artefact kept alive because it makes the math easy (as does limiting discussion to circular apertures). The idea that there are “plaid processing” systems is correspondingly artificial. “Theories” like these don’t generalize even a little bit to ordinary conditions, but they have been the norm for many decades now.]

Barlow (1972)

“In his influential article, Barlow employs what Romain Brette (2019) calls the “coding metaphor” of neural function. Brette is highly critical of this metaphor, and offers cogent logical objections.”

[I believe Barlow’s paper is considered “seminal,” it’s still being cited, and Brette’s critique shows how it’s basic premise is nonsense. He wasn’t the first – Teller also criticized it. PubPeer is evidently protecting a “sacred beast” at the expense of contemporary theoretical critics.]

Weiss, Simoncelli & Adelson Nature Neuroscience

[This next comment is interesting because the moderator included a note explaining why the comment was censored. The moderators comment was: “claims an important assumption is invalidated, but doesn’t explain what the assumption is or why it is important for the analysis or what the analysis is.” I’ll leave it to readers to judge whether I “explain what the assumption is.” As with the Nakayama comment above, the substance is identical to comments I have made on a number of papers repeating the same erroneous “fact.” My question is, why is a PubPeer moderator treating a comment on the site like a reviewer of a letter to the editor, (and without expertise in the particular topic, to boot?) The comment clearly isn’t frivolous; and is explicitly not the role of PubPeer to micromanage content. I subsequently attempted to make the comment more explicit, in case this helped, but the moderator is determined that the same comment I posted for the Adelson & Movshon (1982) “classic” (blogged here) won’t be allowed to post on Yair et al.]

“The integration process is essential because the initial local motion measurements are ambiguous. For example, in the vicinity of a contour, only the motion component perpendicular to the contour can be determined (a phenomenon referred to as the‘aperture problem’)2,4–7.”

The quote above, in particular the bolded section, mirrors a common misunderstanding about aperture motion. Among the citations provided two – 4 and 5 (Wuerger, S., Shapley, R. & Rubin, N. On the visually perceived direction of motion by Hans Wallach: 60 years later. Perception 25, 1317–1367 (1996); Wallach, H. Ueber visuell whargenommene bewegungrichtung. Psychol.Forsch.20, 325–380 (1935), contradict it, in the sense that they clarify that it is not valid as a general statement, applying to circular apertures but not, for example, to oblong ones (as we may easily confirm in the case of the Barberpole Illusion). As such, it lacks the generality that the authors imply it to possess.

Similarly:

“When viewing a single drifting grating in isolation, subjects typically perceive it as translating in a direction normal to its contours (Fig.1b).”

Again, the authors fail to mention the shape-contingency of the perceived direction of motion, making what appears to be an invalid general statement. Their analysis and proposals seem intended to be general – they are offering “a model of visual motion perception.” Given that a fundamental assumption on which the analysis rests is based on a claim about aperture motion that is easily falsified (given differently-shaped apertures), the proposals offered here, whether or not they may be said to apply to the special case, will likely not apply to the general case.”

[Another important thing to note here is that, as in the case of Adelson & Movhson (1982), Weiss et al adopt a false fact because it makes the math easier. If they were to attempt to address the true nature – as illustrated by known fact – of the phenomena they’re purporting to model, the tools – concepts and techniques – they currently have at their disposal would be next to useless. The false fact was inherited by the pro “bayesian” contingent for the same reasons it was adopted originally. All of “computational neuroscience” functions this way. As was made explicit by Carandini et al (2005), blogged here, choices of assumptions are made less based on their validity and more on whether they render the math “tractable.”]

Nakayama (1985) Vision Research

[The content of this comment is identical to that of several comments I have succeeded in posting on PubPeer. I have to wonder whether the status of the author made it too sensitive this time? The issue is very straightforward.]

“This is one of many papers which refer to a special case of aperture motion perception as though it were the general case:

[Nakayama says] “This is essentially equivalent to viewing a moving object through an aperture. Suppose an extended line moves through this aperture [see Fig. IO(A)]. The velocity in the aperture can be described by VL, the local velocity orthogonal to the orientation of the line.”

What Nakayama is referring to as the “local velocity” is the apparent velocity of a line moving within a circular aperture. The text doesn’t specify that the statement is restricted to circular apertures – on the contrary, the discussion is framed in terms of general principles of perceived motion. The distinction is important, since if we were talking about an oblong aperture, the “local motion” would not be “orthogonal to the orientation of the line,” and the equations and inferences offered would not hold. As explained by Wallach (1935), a paper Nakayama cites, the direction of local (i.e. perceived) motion is highly contingent on aperture shape.”

Chen et al (2019) Current Biology

This latest case is perhaps the most interesting and revealing, and I’ve written a separate blog post about about my original post – which went up briefly, as well as the senior author’s extended emailed responses. I tried again with the comment below, which was censored:

“McNish et al (1997) Journal of Neuroscience: “Post-training lesions of the dorsal hippocampus attenuated contextual freezing, consistent with previous reports in the literature; however, these same lesions had no effect on fear-potentiated startle, suggesting preserved contextual fear. These results suggest that lesions of the hippocampus disrupt the freezing response but not contextual fear itself.”

Chen et al have not discussed the distinction being made above, in the cited article and elsewhere, but seem to be using freezing as an operational definition of contextual fear.”

I tried yet again, isolating a simple comment about the statistical tests used – a comment the senior author admitted via email was legitimate:

Jun, Ruff, Tokdar, Cohen & Groh (2019) biorxiv

“In both experimental datasets, drifting gratings were presented at locations that overlapped with the receptive fields of the recorded V1 neurons.”

I can’t find where the authors describe how they determined the recorded neurons “receptive fields.”

Because this is a post hoc re-analysis of two older papers (Ruff and Cohen (2016) and Ruff, Alberts and Cohen (2016)), referenced in the Results section of this paper, I checked those, too, for information. But like Jun et al, no methodological descriptions and no citations are provided to clarify either technique or rationale.

Pack, Livingstone, Duffy & Born (2003) Neuron

“Humans and other primates are able to perceive the speed and direction of moving objects with great precision. This is remarkable in light of the fact that, at the earliest levels of the visual system, local measurements of velocity are often confounded with the object’s shape. The problem is based on simple geometry: if the middle of a moving contour is viewed through a small aperture, only the component of velocity perpendicular to the contour can be recovered Wallach 1935, Wuerger et al. 1996.”

The claim that, as a general principle, “only the component of velocity perpendicular to the contour can be recovered” when seen through a “small aperture” is false, and it is not made by Wallach (1935) (or the intro to the English translation in Wuerger et al (1996)), who emphasizes the importance of the shape of the aperture, not its size.

The claim is applicable to circular apertures; as we can see from figure 1, the aperture characteristics of small size and circular shape are confounded in this analysis. The relevant distinctions need to be made if the theoretical discussion is to be well-founded.

This paper is cited uncritically by the one commented on below, as well as over 100 others.

Hataji, Kuroshima & Fujita (2019) Scientific Reports

Musall, Kaufmann, Juavinett, Gluf & Churchland (2019) Nature Neuroscience

“We characterized movements using video and other sensors and measured neural activity using widefield and two-photon imaging. Cortex-wide activity was dominated by movements, especially uninstructed movements not required for the task. Some uninstructed movements were aligned to trial events. Accounting for them revealed that neurons with similar trial-averaged activity often reflected utterly different combinations of cognitive and movement variables.”

In the first bolded section from the section of the abstract quoted above, the authors seem to be making two huge claims First, that activity across the cortex of their subject animals was “dominated” – meaning, presumably, was responsible for, or caused – the movements observed; and second, that they are in a position, as investigators, to interpret that neural activity as subserving movement rather than mental events, emotions, perceptual events, etc.

Similarly, when they state in the second bolded section, that activity reflected different combinations of cognitive and movement variables, one has to ask how they are in a position to parse neural activity in this way. Their method is based purely on observing behavior; they’re not in a position to observe animals thinking.

  Van Zyl (2018) New Ideas in Psychology 

It is my understanding from reading various texts that the chief distinction made by “Bayesians” between their practices and those of “frequentists” is that frequentists are referring to the actual probabilities or relative probabilities of events resulting from a test of a predictive hypothesis, while “Bayesians” are referring to “subjective” probabilities encompassing a much broader framework (extending beyond the experimental test).

While there have been attempts to carve out a distinction between “objective” and “subjective” “Bayesian analysis,” these efforts seem, so far, unconvincing. I quote below from the Wikipedia entry on “Bayesian probability”:

“Broadly speaking, there are two interpretations on Bayesian probability. For objectivists, interpreting probability as extension of logic, probability quantifies the reasonable expectation everyone (even a “robot”) sharing the same knowledge should share in accordance with the rules of Bayesian statistics, which can be justified by Cox’s theorem.[2][8] For subjectivists, probability corresponds to a personal belief.[3] Rationality and coherence allow for substantial variation within the constraints they pose; the constraints are justified by the Dutch book argument or by the decision theory and de Finetti’s theorem.[3] The objective and subjective variants of Bayesian probability differ mainly in their interpretation and construction of the prior probability.”

Thus, we see that even the “objective” version of “Bayesianism” entails subjective cognitive evaluations – “reasonable expectations,” “rationality constraints,” “interpretation of the prior probability.”

Continuing in the Wikipedia entry, we see that, indeed, the “objective” category is the subject of much (subjective) disagreement:

“[Many theorists] have suggested several methods for constructing “objective” priors. (Unfortunately, it is not clear how to assess the relative “objectivity” of the priors proposed under these methods)…The quest for “the universal method for constructing priors” continues to attract statistical theorists.”

Given all the above, given the absence of a “universal method for constructing [objective] priors” I would say that a strong case for “Bayesian probability,” as regards its use in objective science, is still incomplete.

 Wei Wei (2018) Annual Review of Vision Science

I am puzzled by the author’s unqualified use of the term “receptive field,” a term whose meaning appears to be in flux. The simple notion that there is a circumscribed part of the retina, and a corresponding circumscribed part of perceived space, events in which affect particular neurons, has long been debunked and labelled “classical receptive field.” The understanding that the early concept was problematic came almost from the start, as indicated by the excerpt from Spillma’s (2015/JOV) article, “Beyond the classical receptive field (the two paragraphs are consecutive in the original text):

“Our perception relies on the interaction between proximal and distant points in visual space, requiring short- and long-range neural connections among neurons responding to different regions within the retinotopic map. Evidently, the classical center-surround RF can only accommodate short-range interactions; for long-range interactions, more powerful mechanisms are needed. Accordingly, the hitherto established local RF properties had to be extended to take distant global inputs into account.”

“The idea of an extended (called nonclassical or extraclassical today) RF was not new. Kuffler (1953, p. 45) already wrote, “… not only the areas from which responses can actually be set up by retinal illumination may be included in a definition of the receptive field but also all areas which show a functional connection, by an inhibitory or excitatory effect on a ganglion cell. This may well involve areas which are somewhat remote from a ganglion cell and by themselves do not set up discharges.””

The language of the above text is a bit misleading, implying as it does that the “hitherto established” local RF remained in place and merely needed elaboration. It should be clear that if the firing rate of a neuron “x” can be altered by the conditions of stimulation applying to the whole retina, then it is not possible to experimentally define a local area as in any way special based on the local conditions of stimulation. Or rather, it is artificial, privileging one set of global conditions other an infinite number of alternatives in producing a definition (which even then has not been proven to replicate). Even the verbal expansion of the term to include “non-classical receptive fields” does not rescue the concept from this problem.

The extreme confusion that the concept has produced as researchers have attempted to specify its elusive properties may be appreciated in reading Carandini et al’s (2005) “Do we know what the early visual system does?” The discussion includes reference to a black box “saving device.”

The concept of “direction-selectivity” is closely tied to the receptive field concept. It is difficult for me to understand how Wei can avoid addressing these theoretical problems.

Unqualified use of the term “receptive field” and associated concept is quite common; I’ve highlighted it in several PubPeer comments, including on El Boustani et al (2018)/Science; onBeltramo & Scanziani (2019)/Science; on Olshausen & Field (1996)/Nature

A second stab at Wei Wei also failed:

As noted in the PubPeer comment on Olshausen & Field (1996) as well as other PubPeer comments linked therein, the concept of “receptive field” is currently missing a theoretical definition. Various researchers employ different de facto definitions of the term, strictly tied to the procedures they happen to use. The use of the term by Wei in this review, without qualification or clarification, renders the discussion incomplete.

 Bakkour, Palombo, Zylberberg, Kang, Reid, Verfaellie , Shadlen , Shohamy (2019) eLife “The hippocampus supports deliberation during value-based decisions.” 

(In addition to the comment submitted to PubPeer, I note here that the authors’ use of the term “supports” is an example of Neuroscience Newspeak.)

“Bakkour et al state:

We fit a one-dimensional drift diffusion model to the choice and RT on each decision. The model assumes that choice and RT are linked by a common mechanism of evidence accumulation, which stops when a decision variable reaches one of two bounds.

I’m confused about what the authors are claiming. Experiments are based on two-alternative forced choices and structured so that the data produced may be “modelled” based on the “drift diffusion model.” The fitting procedures allow modellers quite a bit of leeway in adjusting free parameters, and many quantitative choices are unconstrained by theory. The above-stated assumptions of the “drift diffusion model”, i.e. that “choice and RT are linked by a common mechanism of evidence accumulation” are vague; no concrete description (even a vague one) in terms of neural function has ever been proposed. The drift diffusion model is an extension of “signal detection theory;” and the assumptions of this “theory” seem to lack face validity. SDT curves tend to be specific to particular experiments and not to generalize.

In short, under the circumstances I’m not sure that fitting the data acquired to the model under consideration is enough to license inferences about brain function.”

 Mueller & Weidemann (2008) Psychonomic Bulletin and Review

“SDT assumes that percepts are noisy.”

The term “percept” refers to what is consciously experienced, and generally to what is experienced visually. What we experience visually is not noisy, and does not necessitate any conscious decision-making on the viewer’s part. Conscious decision-making is, both implicitly and explicitly, what we are talking about here. Implicitly, because if the conscious perceptual experience (the percept), is noisy, then the viewer must be called on to make a conscious decision as to how to interpret it. Explicitly, because the associated experiments refer to participants’ decisions, usually binary forced-choice decisions often requiring guesses.

Given all of this, the statement that “SDT assumes percepts are noisy” is hard to interpret. The assumption seems to lack face validity, and no explanation or references, or proposals of how to test it, are offered. On what basis is the assumption considered valid?

Oberauer & Lewandowsky (2019) Psychonomic Bulletin and Review.

[It seems particularly unkind of PubPeer moderators to censor my reply to another commenter’s reply to my initial comment, which did post.]

The text you cite seems very confused and waffling to me. Which of Mayo’s arguments have you found compelling with respect to making the fruits of post hoc correlation-fishing reliable – something that, as mentioned, is virtually never the case? Has she proposed and tested a method of post hoc statistical inference that produces replicable outcomes?

Chen, Yeh & Tyler (2019) Journal of Vision

I’d like to discuss the authors’ dichotomization of the images used in their procedures into “target” and “noise.” It seems to me that this dichotomy is not a valid one, for fairly obvious reasons.

In this comment, I’ll be using the term “image” to refer to a surface reflecting light into the eyes of a seeing human.

By target, the authors are referring to certain more-or-less smoothly-changing bands of light and dark which they call “Gabors.” These patterns are typically perceived either as alternating bars or, if the transitions are fairly gradual, as partly-shaded cylinders. By “noise,” they mean a different type of pattern, consisting of variously-arranged dots.

Collections of dots always tend to be grouped spontaneously by both human and species of non-human viewers to produce various perceived shapes or patterns, among the simplest examples being the simple “rows” or “columns” of dots typically used to demonstrate principles of organization. We may see the same tendency in the grouping of stars into constellations, and the perception of objects in clouds.

Here, we have two types of patterns; one rather orderly both physically and perceptually, the other less so – but both requiring and eliciting perceptual/neural organizing processes in order for perceived structures, stable or unstable, to arise in consciousness.

When two patterns are super-imposed in an image, the structures that will emerge in consciousness are not necessarily the sum of these two. They may be – it depends on the combined pattern, and how it is interpreted by the perceptual organizing processes. The combination of the two may destroy the structural coherence of one or the other or both; and new structures may be perceived. A classic series of experiments by Gottschaldt demonstrated, many decades ago, that “targets” may not be perceived in certain contexts, even when observers expect and are actively watching for them.

It seems to me the above facts are relevant and should be addressed in the authors’ theoretical discussion.

This comment was just rejected by PubPeer. Why?

 

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