Unwilling or unable? Interpreting effort task performance in myalgic encephalomyelitis/chronic fatigue syndrome, 2025, Kirvin-Quamme et al

[Wyva]

Andrew Kirvin-Quamme, Karen D. Kirke, Oscar Junge, Jonathan C. W. Edwards, Kevin J. Holmes

Introduction

In a recent, high-profile study of post-infectious myalgic encephalomyelitis/chronic fatigue syndrome (PI-ME/CFS), Walitt et al. (2024) assessed the performance of patients and healthy volunteers on the Effort-Expenditure for Rewards Task (EEfRT), among a host of other measures. The EEfRT is a widely used behavioral index of reward motivation and effort-based decision-making that requires repeatedly choosing between an easy task and a hard task, each involving rapid, repetitive button-pressing (Treadway et al., 2009). Walitt et al.'s study—the first to investigate effort-based decision-making in PI-ME/CFS—found that patients were less likely to choose the hard task than healthy volunteers. The authors interpreted this difference as evidence of altered “effort preference,” which they defined as “how much effort a person subjectively wants to exert” (p. 9). Walitt et al. concluded that “effort preference, not fatigue, is the defining motor behavior of this illness” (p. 10). Here we interrogate this conclusion. Were PI-ME/CFS patients less likely to choose the hard task because they wanted to exert less effort, consciously or otherwise? Or were they less able to complete the hard task, and thus chose it less often? We argue that the data support the latter interpretation.

Open access: https://www.frontiersin.org/journals/psychology/articles/10.3389/fpsyg.2025.1593269/full

 

[Andy]

"Acknowledgments

Several ME/CFS patients from the Science4ME community, who wish to remain anonymous, contributed to the conceptualization of this project. The authors, some of whom are ME/CFS patients themselves, are grateful for their valuable insights."

 

[ME/CFS Skeptic]

Great work, thanks to all authors!

 

[Braganca]

Great job, huge thanks to the authors and the anonymous contributors!

 

[Peter T]

An important and well written rebuttal to an ill thought through research paper that is potentially harmful to people with ME/CFS.

 

[rvallee]

For the EEfRT to yield interpretable results, participants' choices between the easy and hard tasks must be decoupled from their ability to complete these tasks. As the developers of the measure cautioned, “an important requirement for the EEfRT is that it measure individual differences in motivation for rewards, rather than individual differences in ability or fatigue”

I will never understand how this isn't the end of it. The paper could simply be that and it should be enough to kill the whole thing. Medicine is in such a dysfunctional state that nothing seems to get in the way of getting fake results.

When some forum users contacted the developer of this test, he had no issues with this. Something he's written as a strict requirement, but he doesn't even care about that. Presumably because he doesn't think it applies here, based on whatever opinion of ME/CFS he may have. An opinion, which he is wrong about, showing how even strict requirements don't matter, because they are simply matters of arbitrary opinion.

And that doesn't even take into account that this test is not reliable about anything. Or how the concept of "effort preference" is pure nonsense. It's so freaking arbitrary.

This is not science. It has nothing to do with science. Phrenology was more scientific than this, because at least the measurements were objective, and they were actual measurements, not ratings, or scores, or biased questionnaires. Their interpretation was pure nonsense, but it's still more scientific than this mess. Textbook pseudoscience is more serious than this mess. And this mess came out a couple of years ago. Freaking hell.

In a sane world, with sane, competent professionals involved, this would matter:

The amount of effort a person wants to exert on a task is irrelevant if they are unable to exert it.

But it does not matter. Because we are not a sane species.

 

[forestglip]

When some forum users contacted the developer of this test, he had no issues with this. Something he's written as a strict requirement, but he doesn't even care about that.

That's interesting. Is this correspondence on the forum somewhere?

 

[NelliePledge]

Top debunking

 

[Trish]

Excellent work. Really well argued and clearly written.

I think it's sufficient clear evidence for Wallitt et al to be asked to retract their original paper. Is there any move in that direction? Has Walitt been contacted for a response?

I wonder if this is an error - should it be 'no financial support.'?

Funding​

The author(s) declare that financial support was received for the research and/or publication of this article. The publication fee was supported by a start-up award from Reed College to KH.

 

[Utsikt]

I wonder if this is an error - should it be 'no financial support.'?

They received financial support for the publication, it I understood the last sentence correctly.

 

[Trish]

Ah, OK, I misunderstood the first sentence as a separate statement. Reading again, it's clear it refers to the second sentence.

 

[ME/CFS Skeptic]

That's interesting. Is this correspondence on the forum somewhere?

Discussed here:

Post in thread 'Use of EEfRT in the NIH study: Deep phenotyping of PI-ME/CFS, 2024, Walitt et al'

Mar 5, 2024

Got a reply from Treadway on EEfRT. He seems suitably cautious about the utility of using it in this population.

Hi,

Sorry for the delay. The task has not been specifically validated as a measure of fatigue. My understanding of the paper is that they are trying to understand the clinical features of this illness, which are not well known. In that sense, it seems appropriate to me to use the EEfRT as an exploratory measure to determine whether it is sensitive to PI-ME. In other words, I would look at this study as an initial attempt in the validation of the EEfRT for this type of...

• Murph

• 

 

[Utsikt]

Discussed here:

Post in thread 'Use of EEfRT in the NIH study: Deep phenotyping of PI-ME/CFS, 2024, Walitt et al'

Mar 5, 2024

Got a reply from Treadway on EEfRT. He seems suitably cautious about the utility of using it in this population.

Hi,

Sorry for the delay. The task has not been specifically validated as a measure of fatigue. My understanding of the paper is that they are trying to understand the clinical features of this illness, which are not well known. In that sense, it seems appropriate to me to use the EEfRT as an exploratory measure to determine whether it is sensitive to PI-ME. In other words, I would look at this study as an initial attempt in the validation of the EEfRT for this type of...

• Murph

• 

So, they completely ignored the explicit assumptions that have to be fulfilled for their own test to be valid? Even a first year economics student would be failed if they tried to use a model that way on an exam.

 

[Peter T]

Discussed here:

Post in thread 'Use of EEfRT in the NIH study: Deep phenotyping of PI-ME/CFS, 2024, Walitt et al'

Mar 5, 2024

Got a reply from Treadway on EEfRT. He seems suitably cautious about the utility of using it in this population.

Hi,

Sorry for the delay. The task has not been specifically validated as a measure of fatigue. My understanding of the paper is that they are trying to understand the clinical features of this illness, which are not well known. In that sense, it seems appropriate to me to use the EEfRT as an exploratory measure to determine whether it is sensitive to PI-ME. In other words, I would look at this study as an initial attempt in the validation of the EEfRT for this type of...

• Murph

• 

If the study was using the research to validate the use of this test with people with ME/CFS shouldn’t they have been up front about doing that pointing out that it may not be relevant to use it in the way they did and then giving a justification of why their research had validated its use if that was what the believed, rather than just reporting it as though there was no need to validate it in the first place.

 

[jnmaciuch]

Great succinct argument by the authors, thank you for your work!

 

[Karen Kirke]

Thanks everyone. We worked really hard on this for a long time. So we are delighted that it has now been published.

This was a really fun collaboration, which was just as well, as we ended up having to do so much work together. I would work with @andrewkq, @OscarJunge, @Jonathan Edwards and Kevin Holmes again in a heartbeat. Particular thanks to Kevin for ensuring that a publication fee did not stand in the way of a patient-scientist collaboration seeing the light of day.

@andrewkq shared this post on the EEfRT and Deep Phenotyping threads, which will hopefully be seen by people who were there when our argument was born:

Hi everyone, it’s been some time since I last posted, but I’m very excited to share that our critique of Walitt et al.’s effort preference claims was finally published today! The article is titled Unwilling or unable? Interpreting effort task performance in myalgic encephalomyelitis/chronic fatigue syndrome and can be found at the following link: https://www.frontiersin.org/articles/10.3389/fpsyg.2025.1593269

A dedicated S4ME thread for discussion is already underway: https://s4me.info/threads/unwilling...igue-syndrome-2025-kirvin-quamme-et-al.44601/

This article wouldn’t have come together without this community—thank you to everyone who contributed, and especially to my co-authors. It’s been quite a journey to get it published. I hope to post more soon about what went on behind the scenes, but in the meantime, we’re happy to answer any questions about the process and decisions made along the way.

Please share the article with your networks and let us know what you think!

@Simon M , you see those mean lines on the figure? I suggested we add those to Andrew's figure because of you! And we all liked them. I hope they do what you like mean/median lines to do.

I'm looking forward to a day when people who are incapacitated by ME/CFS get effective treatment, rather than having to expend their meagre energy on refuting arguments like this.

 

[Jonathan Edwards]

Just to ensure credit goes where it's due. I offered to co-author to provide whatever contextual advice /support I might have available. It rapidly became clear that the others understood far more about everything than I did and all I could do was enjoy the skill of the analysis and the clarity of the presentation.

An honor to be included.

 

[hibiscuswahine]

Thanks to the authors and all members here who contributed to the debunking initially and in this excellent paper.

So grateful we have people like you giving such reasoned and scientific arguments against these researchers.

 

[rvallee]

So, they completely ignored the explicit assumptions that have to be fulfilled for their own test to be valid? Even a first year economics student would be failed if they tried to use a model that way on an exam.

I can't see any other explanation, for the creator of the test or for Walitt and Nath, that they just don't believe we have any such limitations.

Even though we clearly do, as this paper shows. The test creator may have some excuse for it, but Walitt and Nath sure as hell don't. They sort of argued it based on tests of grip strength being close enough, or something like it, but it fundamentally misses the point about PEM.

So in their minds they respect those criteria. Which makes it clear that those criteria are pretty much useless, as they can simply be arbitrarily argued away based on nothing but beliefs, or lack thereof. Which is not surprising in the case of psychosomatic beliefs, where there is an overarching belief in their ability to judge whether someone is behaving in excess of how they should.

 

[Hutan]

A very nice, tightly argued paper.

Looking at that excellent Figure 1, it's rather clear that there really wasn't that much of a difference between proportions of hard task choice anyway (the y axis). Most participants are choosing the hard task between 20 and 50% of the time. The regression line is pretty flat - the proportion of completed tasks does not have much effect on the proportion of hard task choices. If you exclude the 2 or at best 3 healthy volunteers who chose the hard task relatively often, there is not much difference between the 'healthy volunteers* and the 'ME/CFS patients* in terms of proportion of hard task choices.

If most of the healthy people look like most of the ME/CFS people in terms of proportion of hard tasks selected, then the measure doesn't have much discriminatory power, and probably isn't telling us much about ME/CFS.

Then, there was that healthy control who was excluded from the study because he was supposedly gaming the system - which was rather ironic given the task was supposedly about making choices to maximise the reward. If I recall correctly (and I may well not be), the reward system was set up so that the best strategy was to complete a few tasks with high reward and fail to complete the rest, maximising the chance that a high reward task would be randomly selected for payout from the completed tasks. I think the exclusion of that person who followed a reward maximising strategy changed the overall finding towards what Walitt wanted to find?

If I'm recalling that situation correctly, it is possible that some of the ME/CFS participants were following a 'work smarter, not harder' strategy, somewhat similar to what the excluded healthy control was. The two healthy controls with higher rates of hard task selection had perhaps failed to understand the implications of the reward scheme, instead being focussed on demonstrating how healthy and physically superior they were.

I can't recall now, but I think there may have also been some issues with the two cohorts in the effort preference test not being well matched on age and sex? Even without any complications arising from those possible differences, the experiment was an uninterpretable mess. The reduced physical capacity of some of the ME/CFS participants, deliberate strategising favouring low rates of completion, and the possible motivations of the healthy controls to demonstrate physical prowess all possibly affecting what people did in this very small study in ways that are rather hard to unravel at this point.

These are just comments fired off on the basis of vaguely remembered facts - so I'm very happy for the authors or others to tell me about things I have got wrong.


* Just by the way, NIH (Mr Walitt), all of the participants were volunteers and the people with ME/CFS were not receiving medical care, so weren't really patients. Referring to the controls as 'healthy volunteers' and the people with ME/CFS as 'ME/CFS patients' could be seen as a subtle refusal to honour the effort the substantial effort people with ME/CFS were making to be in the Intramural Study.