FWIW I think it's still the case that psychologists/neuroscientists are nowhere near developing an accurate lie detector. And the paper you cite doesn't seem to support the claim that lie detection technology is accurate. From the abstract (emphasis mine):

Analyzing the myriad issues related to fMRI lie detection, the article identifies the key limitations of the current neuroimaging of deception science as expert evidence and explores the problems that arise from using scientific evidence before it is proven scientifically valid and reliable. We suggest that courts continue excluding fMRI lie detection evidence until this potentially useful form of forensic science meets the scientific standards currently required for adoption of a medical test or device.
 

There are methodological challenges associated with the typical studies done on lie detection. From a 2016 paper (emphasis mine):

Great hopes and expectations were expressed regarding the potential use of brain imaging techniques for the detection of deception. Contrary to what has been advocated by many researchers as well as practitioners (e.g., Bles & Haynes, 2008; Farwell, 2012; Langleben et al., 2005), the introduction of new measures such as P300 and fMRI is by no means a solution to the problems associated with the ANS-based CQT polygraph test. The CQT has been criticized for lacking proper controls and being unstandardized. In addition, its outcome is often contaminated by prior information available to the examiner. None of these criticisms can be resolved by replacing ANS recordings with fMRI measures.

Moreover, all paradigms face a similar logical problem: deception cannot be directly inferred either from the presence of emotional arousal in the CQT or from attentional orienting or inhibition in the CIT or DoD, regardless of whether ANS, reaction times, ERPs, or fMRI measures have been used.

So I'm not sure what the basis is for saying it's an "unambiguous mistake" to think accurate lie detection technology is a long way off.

I'm personally skeptical that we'll ever "solve" what the neural basis of sentience is. That said, I think there are still some promising ways a better understanding of psychology can advance standard EA causes. Here's a paper that goes into more depth on this issue:
https://pubmed.ncbi.nlm.nih.gov/35981321/

But for the paradox's setup to make sense, the player must have, in some sense, made his decision before the prediction is made: he is either someone who is going to take both boxes or someone who is just going to take the opaque box.

This doesn't seem correct. It's possible to make a better than random guess about what a person will decide in the future, even if the person has not yet made their decision.

This is not mysterious in ordinary contexts. I can make a plan to meet with a friend and justifiably have very high confidence that they'll show up at the agreed time. But that doesn't preclude that they might in fact choose to cancel at the last minute.

I suppose I agree that humanity should generally focus more on catastrophic (non-existential) risks.

That said, I think this is often stated explicitly. For example, MacAskill in his recently book explicitly says that many of the actions we take to reduce x-risks will also look good even for people with shorter-term priorities.

Do you have any quote from someone who says we shouldn't care about catastrophic risks at all?

Maybe a more realistic example would be helpful here. There have been recent reports claiming that, although it will negatively affect millions of people, climate change is unlikely to be an existential risk. Suppose that's true. Do you think EAs should devote as much time and effort preventing climate change-level risks as they do preventing existential risks?

I found this post insightful! Although it's a brief post, I'd recommend providing a brief heading for each section for people who are heavy skimmers.

I'm not sure I understand your point then...

Surely a future in which humanity flourishes into the longterm future is a better one than a future where people are living as "ants." And if we have uncertainty about which path we're on and there are plausible reasons to think we're on the ant path, it can be worthwhile to figure that out so we can shift in a better direction.

For example: Does it make any difference whether a non-alligned superintelligent AGI will actively try to kill all humanity or not? If we are certain that it won't, we would still live in a world where we are the ants and it is humanity.

This misunderstands what an existential risk is, at least as used by the philosophers who've written about this. Nick Bostrom, for example, notes that the extinction of humanity is not the only thing that counts as an extinction risk.  (The term "existential risk" is unfortunately a misnomer in this regard.) Something that drastically curtails the future potential of humanity would also count.

I have no idea, I've spent less than a half hour looking into this. The Cochrane Review shows that there's maaaybe an advantage to water flossing, but there just haven't been that many studies on it. And the studies do assume that participants are  flossing/water flossing at the same frequency. If the pleasant sensation you get from water flossing motivates you to keep doing it, I think that's great!

I like this list!

Just a heads up for the studies about water flossing:

Two of them were  funded by WaterPik and another is published in the "Journal of Baghdad College of Dentistry," which looks... suspicious from my naive perspective.

A recent Cochrane Review compares toothbrushing against tooth brushing + water flossing (aka "oral irrigating"):

Very-low certainty evidence suggested oral irrigators may reduce gingivitis measured by GI at one month (SMD -0.48, 95% CI -0.89 to -0.06; 4 trials, 380 participants), but not at three or six months. Low-certainty evidence suggested that oral irrigators did not reduce bleeding sites at one month (MD -0.00, 95% CI -0.07 to 0.06; 2 trials, 126 participants) or three months, or plaque at one month (SMD -0.16, 95% CI -0.41 to 0.10; 3 trials, 235 participants), three months or six months, more than toothbrushing alone.

It also compares water flossing with regular flossing:

Low- to very low-certainty evidence suggested oral irrigation may reduce gingivitis at one month compared to flossing, but very low-certainty evidence did not suggest a difference between devices for plaque.