Seems like a case of Simpson’s Paradox https://en.wikipedia.org/wiki/Simpson%27s_paradox
Not to be confused with Flanderization.
Group averages obscure how an individual's brain controls behavior: study
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Re: Group averages obscure how an individual's brain controls behavior: study
#12The specific counterintuitive result is mentioned toward the end of the article, and I'm having some trouble understanding it: > when analyzing average trends in groups of children, slower reaction times to the “Go” signal were linked to increased activity in many brain regions, including the default mode network > However, when an individual had a slower reaction time to the “Go” signal, activity decreased in the de…
Acting on your first impulse is fast (default mode).
Denying that first impulse, thinking about it, and then acting is slow.
Re: Group averages obscure how an individual's brain controls behavior: study
#13Yup, to no one’s surprise (least of all the investigators), doing neuroscience by correlating cortex regions with cognitive activities is extremely clunky at best. Very robust finding confirming this tho, thanks for sharing!
Now that we’re finally moving to the next stage of neuroscience due inscrutable latent systems (aka LLMs), I can’t help but feel some nostalgia. It’s all fun and games until someone makes a lie detection helmet that actually works…
Re: Group averages obscure how an individual's brain controls behavior: study
#14"This approach was also able to identify subgroups of children with different levels of cognitive control and performance monitoring, or the ability to modify one’s strategy after making an error." This should surprise no one. You took a large population and found subpopulations within it. If you want to look at a population average, then use the population data. If you want to look at kids with specific attention ne…
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Medical professionals have a history of not necessarily having complete understanding of the maths they use in their work. Classic example of a nutritionist 'inventing' the trapezoid rule for calculating area under a curve, and then naming it after herself. And then many many other medical people unironically using said method and citing her.
Re: Group averages obscure how an individual's brain controls behavior: study
#15While interesting, I get a few questions from this:
- As another commenter said, this is a known disadvantage of averages. I'm curious if it's possible to get a median result from per-individual averages. I'm not familiar enough with how this research is done to get a result.
- Was any effort made to re-test individuals in a second/third/etc session, showing consistent patterns to the brain activity? I know it was consistent within a session, but I'm curious if it might change week over week.
Re: Group averages obscure how an individual's brain controls behavior: study
#16"This approach was also able to identify subgroups of children with different levels of cognitive control and performance monitoring, or the ability to modify one’s strategy after making an error." This should surprise no one. You took a large population and found subpopulations within it. If you want to look at a population average, then use the population data. If you want to look at kids with specific attention ne…
The point isn’t that they found subgroups, the point is the method they used to find them — namely, analyzing individual brain scans rather than averaging them out first.
Re: Group averages obscure how an individual's brain controls behavior: study
#17Is this common sense and by definition of what an average is?
In a sense, but it is a bit more devious. It basically invalidates all past fMRI studies. Not that anyone should have taken those seriously, but it looks like another nail in the coffin. fMRI analysis is (was?) basically: squeeze each brain scan into a standard box, then average the BOLD responses (that's roughly oxygen usage between 3s and 9s after activity). This abstract says that --at least in some cases-- those…
What cases was it saying it was lying? An average and a median can be drastically different without the average being false, right?
Re: Group averages obscure how an individual's brain controls behavior: study
#18Earlier quoted context omitted.
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Medical professionals have a history of not necessarily having complete understanding of the maths they use in their work. Classic example of a nutritionist 'inventing' the trapezoid rule for calculating area under a curve, and then naming it after herself. And then many many other medical people unironically using said method and citing her. https://en.wikipedia.org/wiki/Tai%27s_model
A) these aren’t “medical people”, they’re neuroscientists and psychologists. Comparing them to a nutritionist seems especially cruel!
B) “some people have been wrong before” is not a reason to think you know better than the authors of an upcoming Nature article based on a few layperson-targeted paragraphs summarizing the paper from a very high level.
Re: Group averages obscure how an individual's brain controls behavior: study
#19"This approach was also able to identify subgroups of children with different levels of cognitive control and performance monitoring, or the ability to modify one’s strategy after making an error." This should surprise no one. You took a large population and found subpopulations within it. If you want to look at a population average, then use the population data. If you want to look at kids with specific attention ne…
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That seems awfully like an appeal to authority. Your parent comment doesn't just vaguely snipe, but points out reasons this should have been expected. Those reasons could potentially not be valid, or not present the whole picture, but "the researchers are from Stanford" doesn't rebut them.
Re: Group averages obscure how an individual's brain controls behavior: study
#20Earlier quoted context omitted.
Medical professionals have a history of not necessarily having complete understanding of the maths they use in their work. Classic example of a nutritionist 'inventing' the trapezoid rule for calculating area under a curve, and then naming it after herself. And then many many other medical people unironically using said method and citing her. https://en.wikipedia.org/wiki/Tai%27s_model
A) these aren’t “medical people”, they’re neuroscientists and psychologists. Comparing them to a nutritionist seems especially cruel! B) “some people have been wrong before” is not a reason to think you know better than the authors of an upcoming Nature article based on a few layperson-targeted paragraphs summarizing the paper from a very high level.
> “some people have been wrong before” is not a reason to think you know better than the authors of an upcoming Nature article based on a few layperson-targeted paragraphs summarizing the paper from a very high level.
Nor is "this paper is going to appear in Nature" a reason not to wonder whether there might be something that the authors don't know. The whole point of science is that anyone can make an informed critique and self-evaluation of it, with no necessity of depending on a priesthood to interpret it. You can point out the flaws in giantg2's argument https://news.ycombinator.com/item?id=47995899, but neither the venue of the paper, nor the fact that the argument is directed at laypeople in a forum frequented by laypeople, seems to me inherently to indicate such flaws.