
Bayesian analysis of ego-depletion studies favours null hypothesis - mkempe
http://onlinelibrary.wiley.com/doi/10.1111/bjso.12236/full
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danschumann
According to marines, will power depletion is bs. This is anecdotal, sure, but
I believe in momentum. If you have momentum, at some point, you don't want to
fail at any will power task, because you are on a winning streak.

~~~
travjones
Interesting. There is actually a concept from behavior analysis called
"behavioral momentum." [1]

1:
[https://en.wikipedia.org/wiki/Behavioral_momentum](https://en.wikipedia.org/wiki/Behavioral_momentum)

~~~
dwaltrip
Reminds me of how the hardest part of many tasks is simply getting started.

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closed
I'll have to look more closely at the paper, but am very surprised by this
result! I've always figured the effect sizes were quite small, and there are
good researchers who don't buy its main explanations, but the idea of ego
depletion shows up in a lot of areas under different names (e.g. "resource
depletion in working memory").

Pretty contentious area of research, so I'm sure this will be some nice fuel
for the fire..

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nurettin
Not disputing the paper or the scientific method applied here, but how is
"bayesian factor" different than p-values?

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tmalsburg2
In a nutshell: If the p-value is below some conventional threshold (in
psychology it's usually 0.05), you can conclude that the null-hypothesis (no
effect) is likely wrong and that something else must be the case. However, if
p is above the threshold you can't conclude anything, because that means that
there is either no effect or that the data was not sufficient to show the
effect. So the p-value method (formally known as null-hypothesis significance
testing, NHST) can only ever be used to reject the null hypothesis but not to
support it. This is where Bayes factors are different. In that approach, you
formulate not just one hypothesis but two. Then you test how well both
hypotheses are supported by the data. Three conclusions are possible:
Hypothesis A receives more support, the alternative hypothesis receives more
support, there is not enough evidence to conclude anything with sufficient
certainty. Presented this way, the Bayes factor approach appears to be
strictly superior to NHST. But there are also some complications that make
Bayes factors tricky (related to how you select and formulate the hypotheses)
and some statisticians go as far as to say that Bayes factors are obviously
non-sense (e.g. Andrew Gelman). The truth is probably that they are neither a
panacea nor non-sense.

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nurettin
That makes a lot of sense, but can't you model two null hypotheses using the
same data in some clever way?

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tw1010
It feels like the fact that this is a bayesian-favoured study is some kind of
sign that people (i.e. people that are upvoting, not necessarily the
researchers) are actually taking that silly bayesian vs frequentist political
war thing seriously. (Which I don't think is advisable.)

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nonbel
I agree, there is no reason to mention "bayesian" in the title other than
using it as a hype term like "blockchain" or "deep learning".

Also, the real difference is whether they test a "null hypothesis" vs testing
an "actual hypothesis". Like almost all psych, this falls in the first
category.

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KirinDave
You say this but then you go read a paper with a cruddy t-test and then injure
your eyes with the spasmodic rolling that it induces, like I did.

It's kinda remarkable how many people don't actually use modern bayesian
analysis techniques, which is why it's such a policy war. It's the difference
between "older statistical methods uninformed by the glut of modern processing
power" and "things which require a computer to do well, and preserve
uncertainty."

~~~
closed
I don't think it's an issue of old versus new methods. Daniel Lakens has an
great string of blog posts / publications on how a lot of the same things can
go wrong with Bayesian anaylses [1], and how p-values can be viewed as a "poor
man's Bayesian updating function" [2].

[1]: [http://daniellakens.blogspot.com/2017/03/no-p-values-are-
not...](http://daniellakens.blogspot.com/2017/03/no-p-values-are-not-to-blame-
part-53.html)

[2]: [https://daniellakens.blogspot.com/2015/11/the-relation-
betwe...](https://daniellakens.blogspot.com/2015/11/the-relation-between-p-
values-and.html)

~~~
KirinDave
When I do not have a processor easily capable of bayesian mkmv sampling I'll
consider using that method.

But I do and I guess this means I am rich? Sure.

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colemannugent
I always get the feeling from reading academic material on psychology that
people are trying to apply the scientific method on top of unscientific
principles. It feels rather like alchemists trying to explain fire via
phlogiston: an attempt to quantify high-level phenomena when you don't
understand any of the lower levels.

All the data comes from psychology students at a college in the US who either
were able to use their participation for a course requirement or given extra
credit. The method by which they generated and measured depletion seems
adequate, but all the data is self reported based on how the test subjects
felt.

The statistics gives evidence linking the amount of generated depletion and
the reported depletion, but not any insight into what mechanism actually
causes depletion. What use is this? Why build a map when we cannot effectively
observe the territory?

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z55
It might not seem as clear cut as other natural sciences (which also get fuzzy
once you go into the details) but there is credibility in psychological
reasoning. The mechanisms that cause a certain behavior are represented as
models in psychological research. Such models must, by design, simplify the
real mechanisms. But, as opposed to the real mechanism, they can be discussed
and disproven, which is what apparently happened here.

~~~
colemannugent
> _It might not seem as clear cut as other natural sciences (which also get
> fuzzy once you go into the details) but there is credibility in
> psychological reasoning._

Any "fuzziness" in the other natural sciences (thinking biology, chemistry,
physics, astronomy, etc.) is usually limited by current technology or
measurement methods. Newton's classical mechanics were observably true for a
long time before their flaws started showing. In most situations, classical
mechanics is all you need to accurately model a system. Is there any such well
accepted theory that semi-accurately predicts psychological phenomena in a
similar fashion?

I agree that sometimes psychological findings seem credible because they align
with our personal models of how we think people work, but this gives you
nothing in terms of the scientific method. Just because a model is intuitive
doesn't mean that it is any more true.

> _Such models must, by design, simplify the real mechanisms._

What model? They essentially have a single claim backed by evidence. I don't
see what predictive power their conclusion brings. We don't understand what
"ego-depletion" is, how can we pretend to measure it? How can this
"measurement" of something that we don't understand give us any more
information about human psychology?

What real mechanism have they suggested as an explanation for this phenomenon?
I didn't see one.

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piratebroadcast
ELI5?

~~~
colemannugent
Basically, there was a theory that exercising self-control would "deplete"
ones "self-control reserves". The idea was that exercising your self-control,
to say avoid a junk food, would temporarily decrease your ability to resist
that temptation again.

This paper reports that not only were they unable to verify any of the prior
research into this so called "ego depletion" effect, but they found more
persuasive evidence suggesting that the theory is false.

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krashidov
This is reassuring. Every time someone told me this I figured it had to be
bullshit. I think people used it as an excuse to make bad decisions.

~~~
mizzao
...and you're exemplifying confirmation bias right there, which is the whole
reason this happened in the first place.

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inimino
Having an opinion that is later vindicated is not the same thing as
confirmation bias.

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dbecker
It's disappointing to see links to the abstracts on the front page of HN
(given the paper itself is behind a paywall).

In this case, the find some non-zero effect, but call it zero because the
difference was not statistically significant.

That's likely a reflection of their small sample size rather than evidence for
the null hypothesis as the title suggests.

But it's hard to know, or even have an intelligent discussion about it, since
the paper itself is behind a paywall.

~~~
shaki-dora
Sample size is, of course, one of the factors included in any analysis that
gives you a p-value, or any other measure of confidence.

In this case, the abstract specifically mentions a "Bayes factor > 25". The
Bayes Factor is the likelihood, i. e. the ratio of probabilities for two
competing hypotheses. With no information whatsoever, it is 1. A factor of 25
means that the null hypothesis is 25 times as likely to be correct as the
theory of ego depletion.

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meesterdude
I'm all for replication and ensuring scientific accuracy - but this does not
change my perspective of ego-depletion.

I have observed it in myself, time and time again. If not it directly,
something similar enough. Even at a glucose level, various studies have shown
relation between our blood sugar and ability to tolerate frustration and make
decisions.

So while the accuracy of ego-depletion may be in question, I can still benefit
from reasoning it to be true and challenging my emotions and expectations with
that. if/when a better model or perspective comes around i'll surely adopt it.

But of course, if this news in some way helpful or freeing for you, by all
means ride that wave. Success matters more than truth.

I've observed that psychology will sometimes split hairs - arguing over whats
true and whats truer. Overall this is good - but it's helpful to consider the
proliferation of blatant non-truths out there and how far we've come.
Sometimes "good enough" is good enough. Fill in the blanks with the facts you
can find today and be willing to swap them out for better ones tomorrow.

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BeetleB
>Even at a glucose level, various studies have shown relation between our
blood sugar and ability to tolerate frustration and make decisions.

I think it is exactly these kinds of studies that are being questioned. Can
they be reproduced?

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watwut
Stay hungry (e.g. On low calorie diet) for few days and then watch yourself
more nerveus and making dumber decisions.

~~~
fpoling
I fasted for few days on many occasions. The only ill effect was that it was
difficult to fall asleep and the sleep was very shallow on second and third
night. After that sleep got better. I have not noticed any dumbness.
Subjectively perception even improves. This is in line with experience I read
in books and articles.

Sometime I use that if I need to drive a long way. I stop eating the day
before that ensures that I never fall asleep behind the wheel and my attention
stays sharp all the time.

