Confirmation Bias Masks Truth OR Confirmation Bias, Masks, Truth

30 Jun

Confirmation bias – the tendency to process information by looking for, or interpreting, information that is consistent with one’s existing beliefs. (Source: Britannica)

It shouldn’t matter what your political affiliation is when it comes to face masks. This is not about if we should go into lock down or not. It’s not about freedom (because there are lots of things we can’t do in a free country). This is simply about 1 question. Will wearing a face mask mitigate transmission of a dangerous disease that is killing a tremendous number of people?

If you’re not following the primary sources of information, like journals or medical news sites like STAT News, you might think that there’s divided science on this. But that’s simply not accurate. I have a running page on studies that have looked specifically at face mask use and COVID-19 that I’m keeping updated as new papers come out. As I note there, overwhelmingly these studies show how masks can help.

Some key reasons why people think the science is divided are simply because of the news sources they watch, the echo chamber they live in and confirmation bias. A person can avoid this by following non-biased news, really listening to and reading (not just passing over) the other side, and avoiding confirmation bias (which also just contributes to that misinformed echo chamber).

For example, the WHO changed their position on masks on June 5, and now advocate for usage of face masks by the general public. Yet, people still ignorantly write that the WHO opposes face masks on their social media posts. (I saw two today, June 30.) This clearly shows how people share things due to confirmation bias, and that they don’t even bother to look up facts. And it’s not just this. People continue to share old clips about Fauci, bogus posts about OSHA, old news articles, etc. All of these contain out of date or false information, yet it fits their bias, so without any research, they share it, and shout, “SEE!”

I want to illustrate a perfect example of this going on right now. I’ve seen this post shared recently many times by people who argue against masks. Masks Don’t Work: A Review of Science Relevant to COVID-19 Social Policy by Denis G. Rancourt.

I would bet that not a single person who I saw that shared it bothered to read even one of the studies (beyond perhaps looking at the abstract). Because I did, and what I found did not even remotely support Rancourt’s argument. In fact, one of the studies essentially says the opposite! So I encourage you to check them out, but if you’re interested in a quick overview, here’s what I found.

Rancourt’s claims are that “masks don’t work” and several studies “anchor” the “extensive scientific literature that establishes that wearing surgical masks and respirators (e.g., “N95”) does not reduce the risk of contracting a verified illness” all in the context of COVID-19 social policy.

So, is he right and are these studies relevant to COVID-19?

Jacobs, J. L. et al. (2009) “Use of surgical face masks to reduce the incidence of the common cold among health care workers in Japan: A randomized controlled trial”
Rancourt’s comment on this paper is, “N95-masked health-care workers (HCW) were significantly more likely to experience headaches. Face mask use in HCW was not demonstrated to provide benefit in terms of cold symptoms or getting colds.”
My review: The study only has an “n” of 24, so that’s not very convincing, a fact acknowledged by the authors if someone reads the paper and not just the abstract. And yes, the mask group experienced more headaches (29% v. 9%), but come on, if you wear an N95 tightly for 12 hours, I’m not surprised some people might have a headache from a mask compressed against their face and bands around their head. But this is nothing like being asked to wear a surgical mask when you go in the grocery story. But more importantly, this study doesn’t even measure the more relevant metric for COVID-19, namely if viral transmission can be reduced FROM someone wearing a mask. Rather, it only measures if viral transmission was reduced TO someone. That’s not the main reason the public is being asked to wear masks. Also, this study, unlike so many of the recent studies, doesn’t have info on COVID-19, because it wasn’t around then. The SARS-CoV-2 virus is different. So, how is this study even really relevant to the crisis today?

Cowling, B. et al. (2010) “Face masks to prevent transmission of influenza virus: A systematic review.”
Rancourt writes on this review, “None of the studies reviewed showed a benefit from wearing a mask, in either HCW or community members in households (H). See summary Tables 1 and 2 therein.”
My review: First off, this study is looking at influenza, a completely different virus, with a vastly different R0, so note that again, we’re not really comparing apples to apples here. But his statement is not really consistent with the content of the paper. While the authors state there’s not a lot of data to support the prevention of a person being infected, they do acknowledge there is a little, and indicate that the current body of information isn’t really conclusive. Hardly “none show a benefit”. And remember, that’s the transfer TO part only there. Importantly, these authors also looked at the transfer FROM aspect and they noted that there IS some evidence to “support the wearing of masks or respirators during illness to protect others”. This is clearly in favor of the “yes, wear a mask” position and goes against his view. Rancourt left that reference out. It’s like he’s counting on people not looking these up.

bin-Reza et al. (2012) “The use of masks and respirators to prevent transmission of influenza: a systematic review of the scientific evidence.”
Rancourt only offers a quote from the paper, “There were 17 eligible studies. … None of the studies established a conclusive relationship between mask/respirator use and protection against influenza infection.”
My review: Like the study above, this one primarily looked at influenza, different R0, different transmission mode significance. Yes, there were 17 studies about influenza looked at, and there was not conclusive benefits found with that virus. Still, the authors did note they found, “evidence of reduced rates of influenza-like illness if household contacts consistently wore the mask or respirator.” So, wearing a mask properly may help protect someone from getting influenza in certain circumstances. (But again remember this is only the TO part of the equation.) However, the most important thing to report about this study, BY FAR, is that the researchers here also looked at SARS-CoV-1 (a virus much more similar to SARS-CoV-2, the cause of COVID-19). They specifically state, “SARS is an unusual acute viral respiratory infection with a very different epidemiology to almost all other respiratory viral infections. It is fundamentally different from human influenza.”  Rancourt conveniently leaves that part out. Furthermore, in the paper the authors note that 8 of the 9 studies they looked at on SARS, “found that mask and ⁄or respirator use was independently associated with a reduced risk of severe acute respiratory syndrome.” In other words, masks worked for SARS! The fact that Rancourt left this out is ridiculous and shows that he is selectively mining quotes to meet an agenda. This is not science. It’s politics! 

Smith, J.D. et al. (2016) “Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis.”
Rancourt only offers a quote from this paper, “We identified six clinical studies … . In the meta-analysis of the clinical studies, we found no significant difference between N95 respirators and surgical masks in associated risk of (a) laboratory-confirmed respiratory infection, (b) influenza-like illness, or (c) reported work-place absenteeism.”.
My review: How is this helping his case? This study doesn’t even look at infection rate baseline. It’s just a comparison of one type of mask to another that showed that there wasn’t much difference. It was a waste of time to read this paper in the context of facemask use and the general public for COVID-19 mitigation. Why did he even include it? Perhaps because he’s counting on your confirmation bias.

It sure is ironic that the people calling others sheep are actually the ones that are following their media source like sheep, without bothering to look up the facts.

2 Responses to “Confirmation Bias Masks Truth OR Confirmation Bias, Masks, Truth”

  1. Kyle July 20, 2020 at 10:47 am #

    I’m preparing to do a live debate with Rancourt on this, and this was very helpful. Thank you.

    In case you are unaware, there is another article trying to “pull the same thing.”

    I started to debunk it here

    … but If you have time, a review of what the all studies it cites actually say would be very useful.

    • disciple July 20, 2020 at 12:34 pm #

      Kyle, thanks for the note.

      I reviewed the article from Ms. Huber. One thing I found odd was how she listed her references. She makes it look like there are so many (42), but in fact several of them are repeated and she doesn’t use proper citations to note this. On a quick glance, I saw at least 5 of these. That seems a bit deceptive.

      I thought your responses to her first two references were spot on, as well as pointing out that the authors of #22 and #29 clearly don’t agree with the way she is using their work.

      As for the others, I reviewed #5, #6 and #7 in this post.

      She cites the same study three times in #11, #27 and #39. I have reviewed that one here:

      Her reference #25 is to a paper that has been retracted by the authors, as I note here:

      Unfortunately, with my upcoming schedule, I don’t know if I’ll be able to review many more of these in a timely manner, but if I do, I will post them here or in a new post with a link here.

      But ultimately, on many studies, she’s just quote mining for something and she misrepresents the study itself. Many are older studies with different viruses so their significance is limited, especially in the context of the studies we do now have available. Many she cites are in healthcare settings, which also has limited relevance to widespread public mask usage. And many just have no practical relevance. #15, for example, says that most in the general public won’t put on an N95 properly. So? The vast majority of people in the general public shouldn’t be wearing an N95 anyway. And even if they did put it on improperly, it’s still going to stop most transmission from the wearer, which is the point.

      All the best to you in your debate. Please share a link. I’d love to listen in.

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