Allergies or Sickness? Unraveling the Mystery of Concealing Infectious Diseases

What do you think when people stay quiet about infectious situations? Is it just a small white lie? 

In this episode, Under the Cortex hosts Wilson Merrell to discuss his new paper in Psychological Science titled “When and Why People Conceal Infectious Disease.” The conversation with APS’s Özge G. Fischer Baum reviews what disease concealment looks like and the factors that contribute to when people do it. Merrell highlights that 75% of US adult participants report concealing infectious illness from others and discusses the potential social pressures that might influence this decision. 

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Unedited transcript

[00:00:10.480] – APS’s Özge G. Fischer Baum 

Do you keep secrets? More specifically, do you conceal your illness from others? Is it a white lie when people hide the truth about infectious situations? This is Under the Cortex. I am Özge Gürcanlı Fischer Baum with the Association for Psychological Science. In this episode, Under the Cortex explores the predictors of concealing infectious diseases. I’m joined by Wilson Merrell from Michigan University, who has a recent article published in APS’s journal Psychological Science. Together, we are going to talk about when and why people conceal infectious disease. Wilson, thank you for joining me today. Welcome to Under the Cortex. 

[00:00:55.620] – Wilson Merrell 

Thanks so much for having me. It’s great to be here. 

[00:00:58.100] – APS’s Özge G. Fischer Baum 

This was such an interesting body of work and very relevant to our work today. What prompted you to start studying disease concealment? 

[00:01:08.340] – Wilson Merrell 

Yeah, so we got super interested in this topic, actually, before COVID even hit. So I started my PhD at the University of Michigan in 2018. And with my advisor, we were really interested in the psychology of sickness. How do people detect illness in others? And after he wrapped up this first project, we got in this idea of, well, if people use their sight and their sense of sound and smell and touch to defect illness, then maybe people want to hide illness in some way using those senses. And then COVID hit, and the world turned upside down, and our research became really relevant and also a lot harder to do because we couldn’t bring people in person. But it really all started from this idea of what is the psychology of infectious illness? And it seems like concealment was a really big part of that. 

[00:01:51.130] – APS’s Özge G. Fischer Baum 

Yes. And your study is an ambitious one. There are ten studies that you talk about. I will come to that. But before that, I want to clarify some of these concepts. So, first, how do you define concealment? And second, you talk about harmful versus mild infections. How do people define those things? 

[00:02:12.450] – Wilson Merrell 

Yeah. So first on likes of concealment, this is when you think that you’re sick with an illness that you could spread to somebody else, a common cold, the flu, or something like that. And you. You cover it up in some way. Maybe you tell people that you think you just have allergies. Maybe you dress in a different way or attribute a cough to a tickle in your throat or something that is a more active form of concealment. But concealment can also be really passive. You could just be sick in public and not say anything to anyone else. We call this omission. So you can conceal in really active ways by covering up your symptoms, or you could just not say anything to your coworkers around you or something like that. And then to your second question about illness. Harm. We’re kind of thinking of two main dimensions of illness harm, and these are drawn from, like, the risk assessment literature. And so illness harm is how severe your symptoms are. So how much disruption is there to your everyday life? Are you stuck in bed all day? Are you maybe able to go to work a little bit, but not really function that well or something like that? 

[00:03:09.590] – Wilson Merrell 

So along that dimension, and then the second one is transmissibility. So how likely do you think, if you’re interacting with other people in person, how likely do you think it is that they would come down with the illness that you have? So, illness harm to us is how severe the symptoms are and how transmissible you think those symptoms are. 

[00:03:28.040] – APS’s Özge G. Fischer Baum 

And I just want to start talking about the statistics, because when I read the article, it was fascinating. You report that around 75% of us adult participants. 75%, I just want to repeat it, reported from stealing infectious illness from others. Were you surprised by how large that number was, as I am? 

[00:03:52.600] – Wilson Merrell 

Yes, we definitely were. And we were surprised for a couple reasons. The primary reason we were surprised is that when you’re asking participants to tell kind of random researchers whether they lie or whether they behave badly, there’s often this social desirability to suppress the actual occurrence of bad behaviors, like hiding illness from others. But what we found is that participants talking about their past concealment, or even sick participants talking about current concealment or future concealment, they were pretty open with us. They would write long, open ended paragraphs about why they could justify their concealment, why they would do it in the future, and things like that. And so the fact that so many people started telling us very openly about the fact they were hiding illness from others really shaped the future studies that we were running. Cause we’re like, oh, this is something that people are comfortable telling us about. So we were definitely very surprised at the first few studies that the high prevalence of this behavior. 

[00:04:45.540] – APS’s Özge G. Fischer Baum 

Yeah, that’s also interesting, that they are just honest about it. Right. What would you say the main takeaway from your data are? 

[00:04:54.940] – Wilson Merrell 

Yeah. So I think one big takeaway is this 75% number. Just that this seems to be something that people are engaging in a lot of the time, and that simple fact warrants more exploration. But I think one of the big takeaways comes from our last studies where we recruited people who were both healthy and sick. And healthy people thought that when they were sick with more infectious illnesses, at some point in the future, they would not be likely to conceal those harmful illnesses. They said, if I’m sick with something highly harmful, I’m not gonna be very likely to conceal. But when we asked sick people who were actually sick with those highly harmful illnesses, when we asked them the same questions, they still reported high levels of concealment. So when we’re healthy, we may think that, oh, if I’m sick with something really bad, then I’ll be sure to tell people around me I won’t conceal. But when we actually become sick, something psychologically changes, and we still report high levels of concealment. 

[00:05:47.880] – APS’s Özge G. Fischer Baum 

Right. That’s very interesting. When we are healthy, we are idealists, but when we are in the situation, it switches. Yeah, there are many factors you talk about, but in one of the studies you tested, the potential for the length of the illness is a factor people might consider when deciding whether or not to hide their illnesses. So can you tell us more about this one? 

[00:06:12.660] – Wilson Merrell 

Yeah. So the motivation for this study was, in other studies, we look at how harmful an illness is, but we also thought that length of illness or this duration could be a really interesting factor. Because if you have to conceal over and over and over again for a longer duration illness, it might be harder to do, and so you might be less likely to it. But on the other hand, it might be that you’re interacting with the same interaction partners over and over, and you really want to maintain those social relationships, and so you might be less likely to do it. And so we kind of tested these competing hypotheses, and we didn’t see any difference based on duration. So whether we had people think about long illnesses or short illnesses, we’re seeing similar levels of concealment between the two. There are multiple factors that we could chalk this up to. It could be about the types of relationships or the types of audiences people are concealing from. It could be other sorts of things related to the types of activities people do during long forms of illnesses or short forms of illnesses. We weren’t able to probe that in our studies, but we didn’t find that this duration of a long illness versus short illness had any influence on concealment for us. 

[00:07:17.880] – APS’s Özge G. Fischer Baum 

Yeah, you said something in the passing. I want to follow up on that. I’m curious if we want to protect our own. So when we know the people, when we are talking about the group that we interact with frequently, are we less likely to hide our illness? 

[00:07:36.570] – Wilson Merrell 

It could be. And so we have some exploratory studies that we report in the supplement where we ask people which audiences they concealed from. So was it mostly friends and family members? Was it mostly strangers and coworkers and things like that? We find some support for the fact that maybe people conceal less frequently from their family members, their romantic partners and their friends, and maybe a little bit more so from strangers, but we’re not quite sure at this point what is the underlying mechanism for that. It might be that because you’re around your romantic partner or your family members way more frequently, it’s just harder to conceal. But we’re not exactly sure what’s driving that pattern. But that lends some support for the fact that there’s this interaction between illness duration or how many times you might have to conceal from someone, and relationship closeness. So how often you see somebody, how much you value their welfare, not getting them sick and things like that. But these are things we still need to follow up on in future projects. 

[00:08:29.820] – APS’s Özge G. Fischer Baum 

Yeah, that’s great. I’m glad you already have your future studies planned. Please let us know when you have those studies as well. 

[00:08:37.950] – Wilson Merrell 

Yeah, yeah. 

[00:08:39.800] – APS’s Özge G. Fischer Baum 

So one of the things I found fascinating is that 40% of students in your study reported lying on the symptom screeners when they are going to join a social sitting or other things. Can you tell us a little more about that? 

[00:08:59.900] – Wilson Merrell 

Yeah. So some of these studies were conducted kind of during the height of the COVID-19 pandemic. So these were like when there were lockdowns and there were mask wearing mandates, vaccine mandates and things like that. Kind of like late 2020, early 2021. And during this time, at the University of Michigan, in order to access any university buildings, you had to fill out a little symptom screener on an app. And sometimes you would need to, like, present that to someone when you’re getting into the building. And the screener would basically ask, you know, do you have a. Do you have any symptoms? Have you tested positive for COVID? Have you been around anyone with COVID or anything like that? And we found that 40% of students were not fully using the symptom screener correctly, or at least they told us they weren’t using the symptom screener correctly. And so we thought this was really interesting because it maps onto this idea of concealment, and it’s also closely tracking a measure or an intended preventative measure that a lot of institutions in the US at the time were putting into place, maybe showing that people were even being deceptive on these sorts of measures. 

[00:10:00.300] – APS’s Özge G. Fischer Baum 

Then it means that this type of preventive measures, which are important from the community health perspective, they don’t work. So do you have. This is a difficult question, yet I’m going to ask it. Do you have ideas about either how to make them more effective or what would be a better alternative. 

[00:10:22.740] – Wilson Merrell 

Yeah. So we don’t have anything in our data that’s sort of like an intervention where we’re solving this issue of concealment or anything like that. But we hope that some of our findings can provide hints for maybe future researchers to test some of these things. So one of these. One such factor is that people, when they’re sick, seem relatively insensitive to illness, harm to others. We’re seeing this effect where even very sick people are still saying they would conceal. This means that some sort of intervention targeting stay home to protect others or something like that may not be the most effective because people are insensitive to that sort of thing. Something that might be better would be something more concrete. If you are caught concealing your illness, x will happen to you, you will fail a class, you will be sent home from work and reprimanded or something like that. We don’t know if these things would be more effective. We don’t know if these sorts of interventions will necessarily be successful. And there are lots of competing psychological effects at play. But something that may focus on more concrete, immediate costs may be something that sick people respond to more than these more abstract, illness harm type appeals. 

[00:11:26.750] – Wilson Merrell 

But again, these totally need to be tested in future samples to see their efficacy and how they can scale up and things like that. 

[00:11:35.060] – APS’s Özge G. Fischer Baum 

Yeah. This like carrot versus stick type of approach. Right. Like an immediate consequence for the things. This makes me think about the different approaches that different countries took for COVID. Right. So in some countries, there were bans about being even on the street and that there were strict measures. So in your paper, you only test us based samples. What do you think your effects say about the culture in the United States? And would you expect different results in different cultures? 

[00:12:09.340] – Wilson Merrell 

I think it mainly says about the US that lots of people feel social pressures to hide the fact that they’re sick. And this is true in workplace contexts, this is true when people are going on dates or going to parties or going home to see their family, is that people feel these pressures, and it oftentimes results in this trade off of in order to achieve these social goals. Goals I’m going to conceal my infectious illness and potentially cause harm to others. That’s, I think, what our data primarily say about the US. And I think it’s an open question of how do these pressures, these social pressures people feel to kind of appear in public while they’re sick and cover up that sickness for others. How are those social pressures kind of the same or different in other countries. And so we’ve got two major projects ongoing where in one of them, where our team is collecting data from, I think, 22 different countries around the world, we’re asking these exact sorts of questions. So getting at the prevalence of disease concealment, but also asking, what sorts of social pressures do you feel to conceal? And then the second one is directly comparing some european countries to the United States, where we’re looking at different sorts of policies around health and health care and how that may influence infectious disease concealment versus other types of health concealment behaviors, like hiding the fact that you’re smoking from others. 

[00:13:23.020] – Wilson Merrell 

So these are both open questions. I think they’re highly variable by many social and institutional and cultural factors. Will see. And we’re excited to get those data in over the next few months. 

[00:13:33.160] – APS’s Özge G. Fischer Baum 

Yeah, that’s very exciting. I can think about other things as well, the number of sick days you are allowed to have. Right. So that is part of it, too, definitely. You mentioned that insurance. And it’s a great idea to compare us with other western countries to use a 22 countries. Yeah. Which are. What are those countries? 

[00:13:56.930] – Wilson Merrell 

Yeah, I mean, just a few off the top of my head. We’ve got, like, european countries like Sweden and Germany and France. We’re also collecting in, like, south asian countries like Pakistan, and east asian countries like South Korea. We’re kind of trying to get a nice representation from all the different continents. And then we’re also including measures of psychological and cultural distance from each other and from the US. So we’re trying to get a wide range of countries that have lots of cultural experiences. And we’ve got some fantastic people on the team who are experts in mathematical modeling and things like that, who are going to tell us all about these different types of cultural dimensions that could be influencing our concealment patterns in lots of new and exciting quantitative ways. 

[00:14:41.350] – APS’s Özge G. Fischer Baum 

Yeah. I will say it one more time. Let us know when you have those results. 

[00:14:45.760] – Wilson Merrell 

Definitely, yeah. 

[00:14:47.670] – APS’s Özge G. Fischer Baum 

So, going full circle, you mentioned this in the beginning, very briefly, in this study, you didn’t aim to study COVID, but it is hard to ignore the context of the last few years. How do you think your results would have been different if this was a COVID study? 

[00:15:06.900] – Wilson Merrell 

Yeah, definitely. And I can say a little bit, too, about why we didn’t want to explicitly focus on COVID here, even though, as you say, it’s hard to ignore the presence of COVID in some of our studies, people’s motivations to avoid infectious illness are very deep rooted in our evolutionary history, feelings like disgust and avoidance, and social isolation. These are things that not only humans experience, but also non human primates and other types of animals. So disease is a very old thing that we’ve had to deal with. Pandemics, and specifically COVID, are very new things. These are leading to lots of new methods that are not necessarily ingrained in our evolutionary history. The fact that we’re able to. To travel across the country in a few days or have disease linked to specific political and cultural outcomes and things like that. So all this to say that COVID was a very specific case of infectious disease avoidance in the US. It was highly tied to political actions and the political sphere, both in terms of whether this is a real thing, whether people should get vaccinated, should you follow the rules? And for a lot of the pandemic, you might have seen specific types of concealment behaviors for COVID, specifically, falling along political and ideological lines. 

[00:16:23.830] – Wilson Merrell 

So I think if we were to make a COVID study about concealment, we would have to include a lot more political implications and moral implications of what does it mean for people who hold certain types of identities, maybe Democrats versus Republicans, to conceal, specifically COVID versus other types of respiratory illnesses. The other thing that we might see is that COVID was a really quickly evolving situation, both in learning what the symptoms were, both in learning what it meant to become sick with it. It’s very. At different times during the pandemic, people have very different interpretations of someone who was sick with COVID if they had been vaccinated versus hadn’t been vaccinated. That’s, of course, very highly correlated with political ideology, as I was just talking about. And so COVID was a case of infectious disease avoidance. But it was also a case of all this very proximate level. Social identities at play, political ideologies at play, and things like that. And so I think we could test some interesting patterns related to COVID and concealment. But one of the big cases we’re making our paper here is that infectious disease, concealment, was not born out of the COVID-19 pandemic. 

[00:17:30.040] – Wilson Merrell 

This is reflecting much deeper seeded and fundamental social pressures that people feel to appear healthy around others. 

[00:17:37.560] – APS’s Özge G. Fischer Baum 

Basically, I totally hear what you say about COVID being its own thing, and it had its own vaccination. And, of course, like anything, it turned into something political, especially in this country. So, yeah, your decision definitely makes sense to me. So, Wilson, this was a great conversation. Is there anything else that you like to share with our speakers? 

[00:18:04.520] – Wilson Merrell 

I think two things. First, I’ll just highlight a point I made earlier. And this is something that’s been coming up in response to how people have been kind of talking about our article either online or have talked to me about it in person. And I think when you hear this 75% number, people can sometimes get scared of like, oh, I need to be really careful because everyone around me is a jerk or they could be at risk of concealing or something like that. And I think that is a possible interpretation. But I’d also like to leave people with a second interpretation. That is because concealment is such a prevalent behavior, it means that a lot of us are feeling these pressures to conceal. It means that there are social things going on in our lives, at the interpersonal level, at the intergroup level, at the institutional level, that are making people feel like, I need to do this thing. It’s not that 75% of the people are jerks, it’s that 75% of the people at least telling us feel these kinds of social pressures. And I think that that sort of a reframing is both helpful for researchers and people in the lay public when they think about setting policies and how they own they feel themselves when they’re sick and make decisions when they themselves are sick about these social pressures. 

[00:19:12.890] – Wilson Merrell 

So that’s one thing. And the second thing is, I just want to give a huge shout out to my co authors and collaborators on this project, my grad student co op mate at the University of Michigan, Soyuzhoi, and then my primary advisor, Doctor Josh Ackerman at the University of Michigan. So they were the other two co authors on this project. Just fantastic to work with and couldn’t really do any of this without them. So very thankful to them. 

[00:19:34.010] – APS’s Özge G. Fischer Baum 

Yeah, what you said is really important. We are all humans. We are social creatures. So disease concealment sounds like it is at the interplay between us trying to be social and fighting off biological pressures at the same time. Totally, Wilson, this was wonderful. Thank you very much. 

[00:19:57.080] – Wilson Merrell 

Thank you. 

[00:20:01.710] – APS’s Özge G. Fischer Baum 

This is Özge Gürcanlı Fischer Baum with APS, and I have been speaking to Wilson Merrell from Michigan University. If you want to know more about his research, visit 

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