Joshua Epstein is a professor of epidemiology in the School of Global Public Health at NYU and director of NYU’s Agent-Based Modeling Laboratory, with affiliated appointments at NYU’s Courant Institute of Mathematical Sciences and Department of Politics. He is the author of Agent_Zero: Toward Neurocognitive Foundations for Generative Social Science. Recently he spoke by telephone about the COVID crisis with Commonweal contributing editor Rand Richards Cooper. The interview has been edited and condensed.
Rand Richards Cooper: In a Politico article, you wrote about “the contagion of fear” and its role in pandemics. Can you describe your epidemiological modeling work and what it reveals about fear and contagion?
Joshua Epstein: Most classical mathematical epidemiology ignores behavioral adaptation. People in the models just keep mixing together and spreading disease, for example, and don’t self-isolate on their own. I introduced methods to study how fear of the pathogen can produce self-isolation. I call these coupled contagion models, where a disease is spreading, but fear of the disease is also spreading, and the two contagions interact to produce multiple waves. The core narrative is this: if the disease is high, people get scared, and they spread their fear and put themselves in isolation. This takes fuel out of the epidemic, suppressing the spread. When the spread gets low, people's fear starts to diminish, and they come out of isolation. The problem is that there can still be infection in the community. Prematurely relaxing self-isolation and distancing pours fuel—in the form of susceptible healthy people—onto these infective embers, and the thing can explode in a new wave. That's what we saw in the Spanish flu pandemic of 1918. And it's what we're worrying about with COVID-19—cycles of vigilance and complacency that can produce oscillations of just this sort.
RRC: By mid-March, my family had self-isolated completely, even though at the time we didn't know a single person who’d even been sick. I’d always assumed that people need fear to be immediate and personal in order to be sufficiently motivated to make such drastic changes. Is that wrong?
JE: Fear of disease can spread without direct exposure to the disease itself, and can spread faster and wider than the disease. To get the disease you have to bump into a sick person, but there are many more channels for transmitting fear. And things can spread like wildfire on social media. We see that a lot—not just in epidemics but in financial panics and other collective dynamics. There's a lot of fascinating work using social media to study this spread. At my lab we build agent-based models. These are artificial societies of software people that we build on computers. We let them interact, and they can spread disease, they can spread rumors, they can spread fear. I developed a next-generation software person named Agent Zero who has a fear module, a deliberative module, and a social module. Agent Zero’s overt behavior is the result of all these forces.
The system of fear is very ancient. The amygdala complex in the brain is as old as vertebrate history. We're hardwired to learn fears—it’s a big survival component. And we can spread the fear to one another. There are experiments in neuroscience where one person is conditioned to fear a blue light through having a shock cuff activated when the light goes on; eventually the person clenches up in fear from the light alone. The real core of the experiment is where someone is not wearing the shock cuff, but just observing the person who’s being conditioned. And then you shine the light at the observer, and she’s afraid, too. Watching people experience fear can make you afraid.
RRC: In the context of an epidemic, fear sounds almost entirely salutary. What’s the downside?
JE: Yes, fear helps suppress the disease, as we discussed before. But it is also double-edged. That same fear also closes down a lot of social interaction and economic life. And we can acquire and spread all kinds of baseless fears and biases by the same mechanism. An important step, I think, is to understand that we’re subject to these unconscious evolved forces. If we had a better appreciation of our fears and how they happen, and how baseless they can actually be, it would help us avoid being manipulated politically. And that brings in another fear that worries me a great deal— fear of vaccines. The WHO is now listing vaccine refusal as one of the top ten threats to global health. We're seeing the resurgence of measles and even polio out of these really baseless fears of vaccination.
RRC: I’ve been struck by how the daily lifestyle precautions we’ve adopted create what we'd normally think of as a kind of paranoid state. It’s like living your whole life as a TSA airport-security procedure. How can people sort out prudence from panic? Are we too afraid or are we not afraid enough?