Pandemics and the future of urban density: Michael
Hooper on hygiene, public perception and the “urban
penalty”
gsd.harvard.edu/2020/04/have-we-embraced-urban-density-to-our-own-peril-michael-hooper-on-hygiene-publicperception-and-the-urban-penalty-in-a-global-pandemic
April 13, 2020
April 13, 2020
Text by Michael Hooper
Departments
Department of Urban Planning and Design
A 1908 illustration from the Virginia Health Bulletin shows urban
diseases threatening the bucolic conditions of suburban life.
Courtesy: the Virginia Health Bulletin.
The Covid-19 pandemic has raised many challenging questions for planners, architects,
and policymakers around the issue of urban density. While researchers have spent
decades making the case for density, there are worries that the threat posed by the
Covid-19 virus will cause cities to be seen as sites of risk and for densification to fall out
of favor. Indeed, many efforts to control the spread of virus have explicitly focused on
strategies of “de-densification.” This includes at Harvard, where undergraduates were
sent home to reduce the density of people on campus.
Many planners, in particular, have expressed worry that the focus on de-densification
might mean that people are less willing to embrace density once the pandemic is over.
This is of concern since—as the implications of climate change have become apparent
and cities are forced to address the energy and environmental costs associated with
diffuse development and sprawl—planners have viewed densification as a key strategy
toward achieving sustainability goals. Despite worries that momentum behind compact
cities, smart growth, and density writ large might be lost due to the pandemic, it has
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been difficult to predict the potential impact because the relationship between hygiene
concerns and density perceptions is poorly understood and has been the subject of very
little research.
In late medieval times, wealthy residents of European cities often retreated from cities
during plagues. Following a similar pattern, in the present Covid-19 pandemic, news
stories have reported instances of the wealthy fleeing cities for rural holiday properties
or second homes.
Michael HooperOn the public perception of cities as sites of squalor, and suburban
environments as bucolic and safe
Prior to the pandemic, I was intrigued by the relative lack of empirical, contemporary
research on the relationship between hygiene and attitudes toward density. This gap
was particularly interesting because there is a substantial body of fascinating tangential
evidence that suggests people’s attitudes to urban density might be influenced by
hygiene concerns. Historically, for example, dense settlements have been associated
with increased risk of disease. Scholars have argued that virtually all human infectious
diseases due to microorganisms arose out of the emergence of urbanism (1).
As a result of the association between dense urban settlements and disease
transmission—a phenomenon referred to in public health as the “urban penalty”—
dispersal from cities has sometimes been viewed as an effective response to infectious
disease outbreaks. In late medieval times, wealthy residents of European cities often
retreated from cities during plagues (2,3). Similarly, students and faculty at Oxford
University moved to rural sites during times of outbreak. The connection between
perceptions of hygiene, health, and urban density can also be seen in late 19th- and
early 20th-century public health publications (such as in the image accompanying this
article), which often depicted cities as sites of squalor and suburban environments as
bucolic and safe (4). Following a similar pattern, in the present Covid-19 pandemic,
news stories have reported instances of the wealthy fleeing cities for rural holiday
properties or second homes (5). From a biomedical perspective, studies have shown
that population density is positively associated with transmission rates for diseases
transmitted via fecal-oral and respiratory routes, including influenza (6,7).
In the face of the historical and contemporary evidence that cities may be viewed as
sites of increased risk from infectious illnesses, are people’s perceptions of density
actually influenced by hygiene concerns? The seeming absence of any direct research
into this question led me to design an experiment to explore this topic. The experiment
drew on research in psychology and related behavioral sciences that has argued that
“most of a person’s everyday life is determined not by their conscious intentions but by
mental processes…that operate outside of conscious awareness. (8)”
One aspect of the extensive research on the subconscious factors shaping perceptions
has concentrated on “priming”—an effect in which exposure to one stimulus affects
response to another. Priming studies have shown, for example, that thinking about
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professors improves performance in Trivial Pursuit and that reading words associated
with the elderly, such as “Florida,” is associated with people walking more slowly. In
another study, individuals who were exposed to a reminder, or “prime,” related to
physical cleansing, such as a bottle of hand sanitizer or a request to use hand wipes,
reported being more politically and morally conservative (9). Priming studies have
become nearly ubiquitous in social psychology and related behavioral fields, but they
have seldom examined urban contexts and have not addressed the issue of density. My
experiment sought to address this gap by examining if perceptions of density were, like
many other social, political, and moral attitudes, influenceable via priming.
The experiment took place at the Harvard Decision Science Laboratory, a facility that
provides space for behavioral experiments. It involved 437 participants participating in
two visual preference surveys and two narrative scenarios. Participants were randomly
assigned to four groups. Those in the control group viewed and scored images—from the
Lincoln Institute’s Visualizing Density Database—of different density settings. They also
answered questions regarding a hypothetical density increase in their neighborhood.
Participants in the other groups, who were placed in three separate rooms, undertook
these same tasks, but were exposed to three different hygiene-related primes. One
group was asked to hand sanitize before and after answering the questions due to risk
from colds and flu; one group found banana peels left in their workspace and had to
dispose of them in the trash before answering the questions; and the last group was
exposed to fart spray (yes, fart spray!) that had been introduced into the room at the
start of the session. Primes of each of these kinds have been shown to influence political
and social attitudes and moral judgments and the goal was to see if perceptions of
density were similarly malleable.
The study’s findings showed no consistent influence of hygiene priming on density
perceptions. This is surprising since the vast body of priming research shows that
virtually all perceptions and attitudes tested thus far can apparently be primed. Had
density perceptions been found to be similarly malleable, it might have opened up a
range of subconscious interventions to modify these perceptions. While this may sound
far-fetched or from the realm of science fiction, governments and private companies
have already begun to undertake such efforts, although not yet in earnest around urban
planning.
There are many ways in which priming-related research has already been practically,
and sometimes worryingly, deployed. In public policy more broadly, for example, many
governments have sought to deploy “nudging” to influence citizen behavior. In this vein,
the government of the United Kingdom has established a Behavioral Insights Team, or
“Nudge Unit,” that seeks to use behavioral research to “enable people to make ‘better
choices for themselves.’” (10) In the private sector, priming-related research—including
such studies as one arguing that the smell of chocolate motivates people to purchase
more books—has led companies to develop scent technologies that can distribute over
300 different smells into shops to influence customer perceptions and purchasing
behavior.
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Unlike the vast majority of perceptions addressed in the priming literature, the
experiment described here suggests that density perceptions are relatively impervious to
hygiene priming. This finding has considerable planning implications. First, it may go
some way toward assuaging planners’ and designers’ concerns that the current Covid-19
pandemic will influence people’s attitudes away from density. The study showed that,
while people have varying density preferences, these are not significantly altered by
exposure to hygiene cues. While the results suggest that the pandemic may not affect
density preferences, they do help explain why it also so hard for planners and designers
to introduce interventions that change urban densities.
The experiment indicates that density preferences may be more stable than many of the
other perceptions studied so far and, correspondingly, efforts to change densities will
likely have to be accompanied by extensive efforts to win over skeptical publics. Beyond
considering the specific issues of hygiene and density, the study described here also
argues for much greater attention to the behavioral dimensions of planning and design
and for expanding the range of methods, including greater use of experiments, in urban
planning research.
Michael Hooper is Associate Professor of Urban Planning at the Harvard Graduate
School of Design. The results of his study “Flatulence, Filth, and Urban Form: Do
Primes for Hygiene Influence Perceptions of Urban Density?” were published in the
Journal of Planning Education and Research .
(1) James C. Scott, Against the Grain: A Deep History of the Earliest States (New
Haven, CT: Yale University Press, 2017).
(2) Ann G. Carmichael, Plague and the Poor in Renaissance Florence (Cambridge:
Cambridge University Press, 1986).
(3) William J Courtenay, “The Effect of the Black Death on English Higher Education,”
Speculum 55, no. 4 (October 1980): 696-714.
(4) Virginia Department of Health, “Scarlet fever, diphtheria, and disinfection,”
Virginia Health Bulletin 1, no. 6 (1908): 216.
(5) Amanda Holpuch, “Luxury resorts face coronavirus crisis as the 1% flee cities for
holiday hideaways,” The Guardian, April 4, 2020.
(6) Alirol, E., L. Getaz, B. Stoll, F. Chappuis, and L. Loutan. 2011. “Urbanisation and
Infectious Diseases in a Globalized World.” The Lancet Infectious Diseases 11 (2): 131141.
(7) Xiao, H., X. Lin, G. Chowell, C. Huang, L. Gao, B. Chen, Z. Wang, L. Zhou, X. He, H.
Liu, X. Zhang, and H. Yang. 2014. “Urban Structure and the Risk of Influenza A (H1N1)
Outbreaks in Municipal Districts.” Chinese Science Bulletin 59 (5-6): 554-562.
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(8) John A. Bargh and Tanya L. Chartrand, “The Unbearable Automaticity of Being,”
American Psychologist 54, no. 7 (July 1999): 462–79.
(9) Erik G. Helzer and David A. Pizarro, “Dirty Liberals! Reminders of Physical
Cleanliness Influence Moral and Political Attitudes,” Psychological Science 22, no. 4
(March 2011): 517-522.
(10) United Kingdom Cabinet Office. 2018. “Behavioural Insights Team.” Accessed
June 15, 2018. https://www.behaviouralinsights.co.uk/.
© 2020 President and Fellows of Harvard College
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