New technique can reconstruct history of every mature cell’s development 08-11

All humans begin life as a single cell that divides repeatedly to form two, then four, then eight cells, all the way up to the 26 billion or so that make up a newborn. Tracing how and when those 26 billion cells arise from one zygote is the grand challenge of developmental biology, a field that so far has only been able to capture and analyze snapshots of the development process.

Now, a new method developed by scientists at the Wyss Institute and Harvard Medical School (HMS) brings that task into the realm of possibility using evolving genetic barcodes that record the process of cell division in developing mice, enabling the lineage of every cell in a mouse’s body to be traced back to its single-celled origin.

The research is published today in Science as a First Release article.

“Current lineage-tracking methods can only show snapshots in time, because you have to physically stop the development process to see how the cells look at each stage, almost like looking at individual frames of a motion picture,” said senior author George Church, who is a core faculty member at the Wyss Institute, professor of genetics at HMS, and professor of health sciences and technology at Harvard and MIT. “This barcode recording method allows us to reconstruct the complete history of every mature cell’s development, which is like playing the full motion picture backwards in real time.”

The genetic barcodes are created using a special type of DNA sequence that encodes a modified RNA molecule called a homing guide RNA (hgRNA), which was described in a previous paper. The hgRNA molecules are engineered such that when the enzyme Cas9 (of CRISPR-Cas9 fame) is present, the hgRNA will guide the Cas9 to its own hgRNA sequence in the genome, which Cas9 then cuts. When the cell repairs that cut, it can introduce genetic mutations in the hgRNA sequence, which accumulate over time to create a unique barcode.

The researchers implemented the hgRNA-Cas9 system in mice by creating a “founder mouse” that had 60 different hgRNA sequences scattered throughout its genome. They then crossed the founder mouse with mice that expressed the Cas9 protein, producing zygotes whose hgRNA sequences started being cut and mutated shortly after fertilization.

“Starting with the zygote and continuing through all of its progeny, every time a cell divides there’s a chance that its daughter cells’ hgRNAs will mutate,” explained first author Reza Kalhor, a postdoctoral research fellow at the Wyss Institute and HMS. “In each generation, all the cells acquire their own unique mutations in addition to the ones they inherit from their mother cell, so we can trace how closely related different cells are by comparing which mutations they have.”

Each hgRNA can produce hundreds of mutant alleles; collectively, they can generate a unique barcode that contains the full developmental lineage of each of the approximately 10 billion cells in an adult mouse.

The ability to continuously record cells’ development also allowed the researchers to resolve a longstanding question regarding the embryonic brain: Does it distinguish its front from its back end first, or its left from its right side? By comparing the hgRNA mutation barcodes present in cells taken from different parts of two mice’s brains, they found that neurons from the left side of each brain region were more closely related to neurons from the right side of the same region than to neurons from the left side of neighboring regions. This result suggested that front-back brain patterning emerges before left-right patterning in central nervous system development.

“This method allows us to take the final developmental stage of a model organism and from there reconstruct a full lineage tree all the way back to its single-cell stage. It’s an ambitious goal that will certainly take many labs several years to realize, but this paper represents an important step in getting there,” said Church.

The researchers are now focusing on improving their readout techniques so that they can analyze the barcodes of individual cells and reconstruct the lineage tree that has been recorded.

“Being able to record cells continuously over time is a huge milestone in developmental biology that promises to exponentially increase our understanding of the process by which a single cell grows to form to an adult animal and, if applied to disease models, it could provide entirely new insights into how diseases, such as cancer, emerge,” said Donald Ingber, director of the Wyss Institute. Ingber is also the Judah Folkman Professor of Vascular Biology at HMS and the vascular biology program at Boston Children’s Hospital, and professor of bioengineering at Harvard’s John A. Paulson School of Engineering and Applied Sciences.

Additional authors of the paper include Kian Kalhor from Sharif University of Technology in Tehran, Iran; Leo Mejia from HMS; Kathleen Leeper and Amanda Graveline from the Wyss Institute; and Prashant Mali, associate professor at the University of California, San Diego.

This research was supported by the National Institutes of Health and the Intelligence Advanced Research Projects Activity.

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For new medicines, turn to pioneers 05-21

Most transformative medicines originate in curiosity-driven science, evidence says....

Would we be wise to prioritize “shovel-ready” science over curiosity-driven, fundamental research programs? In the long term, would that set the stage for the discovery of more medicines?
To find solid answers to these questions, scientists at Harvard and the Novartis Institute for Biomedical Research (NIBR), publishing in Science Translational Medicine, looked deep into the discovery of drugs and showed that, in fact, fundamental research is “the best route to the generation of powerful new medicines.”

“The discoveries that lead to the creation of a new medicine do not usually originate in an experiment that sets out to make a drug. Rather, they have their origins in a study — or many studies — that seek to understand a biological or chemical process,” said Mark Fishman, one of three authors of the study. “And often many years pass, and much scientific evidence accumulates, before someone realizes that maybe this work holds relevance to a medical therapy. Only in hindsight does it seem obvious.”

Fishman is a professor in the Harvard Department of Stem Cell and Regenerative Biology, a faculty member of the Harvard Stem Cell Institute, and former president of NIBR. He is a consultant for Novartis and MPM Capital, and is on the board of directors of Semma Therapeutics and the scientific advisory board of Tenaya Therapeutics.

CRISPR-cas9 is a good example of discovery biology that opened new opportunities in therapeutics. It started as a study of how bacteria resist infection by viruses. Scientists figured out how the tools that bacteria use to cut the DNA of an invading virus could be used to edit the human genome, and possibly to target genetic diseases directly.

The origins of CRISPR-Cas9 were not utilitarian, but those discoveries have the potential to open a new field of genomic medicine.

Blood pressure medicines would never have been created without the discovery of the role of renin (a renal extract) in regulating blood pressure in 1898.

Blood pressure medication is another example of how fundamental discoveries can lead to transformative medicines.

People who suffer from high blood pressure often take drugs that act by blocking the angiotensin-converting enzyme. Those medicines would never have been created without the discovery of the role of renin (a renal extract) in regulating blood pressure in 1898, or without the discovery of angiotensin in 1939, or without the solid understanding of how the enzyme works, shown in 1956.

This work was not tied earlier to making pills for hypertension, mainly because hypertension was generally believed to be harmless until the 1950s, when studies showed its relationship to heart disease. Before then, the control of blood pressure was itself a fundamental science, beginning with Stephen Hales’ measurement  of blood pressure in a horse in 1733.

The discovery of ACE inhibitors really reflects the convergence of two fields of fundamental, curiosity-driven discovery.

Yet some observers believe that projects that can demonstrate up front that they could produce something useful should take priority over projects that explore fundamental questions. Would there be many more medicines if academics focused more on programs with practical outcomes? How would that shift affect people in the future?

To find answers, Fishman and his colleagues investigated the many scientific and historical paths that have led to new drugs. The study they produced is a contemporary look at the evidence linking basic research to new medicines.

The authors used a list of the 28 drugs defined by other scientists as the “most transformative” medicines in the United States between 1985 and 2009. The group examined:
Whether the drug’s discovery began with an observation about the roots of disease;
Whether the biologist believed that it would be relevant to making a new medicine; and
How long it took to realize that.

To mitigate bias, the researchers repeatedly corroborated the assignment with outside experts.
They found that eight out of 10 of the medicines on their list led back to a fundamental discovery — or series of discoveries — without a clear path to a new drug.

The average time from discovery to new drug approval was 30 years, the majority of which was usually spent in academia, before pharmaceutical or biotechnology companies started the relevant drug development programs.

Fishman concluded, “We cannot predict which fundamental discovery will lead to a new drug. But I would say, from this work and my experiences both as a drug discoverer and a fundamental scientist, that the foundation for the next wave of great drugs is being set today by scientists driven by curiosity about the workings of nature.”

What industry and academic leaders say..

Leaders in biomedicine from industry, business, and academia warmly welcome this new body of evidence, as it supports the case for funding curiosity-driven, non-directed, fundamental research into the workings of life.

“This perspective on drug discovery reminds all of us that while many in both industry and academia have been advocating for a more rational approach to R&D, the scientific substrate we depend on results from a less than orderly process. The impact of basic research and sound science is often unpredictable and underestimated. With several telling examples, the authors illustrate how they can have a ripple effect through our field.”

– Jean-François Formela, M.D., Partner, Atlas Venture...

“The paper presents a compelling argument for investing in fundamental, curiosity-driven science. If it often takes decades to recognize when a new discovery should prompt a search for targeted therapeutics, we should continue to incentivize academic scientists to follow their nose and not their wallets.”

– George Daley, M.D., Ph.D., Dean of the Faculty of Medicine, Caroline Shields Walker Professor of Medicine, and Professor of Biological Chemistry and Molecular Pharmacology at Harvard Medical School

“There is a famous story of a drunk looking for his lost keys under a streetlight because the light is better there. As Mark reminds us, if we only look for cures where the light has already shone, we will make few if any new discoveries. Basic research shines a light into the dark corners of our understanding, and by that light we can find wonderful new things.”

— Dr Laurie Glimcher, M.D., President and CEO of the Dana-Farber Cancer Institute and Richard and Susan Smith Professor of Medicine at Harvard Medical School

“The importance of fundamental discovery to advances in medicine has long been a central tenet of academic medicine, and it is wonderful to see that tenet supported by this historical analysis. For those of us committed to supporting this pipeline, it is a critical reminder that young scientists must be supported to pursue out-of-the-box questions and even new fields. In the end, that is one of the key social goods that a research university provides to future generations.”

— Katrina Armstrong, M.D., M.S.C.E., Physician-in-Chief, Department of Medicine, Massachusetts General Hospital

“Human genetics is powering important advances in translational medicine, opening new doors to treatments for both common and rare diseases at an increasingly rapid pace. Yet, these discoveries still require fundamental, basic scientific understanding into the drug targets’ mechanism of action. In this way, the potential of the science can be unlocked through a combination of curiosity, agility, and cross-functional collaboration to pursue novel therapeutic modalities like gene and cellular therapies, living biologics, and devices. This paper illustrates the value of following the science with an emphasis on practical outcomes and is highly relevant in today’s competitive biopharmaceutical environment, where much of the low-hanging fruit has already been harvested.”

– Andy Plump, M.D., Ph.D., Chief Medical and Scientific Officer, Takeda Pharmaceutical Co.
“Medicine depends on scientists asking questions, collectively and over generations, about how nature works. The evidence provided by Fishman and colleagues supports an already strong argument for continued and expanded funding of our nation’s primary source of fundamental science: the NIH and the NSF.”

– Douglas Melton, Ph.D., Xander University Professor at Harvard, Investigator of the Howard Hughes Medical Institute, and co-director of the Harvard Stem Cell Institute

“Just as we cannot translate a language we do not understand, translational medicine cannot exist without fundamental insights to be converted into effective therapies. In their excellent review, Fishman and his colleagues bring the factual evidence needed to enrich the current debate about the optimal use of public funding of biomedical research. The product of public research funding should be primarily fundamental knowledge. The product of industrial R&D should be primarily transformative products based on this knowledge.”

— Elias Zerhouni, M.D., President Global R&D Sanofi, former Director of the National Institutes of Health, 2002-2008

“Fundamental research is the driver of scientific knowledge. This paper demonstrates that fundamental research led to most of the transformative medicines approved by the FDA between 1985 and 2009. Because many genes and genetic pathways are evolutionarily conserved, discoveries made from studies of organisms that are highly tractable experimentally, such as yeasts, worms, and flies, have often led to and been integrated with findings from studies of more complex organisms to reveal the bases of human disease and identify novel therapeutic targets.”

– H. Robert Horvitz, Nobel Laureate; David H. Koch Professor, Member of the McGovern Institute for Brain Research and of the David H. Koch Institute for Integrative Cancer Research, and Howard Hughes Medical Institute Investigator at Massachusetts Institute of Technology

“This meticulous and important study of the origin of today’s most successful drugs finds convincingly that the path to discovery lies through untargeted fundamental research. The authors’ clear analysis is an effective counter to today’s restless investors, academic leaders, and philanthropists, whose impatience with academic discovery has itself become an impediment to the conquest of disease.”

— Marc Kirschner, John Franklin Enders University Professor, Department of Systems Biology, Harvard Medical School

“Some ask if there is a Return on Investment (ROI) in basic biomedical research. With transformative therapies as the ‘R,’ this work traces the path back to the starting ‘I,’ and repeatedly turns up untargeted academic discoveries — not infrequently, two or more that are unrelated to each other. Conclusion? A nation that wants the ‘R’ to keep coming must maintain, or better, step up the ‘I’: that is, funding for curiosity-driven, basic research.”

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The Airbnb Effect: Cheaper Rooms for Travelers, Less Revenue for Hotels 03-06

Hotels enjoy their highest profits when rooms are most in demand, like during holidays and big events. Unfortunately for them, Airbnb is taking away some of that pricing power, according to new research by Chiara Farronato and Andrey Fradkin. 

Image credit : Shyam's Imagination Library

Airbnb is revolutionizing the lodging market by keeping hotel rates in check and making
additional rooms available in the country's hottest travel spots during peak periods when hotel rooms often sell out and rates skyrocket, a new study shows.

That's bad news for hotels, which have traditionally earned their biggest margins when rooms were scarce and customers were forced to pay higher rates—such as in Midtown Manhattan on New Year's Eve. And it's good news for travelers who don't have to pay through the roof to get a roof over their heads during holidays or for big events.

"The benefits to travelers and the reduction in pricing power of hotels is really concentrated in particular cities during certain times," says Chiara Farronato, a co-author of the study. "When hotels are fully booked, Airbnb expands the capacity for rooms."

Released today, the research shows that in the 10 cities with the largest Airbnb market share in the US, the entry of Airbnb resulted in 1.3 percent fewer hotel nights booked and a 1.5 percent loss in hotel revenue.

The paper, The Welfare Effects of Peer Entry in the Accommodation Market: The Case of Airbnb, was written by Farronato, a Harvard Business School assistant professor, and Andrey Fradkin, postdoctoral fellow at the Initiative on the Digital Economy at the Massachusetts Institute of Technology.

"You might find a Fifth Avenue apartment or a place by the beach at a more reasonable price than you would if Airbnb wasn't an option"

Competition between traditional hotels and Airbnb is intensifying. Last Friday, Airbnb announced it is expanding its "experiences" offerings to an additional 1,000 cities. Meanwhile, the lodging industry is not only adding its own offerings, but stepping up lobbying efforts in local and federal circles for stricter regulations governing Airbnb.

The study focused on data from 2014, and the impact on hotels could be even greater today given Airbnb's strong growth since then.

In addition to access to more rooms, travelers reaped other rewards in places where Airbnb competed with hotels, the study shows. During busy travel times, guests enjoyed an average "consumer surplus" of $57 per night. This surplus didn't necessarily amount to more money in a visitor's pocket, but it did mean better accommodations at more reasonable prices, Farronato explains.

"Consumers don't always pay a lower price," Farronato says. "What changes is the quality of the listings. You might find a Fifth Avenue apartment or a place by the beach at a more reasonable price than you would if Airbnb wasn't an option. Or a listing might have additional amenities, like a kitchen. And if you still prefer a hotel room, competition from Airbnb means you'll pay a lower price for it."

Airbnb's rapid growth

Airbnb, an online community marketplace where people can list and book short-term lodging accommodations around the world, was founded in 2008 and has grown rapidly at a time when plenty of other industry-disrupting platforms have flourished, including Uber, Craigslist, and Spotify.

Airbnb offers listings in 191 countries, and its total number of listings—4 million-—is higher than the top five major hotel brands combined.

To compare the performance of hotels versus Airbnb, the researchers used hotel data from STR, which tracks more than 161,000 hotels, as well as proprietary data provided by Airbnb, creating "the perfect setup to study market competition between new online platforms and traditional service providers," Farronato says. They studied prices and occupancy rates in 50 major US cities between 2011 and 2014, targeting markets with the largest number of hotels.

During the study period, Airbnb made a relatively small dent in the overall short-term accommodations market. Its rooms represented 4 percent of all guests and less than 1 percent of total housing units across all cities. And Airbnb didn't have much effect on hotel occupancy rates overall. Since Airbnb bookings occurred especially when hotels were already near full capacity, a large share of these bookings—between 40 and 60 percent—would not have been made at hotels if Airbnb wasn't an option.

The San Francisco-based home-sharing platform still made its mark on the hotel industry, however. The researchers found that Airbnb's growth through 2014 reduced hotel variable profits by up to 3.7 percent in the 10 US cities with the largest Airbnb presence.

This effect was particularly strong in cities with limited hotel capacity during peak demand days. On those days, hotel room prices were affected relatively more than occupancy rates, meaning that a hotel in one of these cities might still be fully booked during a peak period, but the competition from Airbnb may have forced the hotel to lower its rates for those rooms.

Airbnb rooms were more plentiful in cities with a big demand for accommodations, as well as areas with higher-priced hotels, like New York, Los Angeles, and San Francisco. In other places such as Oklahoma City and Memphis, however, listings were sparse by comparison.

"It's important to note that not all cities are affected by Airbnb," Farronato says. "In Atlanta or Houston, there are enough hotel rooms to satisfy the demand, so peer hosts don't find it attractive to enter the market as much there."

Within each city, more Airbnb rooms cropped up during popular travel periods, such as Christmas and the summer. Sports games, festivals, and other events also led to a spike in listings. In Cambridge, Mass., the biggest listing period came during college graduation time.

And that's the beauty of Airbnb for hosts: They can respond quickly to market conditions, keeping their homes for private use when prices are low and hosting travelers only when the demand for rooms—and the payoff from renting them—is highest.

"As a host, you might not want to risk renting out your place for just $80 a night," Farronato says. "But when the pope comes to Philly, and hotel prices are $200, it becomes worth your while to put your spare room out for rent. Airbnb hosts are in this sweet spot where they can take advantage of only the high-demand periods and stay out of the market at other times."

Hotels fight back

Lodging groups have not taken Airbnb's incursions lightly. Starting in 2016, the American Hotel and Lodging Association backed efforts by the Federal Trade Commission and the state of New York to investigate Airbnb's impact on local housing prices, according to The New York Times. The AHLA also launched a campaign to portray Airbnb hosts as being, in reality, commercial operators looking to compete illegally with hotels.

As margin pressure increases from Airbnb properties over time, hotels will be forced to step up the competition even more. The problem: fixed investment costs. The demand for rooms is always fluctuating, but it's not efficient for hotels to build enough capacity to satisfy the peaks, so they are challenged with finding the right middle ground.

"When the pope comes to Philly, and hotel prices are $200, it becomes worth your while to put your spare room out for rent"

"If you have too much capacity, you will have a lot of empty rooms most of the time," Farronato says. "And if you have too little capacity, you won't be able to satisfy the demand, and Airbnb hosts will come in and drive prices down when demand is high."

Farronato said home-sharing platforms are likely to gain even more ground over time as consumers become increasingly aware of their benefits, so it's important for hotels to find creative ways to compete. At the same time, as cities add home-sharing regulations, both the benefits of Airbnb to consumers and hosts, as well as the effects on hotels, will likely become less pronounced.

Just as Airbnb is adding experience packages to its home-rental offerings, so too are hotels such as Marriott International. And maybe hotels could even find ways to alter their building spaces on the fly to accommodate the peaks and valleys of consumer demand.

"You could have rooms that quickly and dynamically change from hotel rooms into conference rooms. So you can have this flexible capacity of rooms that are available on New Year's Eve, but become conference spaces at other times," Farronato says. "It requires a whole new way of designing things. It's all worth thinking about."

Reproduced from Harvard Business Working Knowledge

How to Get People Addicted to a Good Habit 02-16

Researchers set out to discover whether they could induce households to develop a healthy habit of handwashing with soap. Here a young boy in West Bengal, India, uses a wall-mounted soap dispenser provided by the research team. (Source: Reshmann Hussam)

Reshmaan Hussam and colleagues used experimental interventions to determine if people could be persuaded to develop a healthy habit. Potentially at stake: the lives of more than a million children.

A few years ago, Reshmaan Hussam and colleagues decided to find out why many people in the developing world fail to wash their hands with soap, despite lifesaving benefits.

Every year more than a million children under the age of five die from diarrheal diseases and pneumonia. Washing hands with soap before meals can dramatically reduce rates of both diarrhea and acute respiratory infections.

To that end, major health organizations have poured a lot of money into handwashing education campaigns in the developing world, but to little avail. Even when made aware of the importance of a simple activity, and even when provided with free supplies, people continue to wash their hands without soap—if they wash their hands at all.

“If you look at these public health initiatives, you see that they are often a complicated combination of interventions: songs and dances and plays and free soap and water dispensers,” says Hussam, an assistant professor at Harvard Business School whose research lies at the intersection of development, behavioral, and health economics. “Which means that when these initiatives don’t work, nobody can say why.”

When Hussam and her fellow researchers conducted their initial survey of several thousand rural households in West Bengal, India, they discovered that people don’t wash their hands with soap for the same reason most of us don’t run three miles every morning or drink eight glasses of water every day, despite our doctors lecturing us on the benefits of cardiovascular exercise and hydration. It’s not that we are uninformed, unable, or lazy. It’s that we’re just not in the habit.

“The idea is that habits are equivalent to addictions”

With that in mind, the researchers designed a field study to understand whether handwashing with soap was indeed a habit-forming behavior, whether people recognized it as such, whether it was possible to induce the habit with experimental interventions, and whether the habit would continue after the interventions ceased.

The field experiment was based on the theory of “rational addiction.” Developed by economists Gary Becker and Kevin Murphy, the theory posits that addictions are not necessarily irrational. Rather, people often willingly engage in a particular behavior, despite knowing that it will increase their desire to engage in that behavior in the future (i.e. become “addicted”). As “rational addicts,” people can weigh the costs and benefits of their current behavior taking into consideration its implications for the future, and still choose to engage.

One way to test whether people are in fact “rational” about their addictions, Hussam says,is by looking at how changes in the future cost of the behavior affect them today. For example, if a rational addict learns that taxes on cigarettes are going to double in six months, she may be less likely to take up smoking today.

Hussam remains agnostic on whether the behavior of addicts (to cigarettes, drugs, or alcohol, for example) can be fully understood by the theory of rational addiction—“a theory that fails to explain why addicts often regret their behavior or regard it as a mistake,” she says. But she found the framework, which has historically been applied only to harmful behaviors, was useful to shift into the language of positive habits.

“Habits, after all, are like a lesser form of addiction: The more you engage in the past, the more likely you are to engage today,” she says. “And if that’s the case, do people recognize—are they ’rational’ about—the habitual nature of good behaviors? If they aren’t, it could explain the underinvestment in behaviors like handwashing with soap that we see. If they are rational, it can affect the design of interventions and incentives that policymakers can offer to encourage positive habit formation.”

The team’s experiment and findings are detailed in the paper Habit Formation and Rational Addiction: A Field Experiment in Handwashing (pdf), authored by Hussam; Atonu Rabbani, an associate professor at the University of Dhaka; Giovanni Reggiani, then a doctoral student at MIT and now a consultant at The Boston Consulting Group; and Natalia Rigol, a postdoctoral fellow at Harvard’s T.H. Chan School of Public Health.

The hand washing experiment

In partnership with engineers at the MIT Media Lab, the researchers designed a simple wall-mounted soap dispenser with a time-stamped sensor hidden inside. The sensor allowed the team to determine not only how often people were washing their hands, but also whether they were doing so before dinnertime, critical to an effective intervention. (The idea for the hidden sensors came from a scene in Jurassic World in which one of the characters smuggles dinosaur embryos in a jury-rigged can of Barbasol shaving cream.) The data gave the researchers the ability to tease apart behavioral mechanisms in a way that earlier work (which often used self-reports or surveyor observations of hand hygiene) could not do.

The researchers were also mindful about which type of soap to use in the dispensers. Through pilot tests, they found that people preferred foam, for example. “They didn’t feel as clean when the soap wasn’t foamy,” Hussam says.

And because all people in the experiment ate meals with their hands, they were turned off by heavily perfumed soap, which interfered with the taste of their food. So the experiment avoided strongly scented soap. That said, “we preserved some scent, as the olfactory system is a powerful sensory source of both memory and pleasure and thus easily embedded into the habit loop,” the researchers explain in the paper.

The experiment included 3,763 young children and their parents in 2,943 households across 105 villages in the Birbhum District of West Bengal, where women traditionally manage both cooking and childcare. A survey showed that 79 percent of mothers in the sample could articulate, without being prompted, that the purpose of soap is to kill germs.

But while more than 96 percent reported rinsing their hands with water before cooking and eating, only 8 percent said they used soap before cooking and only 14 percent before eating. (Hussam contends that these low numbers are almost certainly overestimates, as they were self-reported.) Some 57 percent of the respondents reported that they didn’t wash their hands with soap simply because “Obhyash nai,” which means “I do not have the habit,” Hussam says.

Monitoring vs. offering incentives

The researchers randomly divided the villages into “monitoring” and “incentive” villages, taking two approaches to inducing the hand washing habit. In each experiment, there was a randomly selected control group of households that did not receive a soap dispenser; altogether, 1,400 of the 2,943 households received dispensers.

“The monitoring experiment tried to understand the beginnings of social norm formation: whether third-party observation through active tracking by surveyors of hand washing behavior could increase hand washing rates, and whether the behavior could become a habit even after the monitoring stopped,” Hussam explains.

Among the 1,400 households that received a soap dispenser, one group was told their hand washing would be tracked from the get-go, and that they would receive feedback reports on their soap usage patterns. Another group was told their behavior would be tracked in a few months, enabling a precise test of rational habit formation—whether people would start washing their hands now if they knew that the “value” of hand washing would increase in the future. And another group was not told that soap use would be tracked.

The incentive experiment “tried to price a household’s value of hand washing and forward-looking behavior,” Hussam says—in other words, whether financial incentives could increase hand washing rates, and whether those households would keep using soap even after the incentives stopped. In one incentive group, people learned that they would receive one ticket for each day they washed their hands; the tickets could be accumulated and cashed in for various goods and gifts in a prize catalog.

In another group, people learned that they initially would receive one ticket each day for washing their hands with soap, but that in two months they would begin receiving triple the number of tickets for every day they used the dispenser. The final group received the same incentive boost two months into the experiment, but it was a happy surprise: The group had no prior knowledge of the triple-ticket future.

“The difference … is a measure of rational habit formation,” Hussam explains. “While one household is anticipating a change in future value of the behavior, the other household is not; if the first household behaves differently than their counterpart in the present, they must recognize that handwashing today increases their own likelihood of handwashing in the future.”

A clean victory

The results showed that both monitoring and monetary incentives led to substantial increases in hand washing with soap.

Households were 23 percent more likely to use soap if they knew they were being monitored. And some 70 percent of ticket-receiving households used their soap dispensers regularly throughout the experiment, compared with 30 percent of households that received the dispensers without incentives.
Importantly, the effects continued even after the households stopped receiving tickets and monitoring reports, suggesting that handwashing with soap was indeed a developable habit.

More importantly, the experiment resulted in healthier children in households that received a soap dispenser, with a 20 percent decrease in acute respiratory infections and a 30 to 40 percent decrease in loose stools on any given day, compared with children whose households did not have soap dispensers. Moreover, the children with soap dispensers ended up weighing more and even growing taller. “For an intervention of only eight months, that really surprised us,” Hussam says.

But while it appeared that handwashing was indeed a habitual behavior, were people “rational” about it? Indeed they were, based on the results of the monitoring experiment.

“Our results are consistent with the key predictions of the rational addiction model, expanding its relevance to settings beyond what are usually considered ‘addictive’ behaviors,” the researchers write.

In the incentives group, the promise of triple tickets didn’t affect behavior much, but, as Hussam notes, that may have been because the single tickets were already enough to get the children their most coveted prize: a school backpack. “Basically, we found that getting one ticket versus getting no tickets had huge effects, while going from one to three did little,” she says.

“Wherever we go, habits define much of what we do”

But in the monitoring group, handwashing rates increased significantly and immediately, not only for those who were monitored but also for those who were simply told to anticipate that their behavior would be tracked at a later date. “Simply knowing that handwashing will be more valuable in the future (because your behavior will be tracked so there’s a higher cost to shirking) makes people wash more today,” Hussam says.

This, Hussam hopes, is the primary takeaway of the study. While the experiment focused on a specific behavior in/among a specific area of India, the findings may prove valuable to anyone who is trying to develop a healthy addiction—whether it be an addiction to treating contaminated drinking water and using mosquito nets in the developing world, or an addiction to exercising every day and flossing every night in the developed world.

“Wherever we go, habits define much of what we do,” Hussam says. “This work can help us understand how to design interventions that help us cultivate the good ones.” 

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