Many of you have likely followed the recent outbreak of measles, now reported by the CDC to include cases in fourteen states. The outbreak surfaces so many interesting issues –medical ethics, societal obligations, personal choice and political implications, but the most illuminating angle to understanding the outbreak might be behavioral science.
The reluctance of many parents today to have their children vaccinated is a textbook case of the Availability Heuristic. This mental shortcut was first proposed by behavioral scientists Amos Tversky and Daniel Kahneman in the 1970s. The basic idea is that when individuals gauge the probability that any event will occur, say for instance that their child’s health could be threatened by a measles outbreak, they are likely to be biased by the information that is most readily available to them. That is, most people will not necessarily seek outside data or statistics to come to a conclusion, but instead rely on their own experiences.
The lens of the availability heuristic makes it less surprising that so many parents in recent years have chosen not to have their children vaccinated. Most people have never seen anyone with the measles, much less known anyone to be seriously ill with them. Other diseases such as whooping cough and rubella have become so rare in western society as to no longer be considered a real threat. And while these remain dangerous and highly contagious diseases, they’re not something most parents of young children in the U.S. today have actually experienced themselves. So while detailed health data is more available than ever, if we rely on direct experiences when making judgments, especially the most vivid and recent ones, we will likely come to the wrong conclusions on the risks of avoiding vaccinations.
We see the availability heuristic at work in many other fields, including water. In an excellent 2014 study by Shahzeen Attari of Indiana University, individuals were asked what actions they could take to most effectively save water in their own lives. The top three answers - by far - were taking shorter showers, turning off water while brushing teeth, and turning off water during other tasks. While it’s not surprising that these activities were easy for individuals to recall having likely showered and brushed their teeth at least once that day, these are actually some of the least effective water saving actions. Showering accounts for only about 10% of water use in the home. Outdoor irrigation, on the other hand, uses an average of 30% of municipal water use, but only 4% of individuals cited watering the lawn less compared to the 40% that cited shorter showers. Irrigation is outside –literally out of sight, and consequently out of mind.
The availability heuristic is luckily not an incurable bias. For better or worse, the current measles outbreak is likely to change the perception of many young parents, making the possibility of contracting the disease a more vivid possibility that changes their mental assessment of vaccines. Better information can help in water too. One of WaterSmart’s insights is to clearly communicate how much water is being used by a home (in Gallons Per Day – a unit that is easily understood by any resident), and helping households understand how that water is likely being used. When a resident sees they use 500 gallons per day they may not believe it -- their showers, toilets, dishwasher, and cooking just don’t add up to that –- but a simple pie chart showing a large slice of water going to outdoor use may change things. They may, in fact, even go look at the irrigation controller and see how many hundreds of gallons it may be using per day. When asked to reduce by their water utility they may shorten their shower, but they may also more easily recall to check their watering schedule. The power of behavioral science!