Pest control campaigns • The
Great Hanoi Rat Massacre occurred in 1902, in
Hanoi,
Vietnam (then known as
French Indochina), when, under French colonial rule, the colonial government created a bounty program that paid a reward of 1
¢ for each
rat killed. To collect the bounty, people would need to provide the severed tail of a rat. Colonial officials, however, began noticing rats in Hanoi with no tails. The Vietnamese
rat catchers would capture rats, sever their tails, then release them back into the sewers so that they could produce more rats. • Experiencing an issue with
feral pigs, the
U.S. Army post of
Fort Benning in
Georgia offered hunters a $40-bounty for every pig tail turned in. Over the course of the 2007–2008 program, the feral pig population in the area increased. While there were some reports that individuals purchased pigs' tails from meat processors then resold the tails to the Army at the higher bounty price, a detailed study of the bounty scheme found different effects from perverse incentives were mainly responsible. Both the pigs' fertility rate and offspring survival rates increased under the scheme. This was due to improved nutrition made available by the feed bait used to attract the animals to hunting sites. Secondly, hunters were found to be more likely to preferentially target large males as "trophy"-quality game, while ignoring females and juveniles as targets. Removal of mature males from the population has a negligible impact on population growth, as remaining mature males can each stud many breeding sows.
Community safety and harm reduction • In 2002, British officials tasked with suppressing
opium production in Afghanistan offered
poppy farmers $700 an acre in return for destroying their crop. This ignited a poppy-growing frenzy among Afghan farmers, who sought to plant as many poppies as they could in order to collect payouts from the cash-for-poppies program. Some farmers harvested and sold the sap before destroying the plants, receiving significantly more money for the same amount of poppies. •
Gun buyback programs are carried out by governments to reduce the number of guns in circulation, by purchasing firearms from citizens at a flat rate (and then destroying them). Some residents of areas with gun buyback programs have
3D printed large numbers of crude parts that met the minimum legal definition of a firearm, for the purpose of immediately turning them in for the cash payout. • In 2021, the
US Congress enacted stringent requirements to prevent
sesame, a potential
allergen, from cross-contaminating other foods. Many companies found it simpler and less expensive to instead modify their recipes and add sesame directly to the other foods as an ingredient, and thus avoid being affected by the law. • In
Alberta, under the
Child, Youth and Family Enhancement Act, every person must report suspected
child abuse to a director or police officer, and failure to do so is punishable by a $10,000 fine plus 6 months of imprisonment. However, according to criminal law professor Narayan, enforcing it would cause people to overreport, which wastes resources, and it would also create a
chilling effect that prevents people from reporting child abuse observed over a period of time, as that would incriminate them for failing to report earlier. There are similar laws in other Canadian provinces.
Environmental and wildlife protection • The United States
Endangered Species Act of 1973 imposes development restrictions on landowners who find
endangered species on their property. While this policy has some positive effects for wildlife, it also encourages preemptive
habitat destruction (
draining swamps or cutting down trees that might host valuable species) by landowners who fear losing the lucrative development-friendliness of their land because of the presence of an endangered species. In some cases, endangered species may even be
deliberately killed to avoid discovery. This increased production also caused the price of the refrigerant to decrease significantly, motivating refrigeration companies to continue using it, despite the adverse environmental effects. In 2013, credits for the destruction of HFC-23 were suspended in the
European Union. • In 2017, the Northern Irish
Renewable Heat Incentive paid businesses to replace coal with renewable heating, typically
bioenergy in the form of
wood pellets. However, the subsidy for the energy was greater than its cost, which allowed businesses to make a profit simply by burning as much fuel as possible and heating empty buildings. The political fall-out caused the
Northern Ireland Executive to collapse in 2017. It was not re-convened until 2020.
Historic preservation schemes • The United Kingdom's
listed building regulations are intended to protect historically important buildings, by requiring owners to seek permission before making any changes to listed buildings. In 2017, the owners of an unlisted historic building in Bristol destroyed a 400-year-old ceiling the day before a scheduled visit by listings officers, allegedly to prevent the building from being listed, which could have limited future development. • The
Tax Reform Act of 1976 provided for loss of tax benefits if owners demolished buildings. This led to an increase in
arson attacks in the 1970s as a way of clearing land without financial penalties. The law was later altered to remove this aspect.
Healthcare cost control • Paying
medical professionals and reimbursing insured patients for treatment but not prevention encourages medical conditions to be ignored until treatment is required. Moreover, paying only for treatment effectively discourages prevention (which would improve quality of life for the patient but would also reduce the demand for future treatments). • Payment for treatment generates a perverse incentive for unnecessary treatments. In 2015, a Detroit area doctor was sentenced to 45 years of prison for intentionally giving patients unnecessary cancer treatments, for which health insurance paid him at least 17.6 million dollars. Unnecessary treatment may harm in the form of side effects of drugs and surgery, which can then trigger a demand for further treatments themselves. • In the United States,
Medicare reimburses doctors at a higher rate if they administer more expensive medications to treat a condition. This creates an incentive for the physician to prescribe a more expensive drug when a less expensive one might do.
Humanitarian and welfare policies • In the 2000s, Canada negotiated a "
Safe Third Country Agreement" with the U.S. under which applicants for
political asylum could only apply in the first of the two countries they reached, in order to discourage
asylum shopping. Among the provisions was one that barred anyone entering Canada at an official
port of entry from requesting asylum there, in theory limiting asylum applications to either those filed by refugees in camps abroad or those who could legally travel to Canada and do so at an immigration office. In the late 2010s,
some migrants began entering Canada illegally, between official border crossings, at places like
Roxham Road between New York and Quebec, since once they were in Canada, they were allowed to file applications with the full range of appeals available to them, a process that could take years. Canada wound up processing thousands more applications for asylum than it had planned to. • A
welfare trap is a situation where a person would make less money working (or
working more hours) than they do receiving
state benefits, as a result of
means testing rendering them ineligible for benefits.
Promotional schemes and public relations •
Hacktoberfest is an October-long celebration to promote contributions to the
free and open-source software communities. In 2020, participants were encouraged to submit four or more
pull requests to
any public free or
open-source (FOS) repository, with a free "Hacktoberfest 2020" T-shirt for the first 75,000 participants to do so. The free T-shirts caused frivolous pull requests on FOS projects. • Around 2010, online retailer
Vitaly Borker found that online complaints about his eyeglass-sale website, DecorMyEyes, pushed the site to the top of
Google searches and drove more traffic. He began responding to customer reports of poor quality and/or misfilled orders with insults, threats of violence, and other harassment. Borker continued writing toxic replies for a decade despite serving two separate sentences in U.S. federal prison over charges arising from them.
Returns for effort • The 20th-century
paleontologist G. H. R. von Koenigswald used to pay
Javanese locals for each fragment of
hominin skull that they produced. He later discovered that the people had been breaking up whole skulls into smaller pieces to maximize their payments. When he cancelled the payments, many locals burned the remaining skulls they had as retaliation. • In building the
first transcontinental railroad in the 1860s, the
United States Congress agreed to pay the builders per mile of track laid. As a result,
Thomas C. Durant of
Union Pacific Railroad lengthened a section of the route, forming a bow shape and unnecessarily adding miles of track. • Funding
fire departments by the number of fire calls that are made is intended to reward fire departments that do the most work. However, it may discourage them from
fire-prevention activities, leading to an increase in actual fires.
Electoral systems • An example in
social choice is
perverse response, where a candidate can lose an election if the voters rank them higher. This occurs under
single transferable vote and related systems (like
primary elections and the
two-round system). == In literature ==