Editing Trolley problem (section)

== Empirical research ==
{{See also|Moral psychology|Dual process theory (moral psychology)}}
In 2001, [[Joshua Greene (psychologist)|Joshua Greene]] and colleagues published the results of the first significant empirical investigation of people's responses to trolley problems.<ref>{{Cite journal|last1=Greene|first1=Joshua D.|last2=Sommerville|first2=R. Brian|last3=Nystrom|first3=Leigh E.|last4=Darley|first4=John M.|last5=Cohen|first5=Jonathan D.|date=2001-09-14|title=An fMRI Investigation of Emotional Engagement in Moral Judgment|journal=Science|language=en|volume=293|issue=5537|pages=2105–2108|doi=10.1126/science.1062872|issn=0036-8075|pmid=11557895|bibcode=2001Sci...293.2105G|s2cid=1437941}}</ref> Using [[functional magnetic resonance imaging]], they demonstrated that "personal" dilemmas (like pushing a man off a footbridge) preferentially engage brain regions associated with emotion, whereas "impersonal" dilemmas (like diverting the trolley by flipping a switch) preferentially engaged regions associated with controlled reasoning. On these grounds, they advocate for the [[Dual process theory (moral psychology)|dual-process account of moral decision-making]]. Since then, numerous other studies have employed trolley problems to study moral judgment, investigating topics like the role and influence of stress,<ref>{{Cite journal|last1=Youssef|first1=Farid F.|last2=Dookeeram|first2=Karine|last3=Basdeo|first3=Vasant|last4=Francis|first4=Emmanuel|last5=Doman|first5=Mekaeel|last6=Mamed|first6=Danielle|last7=Maloo|first7=Stefan|last8=Degannes|first8=Joel|last9=Dobo|first9=Linda|title=Stress alters personal moral decision making|journal=Psychoneuroendocrinology|volume=37|issue=4|pages=491–498|doi=10.1016/j.psyneuen.2011.07.017|pmid=21899956|year=2012|s2cid=30489504}}</ref> emotional state,<ref>{{Cite journal|last1=Valdesolo|first1=Piercarlo|last2=DeSteno|first2=David|date=2006-06-01|title=Manipulations of Emotional Context Shape Moral Judgment|journal=Psychological Science|language=en|volume=17|issue=6|pages=476–477|doi=10.1111/j.1467-9280.2006.01731.x|issn=0956-7976|pmid=16771796|s2cid=13511311}}</ref> impression management,<ref>{{Cite journal|last=Rom, Sarah C.|first=Paul, Conway|date=2017-08-30|title=The strategic moral self:self-presentation shapes moral dilemma judgments|journal=Journal of Experimental Social Psychology|language=en|volume=74|pages=24–37|doi=10.1016/j.jesp.2017.08.003|s2cid=52205265 |issn=0022-1031|url=http://purl.flvc.org/fsu/fd/FSU_libsubv1_wos_000418989800003}}</ref> levels of anonymity,<ref>{{Cite journal|first1=Minwoo|last1=Lee|first2=Sunhae|last2=Sul|first3=Hackjin|last3=Kim|date=2018-06-18|title=Social observation increases deontological judgments in moral dilemmas|journal=Evolution and Human Behavior|volume=39|issue=6|pages=611–621|doi=10.1016/j.evolhumbehav.2018.06.004|s2cid=150247068|issn=1090-5138}}</ref> different types of brain damage,<ref>{{Cite journal|last1=Ciaramelli|first1=Elisa|last2=Muccioli|first2=Michela|last3=Làdavas|first3=Elisabetta|last4=Pellegrino|first4=Giuseppe di|date=2007-06-01|title=Selective deficit in personal moral judgment following damage to ventromedial prefrontal cortex|journal=Social Cognitive and Affective Neuroscience|language=en|volume=2|issue=2|pages=84–92|doi=10.1093/scan/nsm001|issn=1749-5024|pmc=2555449|pmid=18985127}}</ref> physiological arousal,<ref>{{Cite journal|last1=Navarrete|first1=C. David|last2=McDonald|first2=Melissa M.|last3=Mott|first3=Michael L.|last4=Asher|first4=Benjamin|date=2012-04-01|title=Virtual morality: Emotion and action in a simulated three-dimensional "trolley problem".|journal=Emotion|language=en|volume=12|issue=2|pages=364–370|doi=10.1037/a0025561|pmid=22103331|s2cid=34621870 |issn=1931-1516}}</ref> different neurotransmitters,<ref>{{Cite journal|last1=Crockett|first1=Molly J.|last2=Clark|first2=Luke|last3=Hauser|first3=Marc D.|last4=Robbins|first4=Trevor W.|date=2010-10-05|title=Serotonin selectively influences moral judgment and behavior through effects on harm aversion|journal=Proceedings of the National Academy of Sciences|language=en|volume=107|issue=40|pages=17433–17438|doi=10.1073/pnas.1009396107|issn=0027-8424|pmc=2951447|pmid=20876101|bibcode=2010PNAS..10717433C|doi-access=free}}</ref> and genetic factors<ref>{{Cite journal|last1=Bernhard|first1=Regan M.|last2=Chaponis|first2=Jonathan|last3=Siburian|first3=Richie|last4=Gallagher|first4=Patience|last5=Ransohoff|first5=Katherine|last6=Wikler|first6=Daniel|last7=Perlis|first7=Roy H.|last8=Greene|first8=Joshua D.|date=2016-12-01|title=Variation in the oxytocin receptor gene (OXTR) is associated with differences in moral judgment|journal=Social Cognitive and Affective Neuroscience|language=en|volume=11|issue=12|pages=1872–1881|doi=10.1093/scan/nsw103|issn=1749-5016|pmc=5141955|pmid=27497314}}</ref> on responses to trolley dilemmas.

Trolley problems have been used as a measure of utilitarianism, but their usefulness for such purposes has been widely [[#Criticism|criticized]].<ref name="Bauman2014" /><ref name="Kahane2018" /><ref name="Kahane2015">{{cite journal |last1=Kahane |first1=Guy |title=Sidetracked by trolleys: Why sacrificial moral dilemmas tell us little (or nothing) about utilitarian judgment |journal=Social Neuroscience |date=20 March 2015 |volume=10 |issue=5 |pages=551–560 |doi=10.1080/17470919.2015.1023400|pmid=25791902 |pmc=4642180 |doi-access=free }}</ref>

In 2017, a group led by [[Michael Stevens (educator)|Michael Stevens]] performed the first realistic trolley-problem experiment, where subjects were placed alone in what they thought was a train-switching station, and shown footage that they thought was real (but was actually prerecorded) of a train going down a track, with five workers on the main track, and one on the secondary track; the participants had the option to pull the lever to divert the train toward the secondary track. Five of the seven participants did not pull the lever.<ref name="VSauce">{{cite episode|url=https://www.youtube.com/watch?v=1sl5KJ69qiA |archive-url=https://ghostarchive.org/varchive/youtube/20211212/1sl5KJ69qiA| archive-date=2021-12-12 |url-status=live|title=The Greater Good|series=Mind Field|season=2|number=1|last=Stevens|first=Michael |author-link=Michael Stevens (educator)|date=6 December 2017|access-date=23 December 2018}}{{cbignore}}</ref><ref>{{cite web | url=https://www.iflscience.com/a-youtuber-recreated-the-trolley-problem-in-real-life-73524 | title=A YouTuber Recreated The Trolley Problem In Real Life | author= | website=IFLScience | date=2023-01-20 | accessdate=2025-04-25}}</ref>

=== Survey data ===
The trolley problem has been the subject of many surveys in which about 90% of respondents have chosen to kill the one and save the five.<ref>{{cite magazine|url=https://healthland.time.com/2011/12/05/would-you-kill-one-person-to-save-five-new-research-on-a-classic-debate/|title='Trolley Problem': Virtual-Reality Test for Moral Dilemma – TIME.com|magazine=[[Time (magazine)|Time]]}}</ref> If the situation is modified where the one sacrificed for the five was a relative or romantic partner, respondents are much less likely to be willing to sacrifice the one life.<ref>{{cite journal |author=April Bleske-Rechek |author2=Lyndsay A. Nelson |author3=Jonathan P. Baker |author4=Mark W. Remiker |author5=Sarah J. Brandt|title=Evolution and the trolley problem: People save five over one unless the one is young, genetically related, or a romantic partner |url=http://137.140.1.71/jsec/articles/volume4/issue3/bleskefinal.pdf |journal=Journal of Social, Evolutionary, and Cultural Psychology |archive-url=https://web.archive.org/web/20120411182922/http://137.140.1.71/jsec/articles/volume4/issue3/bleskefinal.pdf |volume=4 |issue=3 |pages=115–127 |year=2010|doi=10.1037/h0099295 |archive-date=2012-04-11 }}</ref>

A 2009 survey by David Bourget and [[David Chalmers]] shows that 68% of professional philosophers would switch (sacrifice the one individual to save five lives) in the case of the trolley problem,  8% would not switch, and the remaining 24% had another view or could not answer.<ref>{{cite web|last1=Bourget|first1=David|last2=Chalmers|first2=David J.|year=2013|title=What do Philosophers believe?|url=http://philpapers.org/archive/BOUWDP|access-date=11 May 2013}}</ref>

=== Criticism ===
In a 2014 paper published in the ''Social and Personality Psychology Compass'',<ref name="Bauman2014">{{cite journal|last1=Bauman|first1=Christopher W.|last2=McGraw|first2=A. Peter|last3=Bartels|first3=Daniel M.|last4=Warren|first4=Caleb|title=Revisiting External Validity: Concerns about Trolley Problems and Other Sacrificial Dilemmas in Moral Psychology|date=September 4, 2014|journal=Social and Personality Psychology Compass|volume = 8|issue=9|pages=536–554|doi=10.1111/spc3.12131|s2cid=11170070 |url=http://www.escholarship.org/uc/item/5j0215cr}}</ref> researchers criticized the use of the trolley problem, arguing, among other things, that the scenario it presents is too extreme and unconnected to real-life moral situations to be useful or educational.<ref>{{cite web|url=https://www.theatlantic.com/health/archive/2014/07/what-if-one-of-the-most-popular-experiments-in-psychology-is-worthless/374931/|title=Is One of the Most Popular Psychology Experiments Worthless?|last=Khazan|first=Olga|date=July 24, 2014|work=[[The Atlantic]]}}</ref>

In her 2017 paper, Nassim JafariNaimi<ref>{{Cite journal|title=Our Bodies in the Trolley's Path, or Why Self-driving Cars Must *Not* Be Programmed to Kill|journal = Science, Technology, & Human Values|volume = 43|issue = 2|pages = 302–323|last=JafariNaimi|first=Nassim|doi=10.1177/0162243917718942|year = 2018|s2cid = 148793137}}</ref> lays out the reductive nature of the trolley problem in framing ethical problems that serves to uphold an impoverished version of utilitarianism. She argues that the popular argument that the trolley problem can serve as a template for algorithmic morality is based on fundamentally flawed premises that serve the most powerful with potentially dire consequences on the future of cities.<ref>{{cite news |title=Why Self-Driving Cars Must Be Programmed to Kill |url=https://www.technologyreview.com/s/542626/why-self-driving-cars-must-be-programmed-to-kill/ |work=MIT Technology Review |date=October 22, 2015 |language=en}}</ref>

In 2017, in his book ''On Human Nature'', [[Roger Scruton]] criticises the usage of ethical dilemmas such as the trolley problem and their usage by philosophers such as [[Derek Parfit]] and [[Peter Singer]] as ways of illustrating their ethical views. Scruton writes, "These 'dilemmas' have the useful character of eliminating from the situation just about every morally relevant relationship and reducing the problem to one of arithmetic alone." Scruton believes that just because one would choose to change the track so that the train hits the one person instead of the five does not mean that they are necessarily a [[consequentialist]]. As a way of showing the flaws in consequentialist responses to ethical problems, Scruton points out paradoxical elements of belief in utilitarianism and similar beliefs. He believes that [[Robert Nozick|Nozick's]] [[experience machine]] thought experiment definitively disproves [[hedonism]].<ref>{{cite book |last=Scruton |first=Roger |author-link=Roger Scruton |title=On Human Nature |publisher=Princeton |edition=1st |date=2017 |pages=79–112 |isbn=978-0-691-18303-9}}</ref> In his 2017 article ''The Trolley Problem and the Dropping of Atomic Bombs,'' Masahiro Morioka considers the dropping of atomic bombs as an example of the trolley problem and points out that there are five "problems of the trolley problem", namely, 1) rarity, 2) inevitability, 3) safety zone, 4) possibility of becoming a victim, and 5) the lack of perspective of the dead victims who were deprived of freedom of choice.<ref>{{Cite web|url=https://www.bbc.com/future/article/20200804-can-nuclear-war-ever-be-morally-justified|title=Can nuclear war be morally justified?|first=Richard|last=Fisher|website=www.bbc.com|accessdate=19 April 2023}}; {{Cite journal|title=The Trolley Problem and the Dropping of Atomic Bombs |journal=Journal of Philosophy of Life |date=2017 |volume=7 |issue=2 |pages=316–337 |url=https://philarchive.org/rec/MORTTP-7 |last1=Morioka |first1=Masahiro }}</ref>

In a 2018 article published in ''Psychological Review'', researchers pointed out that, as measures of utilitarian decisions, sacrificial dilemmas such as the trolley problem measure only one facet of proto-utilitarian tendencies, namely permissive attitudes toward instrumental harm, while ignoring impartial concern for the greater good. As such, the authors argued that the trolley problem provides only a partial measure of utilitarianism.<ref name="Kahane2018">{{cite journal |last1=Kahane |first1=Guy |last2=Everett |first2=Jim A. C. |last3=Earp |first3=Brian D. |last4=Caviola |first4=Lucius |last5=Faber |first5=Nadira S. |last6=Crockett |first6=Molly J. |last7=Savulescu |first7=Julian |title=Beyond sacrificial harm: A two-dimensional model of utilitarian psychology. |journal=Psychological Review |date=March 2018 |volume=125 |issue=2 |pages=131–164 |doi=10.1037/rev0000093|pmid=29265854 |pmc=5900580 }}</ref>