Nudge is a concept in behavioral science, political theory and behavioral economics which proposes positive reinforcement and indirect suggestions as ways to influence the behavior and decision making of groups or individuals. Nudging contrasts with other ways to achieve compliance, such as education, legislation or enforcement.
The nudge concept was popularized in the 2008 book Nudge: Improving Decisions About Health, Wealth, and Happiness, by two American scholars at the University of Chicago: economist Richard Thaler and legal scholar Cass Sunstein. It has influenced British and American politicians. Several nudge units exist around the world at the national level (UK, Germany, Japan and others) as well as at the international level (e.g. World Bank, UN, and the European Commission). It is disputed whether “nudge theory” is a recent novel development in behavioral science or merely a new term for one of many methods for influencing behavior, investigated in the science of behavior analysis.
Definition of a nudge
The first formulation of the term and associated principles was developed in cybernetics by James Wilk before 1995 and described by Brunel University academic D. J. Stewart as “the art of the nudge” (sometimes referred to as micronudges). It also drew on methodological influences from clinical psychotherapy tracing back to Gregory Bateson, including contributions from Milton Erickson, Watzlawick, Weakland and Fisch, and Bill O’Hanlon. In this variant, the nudge is a microtargetted design geared towards a specific group of people, irrespective of the scale of intended intervention.
In 2008, Richard Thaler and Cass Sunstein’s book Nudge: Improving Decisions About Health, Wealth, and Happiness brought nudge theory to prominence. It also gained a following among US and UK politicians, in the private sector and in public health. The authors refer to influencing behaviour without coercion as libertarian paternalism and the influencers as choice architects. Thaler and Sunstein defined their concept as:
A nudge, as we will use the term, is any aspect of the choice architecture that alters people’s behavior in a predictable way without forbidding any options or significantly changing their economic incentives. To count as a mere nudge, the intervention must be easy and cheap to avoid. Nudges are not mandates. Putting fruit at eye level counts as a nudge. Banning junk food does not.
In this form, drawing on behavioral economics, the nudge is more generally applied to influence behaviour.
One of the most frequently cited examples of a nudge is the etching of the image of a housefly into the men’s room urinals at Amsterdam’s Schiphol Airport, which is intended to “improve the aim”.
A nudge makes it more likely that an individual will make a particular choice, or behave in a particular way, by altering the environment so that automatic cognitive processes are triggered to favour the desired outcome.
An individual’s behaviour is not always in alignment with their intentions (termed a value-action gap). It is common knowledge that humans are not fully rational beings; that is, people will often do something that is not in their own self interest, even when they are aware that their actions are not in their best interest. As an example, when hungry, people who diet often under-estimate their ability to lose weight, and their intentions to eat healthy can be temporarily weakened until they are satiated.
Nobel Laureate Daniel Kahneman describes two distinct systems for processing information as to why people sometimes act against their own self-interest: System 1 is fast, automatic, and highly susceptible to environmental influences; System 2 processing is slow, reflective, and takes into account explicit goals and intentions. When situations are overly complex or overwhelming for an individual’s cognitive capacity, or when an individual is faced with time-constraints or other pressures, System 1 processing takes over decision-making. System 1 processing relies on various judgmental heuristics to make decisions, resulting in faster decisions. Unfortunately, this can also lead to sub-optimal decisions. In fact, Thaler and Sunstein trace maladaptive behaviour to situations in which System 1 processing over-rides an individual’s explicit values and goals. It is well documented that habitual behaviour is resistant to change without a disruption to the environmental cues that trigger that behaviour.
Nudging techniques aim to use judgmental heuristics to the advantage of the party creating the set of choices. In other words, a nudge alters the environment so that when heuristic, or System 1, decision-making is used, the resulting choice will be the most positive or desired outcome. An example of such a nudge is switching the placement of junk food in a store, so that fruit and other healthy options are located next to the cash register, while junk food is relocated to another part of the store.
Types of nudges
Nudges are small changes in environment that are easy and inexpensive to implement. Several different techniques exist for nudging, including defaults, social proof heuristics, and increasing the salience of the desired option.
A default option is the option an individual automatically receives if he or she does nothing. People are more likely to choose a particular option if it is the default option. For example, Pichert & Katsikopoulos found that a greater number of consumers chose the renewable energy option for electricity when it was offered as the default option.
A social proof heuristic refers to the tendency for individuals to look at the behavior of other people to help guide their own behavior. Studies have found some success in using social proof heuristics to nudge individuals to make healthier food choices.
When an individual’s attention is drawn towards a particular option, that option will become more salient to the individual, and he or she will be more likely to choose to that option. As an example, in snack shops at train stations in the Netherlands, consumers purchased more fruit and healthy snack options when they were relocated next to the cash register. Since then, other similar studies have been made regarding the placement of healthier food options close to the checkout counter and the effect on the consuming behavior of the customers and this is now considered an effective and well-accepted nudge.
Application of theory
In 2008, the United States appointed Sunstein, who helped develop the theory, as administrator of the Office of Information and Regulatory Affairs.
Notable applications of nudge theory include the formation of the British Behavioural Insights Team in 2010. It is often called the “Nudge Unit”, at the British Cabinet Office, headed by David Halpern.
Both Prime Minister David Cameron and President Barack Obama sought to employ nudge theory to advance domestic policy goals during their terms.
In Australia, the government of New South Wales established a Behavioural Insights community of practice.
Nudge theory has also been applied to business management and corporate culture, such as in relation to health, safety and environment (HSE) and human resources. Regarding its application to HSE, one of the primary goals of nudge is to achieve a “zero accident culture”.
Leading Silicon Valley companies are forerunners in applying nudge theory in corporate setting. These companies are using nudges in various forms to increase productivity and happiness of employees. Recently, further companies are gaining interest in using what is called “nudge management” to improve the productivity of their white-collar workers.
Behavioral insights and nudges are currently used in many countries around the world.
Lately, the nudge theory has also been used in different ways to make health care professionals make more deliberate decisions in numerous areas. For example, nudging has been used as a way to improve hand hygiene among health care workers to decrease the number of healthcare associated infections. It has also been used as a way to make fluid administration a more thought-out decision in intensive care units, with the intention of reducing well known complications of fluid overload.
Nudging has also been criticised. Tammy Boyce, from public health foundation The King’s Fund, has said: “We need to move away from short-term, politically motivated initiatives such as the ‘nudging people’ idea, which are not based on any good evidence and don’t help people make long-term behaviour changes.” Likewise, Mols et al (2015) acknowledge nudges may at times be useful, but argue that covert nudges offer limited scope for securing lasting behavior change 
Cass Sunstein has responded to critiques at length in his The Ethics of Influence making the case in favor of nudging against charges that nudges diminish autonomy, threaten dignity, violate liberties, or reduce welfare. He further defended nudge theory in his Why Nudge?: The Politics of Libertarian Paternalism by arguing that choice architecture is inevitable and that some form of paternalism cannot be avoided. Ethicists have debated nudge theory rigorously. These charges have been made by various participants in the debate from Bovens to Goodwin. Wilkinson for example charges nudges for being manipulative, while others such as Yeung question their scientific credibility.
Public opinion on the ethicality of nudges has also been shown to be susceptible to “partisan nudge bias”. Research from David Tannenbaum, Craig R. Fox, and Todd Rogers (2017) found that adults and policymakers in the United States found behavioral policies to be more ethical when they aligned with their own political leanings. Conversely, people found these same mechanisms to be more unethical when they differed from their politics. The researchers also found that nudges are not inherently partisan: when evaluating behavioral policies absent of political cues, people across the political spectrum were alike in their assessments.
Some, such as Hausman & Welch have inquired whether nudging should be permissible on grounds of (distributive) justice; Lepenies & Malecka  have questioned whether nudges are compatible with the rule of law. Similarly, legal scholars have discussed the role of nudges and the law.
Behavioral economists such as Bob Sugden have pointed out that the underlying normative benchmark of nudging is still homo economicus, despite the proponents’ claim to the contrary.
It has been remarked that nudging is also a euphemism for psychological manipulation as practiced in social engineering.
There exists an anticipation and, simultaneously, implicit criticism of the nudge theory in works of Hungarian social psychologists who emphasize the active participation in the nudge of its target (Ferenc Merei), Laszlo Garai).
In their book Neuroliberalism  the authors argue that while there is much value and diversity in behavioural approaches to government there are significant ethical issues, including the danger of the neurological sciences being co-opted to the needs of neo-liberal economics.
- ^“Behavioural Insights”. EU Science Hub. 2015-05-06. Retrieved 28 March 2019.
- ^Tagliabue, Marco; Simon, Carsta (2018). “Feeding the behavioral revolution : Contributions of behavior analysis to nudging and vice versa”. www.semanticscholar.org. Retrieved 2019-06-27.
- ^ Jump up to:ab Mols, F.; Haslam, S. A.; Jetten, J.; Steffens, N. K. (2015). “Why a nudge is not enough: A social identity critique of governance by stealth”. European Journal of Political Research. 54 (1): 81–98. doi:10.1111/1475-6765.12073.
- ^Wilk, J. (1999), “Mind, nature and the emerging science of change: An introduction to metamorphology.”, in G. Cornelis; S. Smets; J. Van Bendegem (eds.), EINSTEIN MEETS MAGRITTE: An Interdisciplinary Reflection on Science, Nature, Art, Human Action and Society: Metadebates on science, 6, Springer Netherlands, pp. 71–87, doi:10.1007/978-94-017-2245-2_6, ISBN 978-90-481-5242-1
- ^O’Hanlon, B.; Wilk, J. (1987), Shifting contexts : The generation of effective psychotherapy., New York, N.Y.: Guilford Press.
- ^See: Dr. Jennifer Lunt and Malcolm Staves
- ^ Jump up to:ab Andrew Sparrow (2008-08-22). “Speak ‘Nudge’: The 10 key phrases from David Cameron’s favorite book”. The Guardian. London. Retrieved 2009-09-09.
- ^Carrasco-Villanueva, Marco (2017-10-18). “Richard Thaler y el auge de la Economía Conductual”. Lucidez (in Spanish). Retrieved 2018-10-31.
- ^ Jump up to:ab Thaler and C. Sunstein. (2008). Nudge. Penguin Books.
- ^ Jump up to:ab c Saghai, Yashar (2013). “Salvaging the concept of nudge”. Journal of Medical Ethics. 39 (8): 487–93. doi:10.1136/medethics-2012-100727. PMID 23427215.
- ^ Jump up to:ab c d Parkinson, J.A.; Eccles, K.E.; Goodman, A. (2014). “Positive impact by design: the Wales centre for behaviour change”. The Journal of Positive Psychology. 9 (6): 517–522. doi:10.1080/17439760.2014.936965.
- ^Kosters, M; Van der Heijden, J (2015). “From mechanism to virtue: evaluating nudge theory”. Evaluation. 21 (3): 276–291. doi:10.1177/1356389015590218. hdl:1885/71637.
- ^Nordgren, L.; Van der Pligt, J.; van Harreveld, F. (2008). “The instability of health cognitions: visceral states influence self-efficacy and related health beliefs”. Health Psychology. 27 (6): 722–727. doi:10.1037/0278-6184.108.40.2062. PMID 19025267.
- ^ Jump up to:ab c d e Campbell-Arvai, V; Arvai, J.; Kalof, L. (2014). “Motivating sustainable food choices: the role of nudges, value orientation, and information provision”. Environment and Behavior. 46 (4): 453–475. doi:10.1177/0013916512469099.
- ^ Jump up to:ab Kroese, F.; Marchiori, D.; de Ridder, D. (2016). “Nudging healthy food choices: a field experiment at the train station”. Journal of Public Health. 38 (2): e133-7. doi:10.1093/pubmed/fdv096. PMID 26186924.
- ^Pichert, D.; Katsikopoulos, K.V. (2008). “Green defaults: information presentation and pro-environmental behavior”. Journal of Environmental Psychology. 28: 63–73. doi:10.1016/j.jenvp.2007.09.004.
- ^Cheung, T.; Kroese, F.; Fennis, B.; de Ridder, D. (2017). “The hunger games: using hunger to promote healthy choices in self-control conflicts”. Appetite. 116: 401–409. doi:10.1016/j.appet.2017.05.020.
- ^Van Gestel, LC (2018). “Nudging at the checkout counter – A longitudinal study of the effect of a food repositioning nudge on healthy food choice”. Psychol Health. 6 (33): 800–809. doi:10.1080/08870446.2017.1416116.
- ^Carol Lewis (2009-07-22). “Why Barack Obama and David Cameron are keen to ‘nudge’ you”. The Times. London. Retrieved 2009-09-09.
- ^James Forsyth (2009-07-16). “Nudge, nudge: meet the Cameroons’ new guru”. The Spectator. Archived from the original on 2009-01-24. Retrieved 2009-09-09.
- ^“About us – Behavioural Insights Team – GOV.UK”. www.gov.uk.
- ^“First Obama, now Cameron embraces ‘nudge theory'”. 12 August 2010.
- ^“What’s new in the Behavioural Insights”. Behavioural Insights. NSW Department of Premier and Cabinet. Archived from the original on 2014-06-16.
- ^“Cast No Shadow” (PDF). Rydermarsh.co.uk. Retrieved 11 October 2017.
- ^Ebert, Philip; Freibichler, Wolfgang (2017). “Nudge management: applying behavioural science to increase knowledge worker productivity”. Journal of Organization Design. 6:4. doi:10.1186/s41469-017-0014-1.
- ^Carrasco-Villanueva, Marco (2016). “中国的环境公共政策：一个行为经济学的选择 [Environmental Public Policies in China: An Opportunity for Behavioral Economics]”. In 上海社会科学院 [Shanghai Academy of Social Sciences] (ed.). 2016上海青年汉学家研修计划论文集 (in Chinese). 中国社会科学出版社 [China Social Sciences Press]. pp. 368–392. ISBN 978-1-234-56789-7.
- ^Caris, MG (2018). “Nudging to improve hand hygiene”. J Hosp Infect. 98 (4): 352–358. doi:10.1016/j.jhin.2017.09.023. PMID 28974467.
- ^Horst, Kawati, Rasmusson, Pikwer, Castegren, Lipscey (2018). “Impact of resuscitation fluid bag size availability on volume of fluid administration in the intensive care unit”. Acta Anaesthesiol Scand. 9 (62): 1261–1266. doi:10.1111/aas.13161. PMID 29851027.
- ^Lakhani, Nina (December 7, 2008). “Unhealthy lifestyles here to stay, in spite of costly campaigns”. The Independent. London. Retrieved April 28, 2010.
- ^Sunstein, Cass R. (2016-08-24). The Ethics of Influence: Government in the Age of Behavioral Science. Cambridge University Press. ISBN 9781107140707.
- ^Schubert, Christian (2015-10-12). “On the Ethics of Public Nudging: Autonomy and Agency”. Rochester, NY. SSRN 2672970.
- ^Sunstein, Cass R. (2014). Why Nudge?: The Politics of Libertarian Paternalism. Yale University Press. ISBN 9780300212693.
- ^Barton, Adrien; Grüne-Yanoff, Till (2015-09-01). “From Libertarian Paternalism to Nudging—and Beyond”. Review of Philosophy and Psychology. 6 (3): 341–359. doi:10.1007/s13164-015-0268-x. ISSN 1878-5158.
- ^Bovens, Luc (2009). “The Ethics of Nudge”. Preference Change. Theory and Decision Library. Springer, Dordrecht. pp. 207–219. doi:10.1007/978-90-481-2593-7_10. ISBN 9789048125920.
- ^Goodwin, Tom (2012-06-01). “Why We Should Reject ‘Nudge'”. Politics. 32 (2): 85–92. doi:10.1111/j.1467-9256.2012.01430.x. ISSN 0263-3957.
- ^Yeung, Karen (2012-01-01). “Nudge as Fudge”. The Modern Law Review. 75 (1): 122–148. doi:10.1111/j.1468-2230.2012.00893.x. ISSN 1468-2230.
- ^ Jump up to:ab c d Tannenbaum, D., Fox, C. R., & Rogers, T. (2017). On the misplaced politics of behavioural policy interventions. Nature Human Behaviour, 1 (10 July 2017), 1-7.
- ^Hausman, Daniel M.; Welch, Brynn (2010-03-01). “Debate: To Nudge or Not to Nudge*”. Journal of Political Philosophy. 18 (1): 123–136. doi:10.1111/j.1467-9760.2009.00351.x. ISSN 1467-9760.
- ^Lepenies, Robert; Małecka, Magdalena (2015-09-01). “The Institutional Consequences of Nudging – Nudges, Politics, and the Law”. Review of Philosophy and Psychology. 6 (3): 427–437. doi:10.1007/s13164-015-0243-6. ISSN 1878-5158.
- ^Alemanno, A.; Spina, A. (2014-04-01). “Nudging legally: On the checks and balances of behavioral regulation”. International Journal of Constitutional Law. 12 (2): 429–456. doi:10.1093/icon/mou033. ISSN 1474-2640.
- ^Kemmerer, Alexandra; Möllers, Christoph; Steinbeis, Maximilian; Wagner, Gerhard (2016-07-15). “Choice Architecture in Democracies: Exploring the Legitimacy of Nudging – Preface”. Rochester, NY. SSRN 2810229.
- ^Sugden, Robert (2017-06-01). “Do people really want to be nudged towards healthy lifestyles?”. International Review of Economics. 64 (2): 113–123. doi:10.1007/s12232-016-0264-1. ISSN 1865-1704.
- ^Cass R. Sunstein. “NUDGING AND CHOICE ARCHITECTURE: ETHICAL CONSIDERATIONS” (PDF). Law.harvard.edu. Retrieved 11 October 2017.
- ^“The Soft Totalitarianism of Nudging”. 13 August 2013.
- ^“A nudge in the right direction? How we can harness behavioural economics”. 1 December 2015.
- ^MÉREI Ferenc (1987): A perem-helyzet egyik változata: a szociálpszichológiai kontúr (A variant of the edge-position: the contour socialpsychological); Pszichológia (1987), 1, pp. 1-5.
- ^Garai L. (2017) The Double-Storied Structure of Social Identity. In: Reconsidering Identity Economics. Palgrave Macmillan, New York
- ^Whitehead, Mark; Jones, Rhys; Lilley, Rachel; Pykett, Jessica; Howell, Rachel (2017). Neuroliberalism. Routledge. ISBN 9781138923829.