KFC keeps its recipe secret. 

It’s stored in a vault in an unknown location. 

Only two KFC executives know the ingredients. 

Neither are allowed to fly on the same plane. 

But this secrecy is illogical. The recipe isn’t important. 

Today on Nudge, Richard Shotton explains how the secrecy makes customers more loyal. 

He shares his favourite ad of all time, and we run one of his experiments on you. 

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Today’s sources: 

Heimbach, J. T., & Jacoby, J. (1972). The Zeigarnik effect in advertising. Advances in Consumer Research: Proceedings of the 3rd Annual Conference of the Association for Consumer Research, 746–757.

Loewenstein, G. (1994). The psychology of curiosity: A review and reinterpretation. Psychological Bulletin, 116(1), 75–98.
Zeigarnik, B. (1927). Über das Behalten von erledigten und unerledigten Handlungen. Psychologische Forschung, 9(1), 1–85.

In 1963, the Milgram experiments revealed something unsettling. 

Most people kept administering what they believed were painful electric shocks, not because they wanted to, but because they couldn’t bring themselves to say no. 

In this episode, my guest shares why we agree to extra projects, unpaid favours and unreasonable requests even when we know we shouldn’t. 

I’m joined by behavioural scientist and physician Dr Sunita Sah of Cornell University. She studies how social pressure and conflict-of-interest disclosures can quietly steer us toward yes.

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Read Sunita’s book Defy: https://amzn.to/48LsreG 

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Today’s sources: 

Milgram, S. (1963). Behavioral study of obedience. Journal of Abnormal and Social Psychology, 67(4), 371–378.

Sah, S. (2025). Defy: The power of no in a world that demands yes. One World.

Sah, S., Loewenstein, G. F., & Cain, D. M. (2013). The burden of disclosure: Increased compliance with distrusted advice. Journal of Personality and Social Psychology, 104(2), 289–304.

Sah, S., Loewenstein, G. F., & Cain, D. M. (2019). Insinuation anxiety: Concern that advice rejection will signal distrust after conflict of interest disclosures. Personality and Social Psychology Bulletin, 45(7), 1099–1112.

Woodzicka, J. A., & LaFrance, M. (2001). Real versus imagined gender harassment. Journal of Social Issues, 57(1), 15–30.

In today’s special end-of-year episode, you’ll hear the best insights from Nudge in 2025.

Hear from Prof. Gerd Gigerenzer, Richard Shotton, Bas Wouters, Philip Graves, Prof. Matt Johnson and a Behavioural Insights Team director. 

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Today’s Sources: 

Beilock, S. L., Bertenthal, B. I., McCoy, A. M., & Carr, T. H. (2004). Haste does not always make waste: Expertise, direction of attention, and speed versus accuracy in performing sensorimotor skills. Psychonomic Bulletin & Review, 11(2), 373–379.

Bellaiche, L., Shahi, R., Turpin, M. H., Ragnhildstveit, A., Sprockett, S., Barr, N., & Seli, P. (2023). Humans versus AI: Whether and why we prefer human-created compared to AI-created artwork. Cognitive Research: Principles and Implications, 8(1), 42.

Groen, J., & Wouters, B. (2020). Online Influence: Boost your results with proven behavioral science. Amazon Digital Services LLC.

Milkman, K. L., Patel, M. S., Gandhi, L., Graci, H. N., Gromet, D. M., Ho, H., Kay, J. S., Lee, T. W., Akinola, M., Beshears, J., Bogard, J. E., Buttenheim, A. M., Chabris, C. F., Chapman, G. B., Duckworth, A. L., Goldstein, N. J., Goren, A., Halpern, S. D., John, L. K., ... & Van den Bulte, C. (2021). A megastudy of text-based nudges encouraging patients to get vaccinated at an upcoming doctor’s appointment. Proceedings of the National Academy of Sciences, 118(20), e2101165118.

Nisbett, R. E., & Wilson, T. D. (1977). Telling more than we can know: Verbal reports on mental processes. Psychological Review, 84(3), 231–259.

van den Broek, E., & den Heijer, T. (2024). The Housefly Effect. Bedford Square Publishers.

Vennard, D., Park, T., & Attwood, S. (2019). Encouraging Sustainable Food Consumption By Using More-Appetizing Language.

How would you encourage Australians to drive slower?

That’s what today’s guest on Nudge, Adam Ferrier, had to do. 

Being an applied behavioural scientist, he tackled this challenge in a novel way. 

Listen to hear about his interesting campaign, how Jaws killed surfing and the secret behind Derren Brown’s “hypnosis” trick. 

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Watch the bonus episode: https://nudge.kit.com/66dcb18641

Adam’s agency: https://thinkerbell.com/

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Today’s sources:

Cialdini, R. B. (1984). Influence: The psychology of persuasion. William Morrow.

Shotton, R. (2023). The illusion of choice: 16½ psychological biases that influence what we buy. Harriman House.

Sutherland, S. (1992). Irrationality: The enemy within. Constable.

Seriously. 

Don’t listen to this episode. 

Whatever you do. 

Don’t.

Press. 

Play.

(Warning: this episode contains explicit language.)

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Adam’s agency: https://thinkerbell.com/

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Today’s sources

Driscoll, R., Davis, K. E., & Lipetz, M. E. (1972). Parental interference and romantic love: The Romeo and Juliet effect. Journal of Personality and Social Psychology, 24(1), 1–10.

Heath, R. (2006). Brand relationships: strengthened by emotion, weakened by attention. Journal of Advertising Research, 46(4), 410–419.

Maimaran, M., & Fishbach, A. (2014). If it’s useful and you know it, do you eat? Preschoolers refrain from instrumental food. Journal of Consumer Research, 41(3), 642–655.

Mazar, N., & Soman, D. (Eds.). (2022). Behavioral science in the wild: Behaviorally informed organizations. University of Toronto Press.

Ryan, R. M. (1982). Control and information in the intrapersonal sphere: An extension of cognitive evaluation theory. Journal of Personality and Social Psychology, 43(3), 450–461.

2 out of 3 internet users in the USA pay for Prime. 

Yet, most of them are irrationally loyal. 

They feel like the subscription provides more cost savings than reality. 

Today, on Nudge, Richard Shotton and I explore the behavioural science behind Amazon Prime. 

We look at the sunk-cost fallacy and pennies-a-day effect to explain why so many are irrationally loyal to Amazon Prime. 

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Today’s sources:

Arkes, H. R., & Blumer, C. (1985). The psychology of sunk cost. Organizational Behavior and Human Decision Processes, 35(1), 124–140.

Gourville, J. T. (1998). Pennies-a-day: The effect of temporal reframing on transaction evaluation. Journal of Consumer Research, 24(4), 395–403.

Gourville, J. T., & Soman, D. (1998). Payment depreciation: The behavioral effects of temporally separating payments from consumption. Journal of Consumer Research, 25(2), 160–174.

Roth, S., Robbert, T., & Straus, L. (2015). On the sunk-cost effect in economic decision-making: A meta-analytic review. Business Research, 8(1), 99–138.

His book Influence sold 5 million times. 

He’s known as the Godfather of Influence. 

He’s arguably the best-known behavioural science practitioner. 

And he’s finally (after years of pestering) joining me on Nudge. 

Ladies and gentlemen, today I present: 

Robert Cialdini and the persuasion principles that EVERYONE should memorise.

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Cialdini’s Influence Unleashed Event: https://cialdini.com/decevent

Unlock the Nudge Vaults: https://www.nudgepodcast.com/vaults

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Read the new and expanded Influence: https://amzn.to/43TY0jI

Read Pre-Suasion: https://amzn.to/48hA6Qr 

Read Yes! (Containing 60 Psyc-Marketing Tips): https://amzn.to/48ddNNf 

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Today’s sources:

Agnew, P. (Host). (2021, November 22). #69: Reciprocity | How one nudge saved 246,184 lives [Audio podcast episode]. In Nudge – Marketing Science Simplified. YouTube. https://youtu.be/0QxcahCnoCs

Cialdini, R. B. (1984). Influence: The psychology of persuasion. HarperCollins.

Cialdini, R. B., Cacioppo, J. T., Bassett, R., & Miller, J. A. (1978). Low-ball procedure for producing compliance: Commitment then cost. Journal of Personality and Social Psychology, 36(5), 463–476.

Deutsch, M., & Gerard, H. B. (1955). A study of normative and informational social influences upon individual judgment. The Journal of Abnormal and Social Psychology, 51(3), 629–636.

Friedman, H. H., & Rahman, A. (2011). The effect of a gift-upon-entry on sales: Reciprocity in a retailing context. International Journal of Business and Social Science, 2(15), 155–162.

Regan, D. T. (1971). Effects of a favor and liking on compliance. Journal of Experimental Social Psychology, 7(6), 627–639.

It’s the most popular cocktail in America. 

But prior to 2015, almost nobody had heard of it. 

So, how did Aperol Spritz become the world’s drink of choice? 

By leveraging a well-known behavioural bias in a totally unique way. 

Join Richard Shotton as he explains why suddenly everyone started drinking Aperol Spritz. 

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Check out the Nudge Vaults: https://www.nudgepodcast.com/vaults

Read Hacking The Human Mind: https://a.co/d/fEW7amQ

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Today’s sources: 

Hallsworth, M., List, J. A., Metcalfe, R. D., & Vlaev, I. (2017). The behavioralist as tax collector: Using natural field experiments to enhance tax compliance. Journal of Public Economics, 148, 14–31.

Keizer, K., Lindenberg, S., & Steg, L. (2008). The spreading of disorder. Science, 322(5908), 1681–1685.

Milne, S., Orbell, S., & Sheeran, P. (2002). Combining motivational and volitional interventions to promote exercise participation: Protection motivation theory and implementation intentions. British Journal of Health Psychology, 7(2), 163–184.

von Restorff, H. (1933). Über die Wirkung von Bereichsbildungen im Spurenfeld. Psychologische Forschung, 18(1), 299–342.

My guest on today’s episode of Nudge has spent decades studying leaders. 

I asked Prof. Adam Galinsky to share his top five (evidence-backed) leadership tips. 

Want to become a better leader? 

This is the episode for you. 

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Watch the bonus episode: https://nudge.kit.com/a53ff22931 

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Blunden, H., Kristal, A. S., Whillans, A. V., Yoon, J., Burd, K., Bremner, S., & Yeomans, M. (2025). Eliciting advice instead of feedback improves developmental input. Organizational Behavior and Human Decision Processes, 193, 104343.

Chou, E. Y., Halevy, N., Galinsky, A. D., & Murnighan, J. K. (2017). The Goldilocks contract: The synergistic benefits of combining structure and autonomy for persistence, creativity, and cooperation. Journal of Personality and Social Psychology, 113(3), 393–412.

Hoff, M., Rucker, D. D., & Galinsky, A. D. (2025). The vicious cycle of status insecurity. Journal of Personality and Social Psychology, 128(1), 101–122.

Leonardelli, G. J., Gu, J., McRuer, G., Medvec, V. H., & Galinsky, A. D. (2019). Multiple equivalent simultaneous offers (MESOs) reduce the negotiator dilemma: How a choice of first offers increases economic and relational outcomes. Organizational Behavior and Human Decision Processes, 152, 64–82.

Liljenquist, K. A., & Galinsky, A. D. (2007). Turn your adversary into your advocate: Strategic requests for advice can transform disputes into amiable problem-solving ventures. Kellogg Insight. Northwestern University.

Majer, J. M., Trötschel, R., Galinsky, A. D., & Loschelder, D. D. (2020). Open to offers, but resisting requests: How the framing of anchors affects motivation and negotiated outcomes. Journal of Personality and Social Psychology, 119(3), 582–599.

Wu, S. J., & Paluck, E. L. (2022). Having a voice in your group: Increasing productivity through group participation. Behavioural Public Policy, 9(1), 192–211.

In 1989, The Simpsons released Itchy & Scratchy & Marge. 

It’s a classic Simpson’s episode filled with slapstick humour, dry jokes, and smart gags. 

And yet, behind all the humour, there’s an important lesson about leadership. 

Today, Chief Behavioural Scientist Micheal Hallsworth explains what Marge Simpson can teach you about leadership.  

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Today’s sources: 

Barrick, E. M., Barasch, A., & Tamir, D. I. (2022). The unexpected social consequences of diverting attention to our phones. Journal of Experimental Social Psychology, 101, Article 104344.

Jordan, J. J., Sommers, R., Bloom, P., & Rand, D. G. (2017). Why do we hate hypocrites? Evidence for a theory of false signaling. Psychological Science.

Thomas, O., & Reimann, O. (2023). The bias blind spot among HR employees in hiring decisions. German Journal of Human Resource Management, 37(1), 5–22.

Tokunaga, R. S. (2010). Following you home from school: A critical review and synthesis of research on cyberbullying victimization. Computers in Human Behavior, 26(3), 277–287

Are inspiring leaders born or are they made? 

That’s what Adam Galinsky, the Columbia Business School professor, has spent the past two decades studying inspiring leaders. 

On today’s episode of Nudge, he shares his groundbreaking research into inspiration, reciprocity, repetition and visionary statements that reshaped how I saw leadership. 

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Today’s sources: 

Begg, I. (1972). Recall of meaningful phrases. Journal of Verbal Learning and Verbal Behavior, 11(4), 431–439.

Cabinet Office & Behavioural Insights Team. (2013, May 28). Applying behavioural insights to charitable giving. Behavioural Insights Team. https://www.gov.uk/government/publications/applying-behavioural-insights-to-charitable-giving

Carton, A. M., Murphy, C., & Clark, J. R. (2014). A (blurry) vision of the future: How leader rhetoric about ultimate goals influences performance. Academy of Management Journal, 57(6), 1544–1570.

Cialdini, R. B. (1984). Influence: The psychology of persuasion. William Morrow & Company.

Liu, J., Hong, X., Zheng, Z., & Zhong, J. (2023). When consumers have difficulty understanding ads: How technical language lowers purchase intention. Journal of Consumer Behaviour, 22(6), 1550–1563.