Business Daily (BBC World Service)

Episode: Why you buy what you buy

Air date: January 29, 2026
Host: Rowan Bridge

Episode Overview

This episode of Business Daily delves into the fascinating world of behavioral science and how it invisibly influences the choices we make as consumers and citizens. Host Rowan Bridge explores how companies, governments, and organizations—from toothpaste brands to the United Nations—use scientific insights to nudge our behavior, often without us even realizing it. The episode features interviews and anecdotes from leaders in marketing, academia, government, and behavioral policy, illustrating how subtle cues, habit triggers, and the “hidden hand” of psychology shape everyday decisions.

Key Discussion Points & Insights

The Science Behind Our Choices

• Behavioral Science’s Ancient Roots
  • Rory Sutherland (Ogilvy vice chairman) explains that the concepts underpinning behavioral science are ancient, citing examples from the Bible and Aesop’s Fables that illustrate principles like loss aversion and human bias.

    "Undoubtedly, one of the first behavioral scientists worthy of the name was Aesop himself." – Rory Sutherland (02:58)

Authority Bias: Who Tells Us What Works?

• Endorsements Through Authority
  • The episode opens by dissecting why advertisements featuring authority figures (doctors, athletes, etc.) influence us so powerfully.
  • Ben Jones (Behavior Architects) defines authority bias:

    "The authority bias is the tendency we have to align our opinions or our behaviors with someone we see as an authority or an expert." – Ben Jones (01:33, 04:39)

  • Historical context: 1940s Camel cigarettes used doctors in ads; today’s toothpaste brands still feature dentists.

Self-Service Terminals and the Judgment Factor

• The Psychology of Ordering Fast Food
  • Dean Ward (Evoke Creative) describes how self-service screens at places like McDonald's encourage higher spending:

    "You're very much more inclined to actually say yes to these things ... an increased basket spend of typically 25, 30%." – Dean Ward (06:06)

  • Removing potential judgement from human cashiers allows customers to confidently opt for upsells and larger portions.

How Our Senses Fool Us: The Case of Chocolate and Wine

• Shape and Taste Associations
  • Charles Spence (Oxford University) discusses experimental findings mapping taste sensations to shapes, influencing product design.

    "Sweet is round, bitter is more angular." – Charles Spence (07:10)

• The Music in the Wine Aisle
  • A landmark study demonstrated that French or German music subtly influenced wine purchases; few realized they were influenced.

    "Virtually nobody was aware that ... the music was having an effect." – Charles Spence (08:18)

Governments and Behavioral Interventions: The Power of Nudges

• Cass Sunstein and Nudge Theory
  • Cass Sunstein (Harvard/Obama Admin), co-author of "Nudge," describes how policy design can use human tendencies to maximize outcomes (e.g., automatically enrolling eligible students in free school meals).

    "Kids who are eligible and known to be eligible are automatically enrolled in that program. And that ... has been serving millions of children." – Cass Sunstein (10:04)

• Default Bias and Pensions
  • Changing retirement plan enrollment from opt-in to opt-out (“default bias”) dramatically increases participation.

    "Generally, it’s our tendency to go with the option that’s already selected..." – Ben Jones (12:46)

Nudge in Practice: The Plastic Bag Tax

• Social Norms and Consumer Behavior
  • Rory Stewart (former minister): The 5p plastic bag charge in England reduced usage by 98%—a direct application of behavioral insights around social norms and penalties.

    "It had much bigger impact, reduced the number of bags much more quickly than we expected and did so with none of the worst case scenarios." – Rory Stewart (15:26)

  • Initial political and public opposition was strong, but the eventual success turned critics around.

Digital Nudges: COVID Vaccines via WhatsApp

• Implementation Intentions and Messenger Effects
  • The UK’s Behavioral Insights Team (now a global advisory group) used WhatsApp chatbots in Argentina to promote COVID vaccine boosters.
  • Tactics included prompts for concrete planning and leveraging a beloved pop singer ("La Mosca") to deliver the message, quadrupling booster uptake (0.35% to 1.44%).

    "So the third version had the personalization implementation intentions, the vaccine locator and then the additional messenger effect of La Moska—take up quadrupled." – Monica Willis Silver (16:56)

Edutainment Nudges: Behavioral Change Through TV

• UN World Food Program in Tunisia
  • The show "Sala Sala" used drama to encourage family meals and reduce bread waste.

    "Facts only doesn't change ... people and doesn't change behavior. We all know better, but we don't do better." – Taqwa Khalifi (18:44)

  • Results: 1/3 of families ate together more; bread consumption dropped 22%.

Limits and Political Realities

• Scaling and Resistance
  • Not every nudge produces massive change—small movement at scale can have a significant impact.

    "Changing the default from opt in to opt out often has a very large effect ... but across a large population ... that can mean a certain number of people don’t die ... hooray for that." – Cass Sunstein (20:25)

• Policy Pushback
  • Rory Stewart: Efforts to expand behavioral taxes (e.g., for coffee cups) ran into political and industry resistance.

    "I was now looking at it and this was the moment which I got called by Liz Truss and number 10 and everyone said enough already, stop, shut up, don't continue down this track." – Rory Stewart (21:07)

Memorable Moments & Quotes

• Behavioral science’s ancient history:

  "Aesop ... one of the first behavioral scientists worthy of the name." – Rory Sutherland (02:58)

• Music in wine aisles:

  "Virtually nobody was aware that ... the music was having an effect." – Charles Spence (08:18)

• Default bias in everyday life:

  "If you have an iPhone ... your ringtone is this. That's the default..." – Rowan Bridge (12:21)

• Limitations/realities of nudges:

  "It’s not ... going to transform humanity, but hooray for that." – Cass Sunstein (20:25)

Timestamps for Key Segments

• Authority bias in advertising: 01:33 – 04:39
• How self-service kiosks increase spending: 05:24 – 06:43
• Shape influences taste perception: 06:54 – 08:03
• Music influencing wine selection: 08:18 – 09:10
• Nudge theory and government policy (Sunstein): 10:04 – 11:48
• Default bias and pensions: 12:21 – 13:08
• Plastic bag tax in England—case study: 13:17 – 15:26
• WhatsApp nudging for COVID vaccines: 16:26 – 17:57
• Behavior change through TV drama: 18:44 – 19:57
• Reflections and limits of behavioral science: 20:25 – 21:54

Conclusion

The world is full of invisible signals and "nudges" designed to influence what you buy and do—from authority figures in adverts, to the default options on your phone, to subtle environmental cues in stores, and even the plotlines of TV shows. Behavioral science, once the realm of academic curiosity, now shapes everything from marketing tactics to government policy—often to our benefit, but sometimes meeting resistance or falling short of transformation. As Rowan Bridge concludes, being aware of these influences helps us better understand our choices—and perhaps even reclaim a bit more agency over the daily drama of money and work.