The one sentence summary

There are at least 25 behavioural biases that influence what we buy.


  1. The Fundamental Attribution Error. Those in a rush are distracted, so brands need to target contexts as much as audiences.
  2. Social Proof. Popular brands become even more popular because their visibility provides social proof. Don’t assume your scale is known.
  3. Negative Social Proof. Don’t confirm inferiority (“Only a tiny proportion of our readers give.”) Flip the statistics in your favour.
  4. When the world zigs, zag. Subvert category norms.
  5. Most behaviour is habitual, so aim to shake people out of such behaviour, and target them after they have undergone a life event.
  6. The Pain of Payment. Handing over money hurts. People using cash overestimate their spend by 9%, so invest in cashless payment technology, and remove the £ signs from your price lists.
  7. The Danger of Claimed Data. People lie in research, or at least can’t be accurate. Be prepared for deceit and design surveys accordingly.
  8. Mood. Target customers when they are likely to be happy, and match the message to their mood.
  9. Price Relativity. Make your brand appear better value by changing the comparison set. Introduce a higher end line to set a new comparison level.
  10. Primacy Effect. First impressions shape subsequent experiences, so make yours as strong as possible.
  11. Expectancy Theory. Expectations of a product shape its performance. Good copywriting is therefore like a china plate. It makes products taste better.
  12. Confirmation Bias. Don’t target those likely or unlikely to buy regardless of communications. Go for those for whom it might make a difference.
  13. Overconfidence. This affects marketers and customers alike. If you have an above average campaign, leave it alone.
  14. Wishful Seeing. What we see is sometimes what we want to see. Don’t assume that a brand purpose will solve your marketing problems.
  15. Media Context. The placement of an ad affects its interpretation.
  16. The Curse of Knowledge. We struggle to empathise because we are not very good listeners. You need to think like a customer.
  17. Goodhart’s Law. States that when a measure becomes a target, it ceases to be a good measure.
  18. The Pratfall Effect. Someone who stumbles or is clumsy is more appealing because they become more approachable. Flaws make brands more appealing.
  19. Winner’s Curse. Payday spend spikes by 70%. Advertisers often overpay because they outbid others.
  20. The Power of the Group. Targeting groups boosts effectiveness. It’s like canned laughter – groups respond more than individuals.
  21. Veblen Goods*. High price can boost demand, counter to what economists would predict. And promotions are like bad cholesterol.
  22. The Replicability Crisis. Much market research doesn’t generate the same results when done again, so don’t take a single study as definitive proof. Be sceptical, but not cynical.
  23. Variability. A bias that works in one situation might backfire in another, so using nudges is a constant work of refinement.
  24. Cocktail Party Effect. You tend to hear your own name mentioned at a loud party – that’s the power of personalisation, and the media landscape is like a packed pub. Think “Your country needs you” rather than “The British army is short of 2 million new recruits.”
  25. Scarcity. The less there is, the more people want it, so restricting the number of items can boost sales.

*Named after the American economist who identified the phenomenon, although the book doesn’t mention this.