I've just spent two days traveling from London to Valencia by train.
Over the 48 hours, I saw a lot of crap messaging.
The worst offender = Valencia tram ticket machine.
Look at the image and ask yourself, how do I activate my ticket?
A day later, I discovered it's the big red circle to the left.
I believe that almost every message could be improved by behavioural science.
I've collected six successful messages with BS principles behind them to prove my point.
Anchoring — De Beers
In the 1930s, only 10% of Americans bought diamond engagement rings.
Most spent a smaller proportion of their disposable income on cheaper gems.
So, to break the habit, De Beers came up with a new anchor.
They said, "How can you make two months' salary last forever?".
Hardly anyone spent two months' salary on an engagement ring before this.
But this new anchor shifted perception.
Today, 90% of engagement rings are diamond.
Pratfall Effect — Avis
Rental car company Avis always lagged 2nd for market share behind Hertz.
Most companies would hide this weakness, but Avis embraced it.
Aronson's 1966¹ study found that we like smart people more if they have flaws.
So, Avis took this to heart and flaunted their weakness.
Generation Effect — Gut Check
There's a straightforward way to get someone to notice your ad.
Remove a letter.
In 2020, researchers² showed participants brand names with missing letters.
H_BC, Goo_e, Li_erpool FC, N_dge.
It turns out that participants remember those brand names 14% more than entirely written brands (e.g., HSBC), with a recall rate of 92% versus 81%.
The Gut Foundation applied this to their ads.
They didn't tell drivers to get checked. They advertised 100% "anus beef".
The purposeful typo forced drivers to pay attention.
Keats Heuristic — Tesco
Rhymes are potent messaging tools.
Researchers McGlone and Tofighbakhsh³ showed participants two sets of proverbs.
Some rhymed; e.g. Woes unite foes.
Some didn't rhyme (but meant the same thing); e.g. Woes unite enemies.
The study revealed that rhyming proverbs were deemed 17% more trustworthy and memorable than their non-rhyming counterparts.
Tesco use the same principle to boost sales of its reduced veg.
A message that rhymes is more believable.
Endowment Effect — NHS
If you feel you own something, you'll value it more.
Katy Milkman⁴ applied this to persuasive messaging in her fantastic 2021 study.
Stating "your vaccine is reserved for you" made readers 4.6% more likely to get vaccinated as the reservation language boosts feelings of ownership. The NHS applied this principle to boost uptake of the Covid-19 vaccination.
Don't say it's available, say it's reserved.
Specific Numbers — Forest
In a 2006 study⁵, consumers saw ads for a fictitious deodorant.
Some were told it lasts "exactly 47% longer than rivals"
Others were told it lasts "more than 50% longer than rivals"
Which message do you think worked? It's probably not what you'd expect.
The precise 47% claim was deemed 10% more accurate by 199 participants.
Why? Well, it's the specific number. Specificity enhances the perceived accuracy and trustworthiness of claims.
And Forest applies this brilliantly in their 2024 billboard.
"51,899,782 free minutes" is more persuasive than "lots of free minutes".
Please reply. I read (and respond) to every email you send—that's 192 emails in 2025 if you're counting.
And if you have any Valencia tips, let me know — Phill
¹Aronson, E., Willerman, B., & Floyd, J. (1966). The effect of a pratfall on increasing interpersonal attractiveness. Psychonomic Science, 4(6), 227–228. https://doi.org/10.3758/BF03342263
²Shotton, R. (2023). The illusion of choice: 16 ½ psychological biases that influence what we buy. Harriman House.
³McGlone, M. S., & Tofighbakhsh, J. (2000). Birds of a feather flock conjointly (?): Rhyme as reason in aphorisms. Psychological Science, 11(5), 424–428. https://doi.org/10.1111/1467-9280.00282 ⁴Milkman, K. L., Patel, M. S., Gandhi, L., Graci, H. N., Gromet, D. M., Ho, H., Kay, J. S., Lee, T. W., Rothschild, J., Bogard, J. E., Brody, I., Chabris, C. F., Chang, E., Chapman, G. B., Dannals, J. E., Goldstein, N. J., Goren, A., Hershfield, H. E., Hirschhorn, S. W., … Duckworth, A. L. (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. https://doi.org/10.1073/pnas.2101165118
⁵Schindler, R. M., & Yalch, R. F. (2006). It seems factual, but is it? Effects of using sharp versus round numbers in advertising claims. Advances in Consumer Research, 33, 586–586.
As a behavioural science practitioner, I believe in the peak-end rule*
The Anchoring Effect Read online "𝘚𝘰𝘶𝘵𝘩𝘦𝘯𝘥: 𝘕𝘰𝘵 𝘲𝘶𝘪𝘵𝘦 𝘵𝘩𝘦 𝘔𝘢𝘭𝘥𝘪𝘷𝘦𝘴 𝘣𝘶𝘵 𝘸𝘢𝘳𝘮𝘦𝘳 𝘵𝘩𝘢𝘯 𝘎𝘳𝘪𝘮𝘴𝘣𝘺." Why does this line work? Well, it's due to a great use of the 𝐚𝐧𝐜𝐡𝐨𝐫𝐢𝐧𝐠 𝐞𝐟𝐟𝐞𝐜𝐭. Anchoring = "𝘝𝘢𝘭𝘶𝘦 𝘱𝘦𝘳𝘤𝘦𝘱𝘵𝘪𝘰𝘯 𝘥𝘦𝘱𝘦𝘯𝘥𝘴 𝘰𝘯 𝘸𝘩𝘢𝘵 𝘺𝘰𝘶 𝘢𝘯𝘤𝘩𝘰𝘳 𝘪𝘵 𝘢𝘨𝘢𝘪𝘯𝘴𝘵." In a 2022 study¹, 404 shoppers tested how reference prices affect perceived value. When Ben & Jerry’s ($3.99 for 16oz) was shown next to Walmart’s cheaper $1.99 tub, only 27% rated Ben & Jerry's as great value. But when paired with a costlier $4.99 Halo...
Goal Dilution Effect Read online Keen listeners of Nudge will have heard Richard Shotton explain how Five Guys succeeded because they limited the number of items on their menu. Taken from Shotton's episode in late 2025. They focused on just burgers and chips. That helped them improve and benefit from economies of scale. But it also helped them psychologically, due to the goal dilution effect. Here's why: In a 2007 study by Zhang and Fishbach¹, participants were given information about how...
Pratfall Effect Read online A few months ago on Reddit, someone asked, "Is this the best Black Friday marketing campaign?" Personally, I think it's disingenuous garbage, but clearly, something about this type of ad resonates with some. And it might be because of the first two words. "We're sorry." In 2024¹ a number of researchers from Belgium ran four experiments. They tested what happened when a company apologised for a trivial mistake. In one study, participants were shown an email from a...