The rule of three in persuasion
To be most persuasive, use 3 positive claims at once in your message (e.g. ad, presentation). They are sufficient to show a pattern, but not enough to make people skeptical.
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How many positive claims should you make at once about your product?
After how many do people start to get skeptical?
As we’ve seen before, it’s better to talk about fewer excellent features than many good ones.
But recent research confirms the age-old rule (when you’re trying to persuade someone). Three is the perfect number.
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Use three claims, not more, to maximize how persuasive your message is
Impacted metrics: Customer acquisition
Channels: Marketing communications | Ads | Website | Packaging | Brand positioning
For: Both B2C and B2B
Tip type: Existing research (January 2014)
Use three positive claims about your product in your messages (e.g. ads, website, packaging) to maximize how persuasive you are.
If you use less than three, you miss out on being more persuasive.
If you use more than three, people become skeptical and you undermine the whole message.
Previous research has repeatedly established the “power of three” in several contexts. People like the number 3. For example, a 1979 study found that a message is most persuasive when repeated 3 times, rather than 1 or 5 times.
This study finds that 3 is the ideal number of positive claims to include in a message to maximize how persuasive it is (e.g. the phone has an amazing camera, is waterproof, and has a long-lasting battery).
The effect follows a ∩ pattern, with 1 or 2, as well as 4 or 5 (and beyond), being less persuasive than 3.
When 4 or more positive claims are used to persuade, people become skeptical and like the product less.
The effect disappears:
If the source of a message is neutral (e.g. not a marketer trying to promote their product). In this case, more positive claims beyond 3 continue to increase how positive the message is
If the recipient is mentally busy because they don’t have the mental capacity to become skeptical
For example, in experiments:
When people read claims about an improved cereal on the product’s packaging, 3 claims were 10.4% more persuasive than 4 (and the most persuasive). (see image below)
However, if they read the claims of the cereal on a neutral consumer report, 4 claims were more effective than 3.
(The effect applies when people feel they are being persuaded, but not when they aren’t - Click to zoom in)
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🧠 Why it works
When given up to three positive claims about a product, even by marketers trying to persuade us, we still perceive them as informative.
But once they become four or more, we become skeptical that someone is trying too hard to persuade us and we ‘switch off’.
Why three? Three is the smallest number at which we start to identify patterns. Once we feel we’ve identified a pattern, we think we’re ready to make a decision, for example:
When buying something we consider having three options to choose from as the right time to choose from one
In several U.S. states, three criminal convictions are used as an indicator that a person is a “career criminal” and should face life in prison (three-strikes laws)
The concept was already captured in a Latin proverb used in Medieval times: omne trinum est perfectum (“every set of three is complete”)
The study tested a broad set of objects (e.g. shampoo, a politician, restaurants, cereal, convincing a friend to date someone) so the principle should be widely applicable.
The study was performed on college students. Given that the effect seems to be stronger the more someone is aware of persuasion tactics, the jump in skepticism starting from the fourth claim could be even stronger for older adults (and marketers).
🏢 Companies using this
The power of three is quite well known and usually used by most experienced marketers - whether consciously or unconsciously.
For example, counterfeiting monitoring company Red Points explains ‘Why Red Points’ in three claims (Always-on, Industry expertise, Limitless takedowns).
Still, the temptation to talk about more is always very strong, and marketers often forget or can’t resist. Don’t fall into that trap, stay focused.
⚡ Steps to implement
Stick to three main claims for your product (e.g. Healthy, Crunchy, Tasty) and brand positioning (e.g. Gucci is “Seduction, Powerful, Accomplished”) to maximize how clear and persuasive your message is.
If people won’t have much time to read your message (e.g. a roadside billboard) it may still be better to stick to a single claim so people can read and process it with the little time they have.
If you really need to use more than three claims in your message, communicate them as secondary ‘additional information’ (e.g. on the back of the packaging) or use ways to reduce skepticism (e.g. admit a weakness).
🔍 Study type
Lab experiments. United States
Shu, S. B., & Carlson, K. A. (January 2014). When three charms but four alarms: Identifying the optimal number of claims in persuasion settings. Journal of Marketing.
UCLA Anderson School of Management, University of California and McDonough School of Business, Georgetown University. United States
Remember: This research could be disproven in the future (although this is rare). It also may not be generalizable to your situation. If it’s a risky change, always test it on a small scale before rolling it out widely.
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