When more is less and why three really is a magic number

How many benefits should we list about ourselves when we are trying to convince a customer to do business with us? More must surely be better, right? It’s one of the most common questions I get when helping clients design websites and collateral and now there’s an answer – three.

Researchers hypothesised that including more than three points affirming your greatness would end up undermining the effectiveness of your proposition.

Why? You doth protest too much.

It seems the more we preach about ourselves, the more likely we are to trigger scepticism in customers wary of persuasive tactics.

In a series of experiments, participants were asked to rate their reaction to statements about products, potential romantic partners, in-store advertising and even politicians.

This is how one of the statements asked about shampoo, for instance.

“Imagine you are reading one of your favourite magazines and an ad for a new brand of shampoo catches your attention. You decide to read the ad carefully to see if it is worth switching to this new product. The ad says this new shampoo does the following…”

One, two, three, four, five or six substantiation points then followed the statement.

The sweet spot is three

Results showed that consumers perceived four or more positive claims as less positive than three positive claims, and that three was better than one or two. Think of it as an inverted U where performance improves as you increase to three, but falls once you’ve passed this magical tipping point.

The results also indicated that the negative effect of too many claims is related to how ‘on guard’ people are about being persuaded. If they are pre-occupied by something else (in research they were asked to memorise a seven digit number) they forgot to be sceptical and the number of claims didn’t have the same significance. 

Before you race off to apply these findings…

A caveat about this research – it was based on self-reports, so participants gave a rating of their reaction. Giving an indication of their intended rather than real behaviour might well have been their honest answer, but as I’ve noted previously (here and here) there is often a gap between what people say and what they do.

Therefore if you are thinking of applying this research to your collateral or website, I would recommend setting up an A/B test where everything but the number of claims stays the same and you record the observed, actual behavioural response.

So, the lessons are;

• Three is best
• May depend on how pre-occupied people are
• Test real behaviour

 Bri Williams runs People Patterns, a consultancy specialising in the application of behavioural economics to everyday business issues.