If someone throws 10 tennis balls at you, how many are you going to catch? You might just grab one before ducking to avoid the rest. But if they throw one ball, then another, and then another - chances are, you’ll catch them all.

This tennis ball scenario was an analogy used by John Pearce, one of the founders of the legendary ad agency CDP, to encourage brands to focus on one point at a time in their messaging.

But is this just a neat story or is there some truth in it?

The power of one

A psychological phenomenon called goal dilution suggests that Pearce was onto something. When we are told that an action can help us achieve multiple goals, rather than building trust in the effectiveness of the action, it has the opposite effect. The more goals it claims to meet, the less we believe that any goal will be successfully achieved.

Evidence for this comes from a 2007 study by psychologists Ying Zhang and Ayelet Fishbach at the University of Chicago and Arie Kruglanski at the University of Maryland. They devised an experiment to explore how people believe health goals (e.g. avoiding heart disease, maintaining strong bones) are met by means of lifestyle changes (e.g. exercise), when the number of goals was varied.

97 participants were asked to read three extracts from scientific articles on aerobic exercise, eating tomatoes and giving up caffeine. In each extract, there was one sentence that described how each of those lifestyle choices may satisfy one (heart health) or two (both heart health and strong bones) health-related goals. They were then asked to rate the extent to which each healthy lifestyle choice would be effective in pursuing the first goal listed.

Researchers found that an increase in the number of goals connected to a given action decreased the perceived effectiveness at meeting the focal goal by 5 to 10%.

In other words, if you’re told that a particular activity, such as jogging, is associated with multiple outcomes such as heart health and strong bones, you’re less likely to believe that jogging will help you achieve a healthy heart. But if you’re simply told that jogging improves heart health, that rings true.

What does this mean for you?

The goal dilution effect is important for brands deciding what to include in messaging. Let’s say a customer is looking for trainers to fulfil their need for lightweight running shoes. They’ll believe that a product focussing only on this feature will be more effective at achieving it. If the message is diluted with other goals – say, cheap price and pink laces – they’re less likely to believe the lightweight goal will be properly met. This is true even if the other features are relevant.

But don’t many people know this already? Well, yes, maybe some do. But it’s surprising how many ads fail on this front. So, understanding why single-mindedness is so important might will help you to talk round a client or colleague who is falling victim to message-stuffing in their communications. Far easier to persuade them by referring to a peer reviewed study than relying on your own opinion.

Perhaps ironically, considering the topic of this blog, behavioural science has many roles.

Sometimes it inspires counter-intuitive ideas that we might never consider otherwise (just think of the pratfall effect), sometimes it helps us sift the genuinely insightful ad land anecdotes from the misleading ones and sometimes it helps us persuade our colleagues or clients to make the right decision.

Each of these roles has a value, but the last is perhaps the one that is most underestimated.

The Behaviours Agency, are combining their strong creative thinking with insights from behavioural science to develop more impactful and effective ideas for clients in the B2B and B2C worlds and I’m pleased to be working with them as well.

By Richard Shotton

Behavioural Scientist