The Persuasiveness of Uncertainty

Persuasion is a much-studied subject, but most work examines persuasion in settings that don�t resemble consumer settings. If you want to persuade voters or jurors, for example, there are proven persuasion tactics you can learn. But for retailers, the guidance is slim. Uma Karmarkar, from Stanford University recently made a contribution that will help correct this deficiency.

In three experiments involving hundreds of students, Karmarkar studied three elements of a typical consumer persuasive message. First, the strength of the arguments, second, the expertise of the speaker, and third, the certainty of the recommendation. Imagine, for example, that you�re selling lawn mowers. You�ve qualified the customer -- he needs a lawn mower and has the money to pay for it. Next, you present your best-selling model and introduce its features. You�re the expert on lawn mowers, and part of your pitch is to educate the customer. Finally, you give your strong recommendation that this lawn mower will meet his needs and he should buy it. You are certain this lawn mower is right for him. In this example, the three typical features of a persuasive consumer message are present: strong arguments, expert source, and certainty in the recommendation.

In her experiments, Karmarkar varied the strength of each of these three elements. For example, one combination included strong arguments, a non-expert source (a typical customer), and certainty. Another combination included weak arguments, an expert source, and uncertainty, and so on. Logic suggests that strength in each element would lead to the greatest persuasion: strong arguments + expert source + certain recommendation = most persuasion. Surprisingly, that�s not what Karmarkar found. But although she didn�t find what logic would have predicted, she did find two consistent patterns of enhanced persuasion in all three experiments. The two strongest persuasion tactics were 1) expert source, strong arguments, and uncertain recommendation; and 2) non-expert source, strong arguments, and certain recommendation. The strength of these two combinations far outstripped the others.

Karmarkar explains it this way. The most persuasive message is not the one that convinces another to take action. People make their own decisions. The most we can achieve in a consumer setting is to trigger thinking. That�s persuasive because most messages in consumer settings don�t do that. We see attractive models talking about a product or service, but we think about the model. We don�t imagine ourselves using the product. We don�t think about how our lives would be better with the service.

The two patterns Karmarkar discovered trigger thinking because they�re unexpected. Consumers experience surprise, and this causes them to think, and they think about the arguments that were presented. Both patterns include strong arguments, so it is triggering thinking about the strong arguments that leads to action.

Consider, for example, an unfamiliar restaurant where you stop and chat with a patron waiting outside. She doesn�t know anything about restaurants, but she just had a great experience at this one, and she�s sure you will, too. (Non-expert, strong arguments, certainty in recommendation.) Karmarkar�s findings suggest that this is a powerful combination, and you�ll probably go in and order a meal.

Next, let�s go back to the garden center. The expert salesman describes the superior features of his best-selling lawn mower but adds that there are many good mowers on the market and he�s not sure if this is the best one for this customer or not. (Expert source, strong arguments, uncertainty in recommendation.) Karmarkar�s findings suggest that this is also a powerful combination, and you might just buy this lawn mower.

Both patterns include strong arguments. The non-expert includes certainty in recommendation. The expert included uncertainty in recommendation. Both trigger surprise and further thinking, and the thinking is directed to the strong arguments. With this combination, persuasion is significantly greater. Karmarkar measured it.

For experts, there is only one choice. You must be gracious to competitors and respectful of the decisions your customers must make. You will never know all the factors that weigh on buying decisions, and the best recommendation you can make is an uncertain one. Karmarkar�s research suggests that this approach will cause surprise and trigger further thinking. If your arguments are strong, the customer will consider them. This is the most persuasive you can be.

But what if you�re not the expert? Many times, customers will not expect to encounter an expert, and when this is true, you have another choice. You can be the non-expert, present your strong arguments, and give a certain recommendation. You�re just another consumer like them. But your experience with the product leads you to your certain recommendation . . . an unexpected certain recommendation. Surprise will trigger further thinking which will lead to the strong arguments, and, hopefully, a purchase decision.

These are persuasion tactics that retailers should commit to memory and practice implementing.

Reference: Karmarkar, Uma, and Zakary Tormala (2010) Believe Me, I Have No Idea What I�m Talking About: The Effects of Source Certainty on Consumer Involvement and Persuasion. Journal of Consumer Research, 36, 1033-1049. www.businesspsych.org

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