Word of mouth is rightly held in very high esteem by marketers the world over.  Consumers have much more credibility than you as a company so when they recommend you to their friends then it carries an awful lot of weight.  Logic would suggest that when they talk to their friends that what they say is far and away the most important thing.  Research however suggests otherwise.

The paper, titled "How Interest Shapes Word-of-Mouth over Different Channels", was produced by Wharton marketing professors Jonah Berger and Raghuram Ivengar, and it suggests that the medium used to communicate with friends is as important as the message itself.

The pair analysed two data sets containing thousands of discussions between people.  They then conducted an experiment in the lab whereby they manipulated these conversations to examine the effect.  The results are fascinating and crucial for anyone looking to generate word of mouth.

They found that the level of interest in a product matters much more when people communicate through asynchronous means, ie through blog posts or via emails.

When you talk face to face however, or on the telephone, social conventions dictate that you respond instantly, therefore the attractiveness of the product isn't as important as it's harder to ignore what the other is saying.

"It's awkward to have dinner with a friend in silence, or ride in a cab with a colleague without conversing, so rather than waiting to think of the most interesting thing to say, people will talk about whatever is top-of-mind to keep the conversation flowing," they write. "It's not that people do not have enough interesting things to talk about; rather, they do not have the time to select the most interesting thing."

If you're reading an email or a blog however you can choose to ignore it if you want, or take your time in crafting a response.  It's ok to share something you like on Facebook and have no one like it, but if you did the same face to face you would feel very socially awkward.

"A really simple way to think about it is the following," Berger notes. "Imagine if you're online and someone sends you something. You don't have to reply. You're only going to share things when they cross a certain threshold of interesting. The option of not saying anything is fine in a discontinuous conversation."

So you need to not only pick the right message but also the right medium if you want your product to go viral.

"Practitioners often believe that products need to be interesting to be talked about, but our results suggest they are only right for certain word-of-mouth channels," the authors note in their paper. "If the goal is to get more discussion online … framing the product in an interesting or surprising way should help. Ads or online content that surprises people, violates expectations or evokes interest in some other manner should be more likely to be shared."

If you want offline word of mouth for instance then it isn't as important for your product to be exciting, but of course it does still need to be a good product.  Food for instance is one of the product categories most discussed in conversation, so thinking how to trigger people to include you in covnersation is likely to generate best results for you.