Keller Center for Research

How Language Shapes Word of Mouth's Impact

March 1, 2018

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Grant Packard, PhD and Jonah Berger, PhD

One way the internet is shaping consumer purchase decisions is by introducing transparency. Today, consumers can express their opinions about a product, a property, or almost anything. A few lines written by an anonymous user in a completely different geographic location and time zone can impact success or failure in the marketplace.

We examined how variations in the language reviewers use to endorse products impacts persuasion.

Word-of-Mouth Endorsements

We observed two general ways people endorsed products linguistically: (1) implicit endorsements and (2) explicit endorsements. Implicit endorsements entail the sharing of one’s own personal positive opinion, while explicit endorsements declare that the product is appropriate for other potential customers. For example, an implicit endorsement might say, “I like this house,” while an explicit endorsement could say, “I recommend this house.” While both of the statements are positive, the first shows the speaker’s declaration of his/her own tastes while the second shows the speaker’s declaration that something is appropriate for an audience.

In our research, we set out to determine whether—

1) there are meaningful linguistic variations in how consumers endorse products to one another;

2) a person’s knowledge about the product category they are talking about (e.g., books, real estate, wine) moderates the endorsement language that an individual uses, and;

3) these language variations affect the persuasive impact of word of mouth.

We report the results of a field data analysis of over 1,000 online reviews and four experiments to answer these questions.

Research Observations

First, the authors analyzed over 1,000 real consumer reviews and the review writers’ purchase histories to identify common endorsement styles, and to test whether the extent of a person’s experience with a product category (e.g. purchase volume or frequency) impacted style preferences. Results reveal explicit endorsements (e.g., “I recommend…”, “I suggest…”) and implicit endorsements (e.g., “I like…”, “I enjoyed…”) as the two dominant styles. Consumers who had bought fewer products through the website were almost four times more likely to explicitly endorse products than those who had a greater purchase history with the firm. This suggests that product category experience may be linked to endorsement style.

Next, two experiments formally tested the relationship between product category knowledge and explicit endorsement and examined the mechanism behind this effect. Results confirmed that category novices are significantly more likely to “recommend” products than experts and that lower awareness of variation in others’ tastes (preference heterogeneity) for category novices drives this result. In short, less knowledgeable consumers tend to imagine that if they like something, say a particular property, everyone else will too. They therefore “recommend” it to others more frequently. In contrast, consumers who are more knowledgeable about real estate might appreciate that some people may like large backyards, while others may prefer a small patio. As a result, rather than recommend things to others, knowledgeable consumers tend to just describe their own preferences when endorsing something (e.g., “I enjoyed…”).

A set of additional experiments studied endorsement style’s impact, testing how explicit endorsements affect persuasion, and the mechanisms underlying this effect. Explicit recommendations (e.g., “I suggest…”) generated perceptions that the information source was more expert, and further, that they liked the product more than the implicit style (e.g., “I liked…”). These perceptions then led to increased purchase intentions for the reader.

Finally, a unique “yoked” study design demonstrated that, overall, the relationship between consumer knowledge and endorsement styles can lead users of online product information to make worse decisions. Specifically, more novices chose an objectively inferior (vs. superior) product and then chose to explicitly recommend it in an online review. Participants in another study “yoked” to this one saw the actual distribution of “recommends” and “likes” for the products in the word-of-mouth condition. This led them to be even more likely to choose the worse product versus those asked to make the same decision without word-of-mouth information. 

Summary of the Results

With increasing word-of-mouth information available online, the influence cast by this mode of communication has also increased. Our research shows that the language used by people to endorse a product or a service has an important influence on how other consumers react to that endorsement.

Compared to more implicit endorsements (e.g., “I liked it” or “I enjoyed it”), explicit endorsements (e.g., “I recommend it”) are more persuasive and increase purchase intent. This occurs because explicit endorsers are perceived to like the product more and have more expertise.  Looking at the endorsement language consumers actually use, however, shows that while consumer knowledge does affect endorsement style, its effect actually works in the opposite direction.  Because novices are less aware that others have heterogeneous product preferences, they are more likely to use explicit endorsements. Consequently, the endorsement styles novices and experts tend to use may lead to greater persuasion by novices. These findings highlight the important role that language, and endorsement styles in particular, play in shaping the effects of word of mouth. This relationship was observed in both product and service contexts.

Implications for the Real Estate Industry

Like many other industries, the real estate industry is impacted by reviews written on digital platforms. A client can easily write a review about a property and/or a real estate agent and create very powerful connectivity. Some direct implications of our research for the real estate industry are:

  1. The language used by a customer about a property will influence other potential home buyers. For example, a potential customer is more likely to be influenced by a customer who writes “I recommend this property” or “I recommend this agent” than someone who writes “I like this property.” Hence, explicit endorsements will appeal more than implicit endorsements, especially when it comes to important investments such as a home.
  2. A more knowledgeable consumer, who does thorough research before purchasing a property, is more likely to write an implicit endorsement. While such reviews might not be perceived to be as helpful for the agent and the company, they give an indication that the consumer has knowledge and expertise in the home-buying process. When speaking with such consumers, a real estate agent should mention the advantages of the property which will help the property stand out in the crowd. For example, when dealing with more knowledgeable consumers, the agent should not just speak about the advantages of a property but also give a comparative study of this property and other properties in other communities.
  3. Implicit endorsements are very common, but they are less compelling to other potential home buyers. Hence, it is in the best interest of the agent/real estate company to focus on obtaining explicit endorsements. One way to gain explicit endorsements is by giving a better client experience based on the buyer’s background and lifestyle. With a lot of data freely available on the web and social media, understanding the end customer is less of a challenge than it used to be.

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Recommended Reading

Packard, Grant and Jonah Berger (2017), “How Language Shapes Word of Mouth’s Impact,” Journal of Marketing Research, 54(4), 572-88.

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About the Authors

Grant Packard, PhD
Assistant Professor of Marketing, Wilfrid Laurier University
Grant Packard’s (PhD – University of Michigan) research explores self-concepts, motivation, language, perception, and interpersonal influence in interactions among consumers and with firm agents. His research has been published in top-tier journals and presented at leading conferences. Before entering academia, Grant was a marketing executive for Chapters/Indigo and Excite Canada and worked with advertising agencies DMB&B New York and BBDO Toronto. In 2002, Grant was profiled as one of Canada’s top 30 marketers under the age of 30 by Marketing Magazine.

Jonah Berger, PhD
Associate Professor of Marketing, University of Pennsylvania
Jonah Berger (PhD – Stanford University) has spent over 15 years studying how social influence works and how it drives products and ideas to catch on.  He’s published dozens of articles in top-tier academic journals, consulted for a variety of Fortune 500 companies, and popular outlets like the New York Times and Harvard Business Review often cover his work. Professor Berger is the author of the New York Times and Wall Street Journal bestseller Contagious: Why Things Catch On and a new book on the hidden forces that shape behaviour, Invisible Influence.

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