Strategic Manipulation of Online Reviews: An Experimental Investigation

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This dissertation contains four experimental studies that deal with post-consumption effects of manipulated online reviews. Prior research shows that online consumer reviews are highly influential in forming buyers' pre-purchase opinions, substantially affecting their purchasing decisions. This creates incentives for firms to manipulate reviews in their favor. While manipulation of reviews impacts product sales, at least in the short run, the long run effects of review manipulation are complicated and have not received any attention. In principle, once the product is consumed, buyers should be able to form their own unbiased opinion about the product quality. Such post-consumption opinion, in turn, should determine their re-purchase decision and the contents of their consequent genuine reviews. This dynamic, if existent, can potentially offset the effect of manipulated reviews and can also help expose dishonest firms and so deterring them from engaging in this type of fraudulent activity. By conducting a series of experiments, involving an experience good as well as a professional service, I investigate how consumers respond to manipulated reviews. Specifically, I examine the post-consumption effects of positively and negatively manipulated reviews on consumers’ rating behavior and on their intention to repurchase. In my first study, “The Effects of Manipulated Reviews on Post-Consumption Evaluation of Products,” by conducting a lab experiment, I examine participants’ reaction to manipulated reviews after eating a food item. The result of this study shows that the effect of manipulated reviews is not corrected by consequent genuine reviews. Rather, both positively and negatively manipulated reviews create a substantial bias in the ratings of consumers in the direction of manipulations. In the second study, “How much is a star worth,” by reducing the magnitude of manipulation from what was used in Study 1, I examine the nature of the relationship between the degree of manipulations and the resulting effects on consumers. The results suggest that there exists a linear relationship between the degree of manipulation and its effect on the consequent rating behavior of consumers. In the third essay, “Manipulated Reviews and the Credibility of Online Platforms,” I examine the moderating role of source credibility on the effect of manipulated reviews on consumers’ rating behavior. Source credibility has been demonstrated to play an important role in the context of both online and offline persuasion. Comparing the result of this study with that of the first experiment reveals that consumers discount the information on online platforms to some degree, but not enough to cancel the social influence bias created by manipulated reviews. Finally, in the fourth study, “Manipulated Reviews in the Professional Service Domain,” I investigate the post-consumption effect of manipulated reviews in the domain of professional services, particularly, education. Online reviews are increasingly expanding to include professional services. To date, however, reviews on services have received very limited attention. Professional services are distinct, as a typical consumer usually lacks the needed knowledge to judge the quality of the offering. Our results show that manipulated reviews are influential in this domain, too, though with some differences in terms of the relative effect of positive and negative reviews. Taking the role of gender of consumers into account provides some interesting insights about the differences. At the end, using the results from all the four studies, I focus my attention on the role of consumer gender on influenceability. I also investigate whether positive and negative reviews have symmetric effects on consumers. The results suggest that whereas males are influenced more by negative reviews, females are influenced more by positive reviews.

Embargo status: Restricted until 01/2023. To request the author grant access, click on the PDF link to the left.

Online Consumer Reviews, Social Influence bias, Strategic Manipulation