Persuasive Web: Where Psychology Meets Conversion

DAY 2: Tricks Online Book-Sellers and Vacation Sites Use to Persuade You

Posted in 30 Days of Persuasion, Social Proof by persuasiveweb on June 2, 2009

herd mentality

Read any good books lately?

When was the last time you came across a new or used book Web site or hotel aggregator site that didn’t offer consumer reviews? Would you go back if that was the case? Probably not, since user reviews are now the price of entry for any Web site that sells a large number of similar products or services.

It used to be that sites like and TripAdvisor were lauded for their user review systems. Epinions built an entire business around consumer-driven product reviews. Although the initial buzz has turned to quiet praise, why have so many sites continued to adopt user reviews? Likely because users began to expect – and then demand – user reviews.

But did you ever stop to think about what drove this expectation and why user reviews are so powerful?

User reviews are a form of social proof — a well understood persuasion principle — that is defined by Wikipedia as “a psychological phenomenon that occurs in ambiguous social situations when people are unable to determine the appropriate mode of behavior. Making the assumption that surrounding people possess more knowledge about the situation, they will deem the behavior of others as appropriate or better informed.

And further, “Social influence in general can lead to conformity of large groups of individuals in either correct or mistaken choices, a phenomenon sometimes referred to as herd behavior.

Do we really follow the crowd (sometimes to our own detriment) when making important decisions about where to spend our money?

It would seem so.

Yi-Fen Chen conducted a study in 2007 titled, “Herd behavior in purchasing books online” that examined recommendation systems and their impact on consumer behavior.

Here are some of her findings:

“The rapid growth of e-commerce has created product overload in situations where consumers have become unable to effectively choose products they are exposed to”

“The opportunity for consumers to choose among growing numbers of products has increased the burden of information processing before product selection”

So the Web has created too many choices for us (no revelation) – choices that may have always existed but never been fully exposed. Students of persuasion know that with an increasing number of choices, decisions become more difficult to make. And that’s a core benefit of user reviews: they are intended to make decisions easier for consumers, and the prevalence and popularity of reviews would appear to indicate that this is a real outcome.

But why do reviews make our decisions easier? Chen explains:

“’When people are free to do as they please, they usually imitate each other (Hoffer, 1955)”

“Informational cascades occur when individuals follow the previous behavior of others and disregard their own information”

I interpret this to mean that we (i.e., humans) don’t like to expend too much energy on making decisions. And when you consider just how many decisions we are forced to make in a single day(!), it’s no wonder, really. In fact, it’s this desire to make it through the hundreds of daily decisions and still have the energy to eat, talk, laugh, exercise, and play with our kids that is largely responsible for the study of persuasion – as so many of the persuasive principles we’ll discuss on this blog relate to our moving through life on ‘auto pilot’ – and how understanding this behavior can work for you and your Web business… to compel people to reach for their mouse and make the next click.

Chen also provides insight into specific elements of user reviews that can influence people’s behavior:

“Star ratings of books can influence consumer buying behavior and cause an informational cascade”

“Providing cues for eliciting herd behavior will influence consumers and lead to online herd behavior”

She references the following cues:

  • Star ratings
  • Sales volumes
  • Recommender system recommendations

As consumers come to rely even more on reviews in their complicated purchase decisions, cues such as these are quickly becoming part of what users expect to find on all Web sites. It’s no longer enough to provide a simple star rating. Users want more.

And finally, Chen makes a point of examining the influence that the source of reviews has on our behavior:

“Previous studies have demonstrated that source – expertise, trustworthiness, and attractiveness – positively influence consumer attitudes towards a brand and purchase behavior”

“Consumers are influenced more by ‘collective intelligence’ than by a small group of experts”

“Consumers clearly prefer to receive guidance from those perceived to be similar to themselves”

Her first point about expert reviews being potentially more influential is countered by the other two excerpts. I interpret them to mean that if a book has 5 expert reviews and 5 consumer reviews, people will lend more weight to the expert source. However, when the number of reviews by end users exceeds the volume of professional write-ups by a reasonable margin, there is power in numbers – and the numbers tip the influence in favor of the laypeople.

Chen’s final point about similarity is also insightful (and relates to another persuasion principle known as likeness), but I don’t see it being put into widespread practice by e-commerce sites. However, ratings and reviews vendor Bazaarvoice does offer the option to profile reviewers to its customer base, probably knowing full well that review readers will assign more credibility to people that appear to be just like them.

So, given Chen’s findings, how are popular book-selling Web sites doing in terms of their use of consumer reviews? Let’s take a peek at the powerhouse of the used book market, Victoria BC-based, and the leader in new book (and everything else) sales, (For anyone who hasn’t read the press release, Amazon acquired in August 2008.) does indeed provide book reviews (in this case for Cormac McCarthy’s “The Crossing”), but only in their most basic form. A review date and ‘smiley rating’ are the only two attributes of each review:

abebooks reviews, parent company of AbeBooks, does things a little differently and offers much more depth in their implementation of reviews. The book-selling behemoth incorporates a number of social proof elements into each set of recommendations in order to compel people to engage [and hopefully purchase]:

amazon reviews

With only a brief scan of its product pages, it’s pretty clear that Amazon understands consumers and what they have come to expect from an e-commerce site. And with an average annual conversion rate north of 15%, the company also has a firm grasp on the principles of persuasion and specifically the power of social proof.

[This post is getting a little long, so in part 2 – coming tomorrow — I’ll examine the implementation and effectiveness of consumer reviews on several hotel aggregator sites.]

And in the sprit of Amazon’s product reviews… was this blog post helpful? 🙂



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  1. […] wrote about social proof here and here, on days 2 and 3 of the 30 Days of Persuasion. The focus of those two posts was one […]

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