The Blemish Effect and Why Bad Reviews Are Good

Let’s imagine you are looking to buy a book online. You are trying to choose between two books, neither of which you know much about, other than the information provided on the Amazon site where you are browsing. To help decide which book is best you scroll down to the review section. Based on these graphs, which book would you buy?


Book A has ten reviews, all of which rated the book 5 stars out of 5, perfect scores. Book B has slightly more reviews, 12 in total, of which 10 rate the book 5 out of 5 and a couple of others score the book 3 or 2 star.

Faced with this information, most people would want to delve deeper into those 2 and 3 star reviews. Let’s imagine that the details you find there relate to relatively unimportant facts for you like slow delivery time or the fact that the book cover was scuffed.

In this situation, many people will opt for Book B with its 4.6 star rating, rather than Book A with its perfect 5 star score. Under logical scrutiny this may seem counterintuitive, but researchers refer to this phenomenon as the blemish effect, a nature human bias towards the most credible, authentic information sources.

Book A loses out because its reviews are marginally less plausible than those given to Book B. We all know that nothing is perfect in this world, so the reviews for Book A may unwittingly raise alarm bells in our heads. “Surely not everyone can think that book is perfect,” we ask ourselves. Our thoughts may even turn to wondering whether the reviews have been placed there by friends of the author, or indeed by the author themselves.

And so it is that Book B wins. The majority of its reviews are very positive, while those that are slightly less glowing and, therefore, more credible, refer to aspects that are of low relevance to us. Of course, if the 2 and 3 star reviews had highlighted major issues with the writing, characters or story narrative we may well be put off buying Book B. But the fact that the bad reviews point to unrelated, peripheral attributes like delivery and cover scuffs allows us to demote them in our minds and put them down to bad luck or a one-off anomaly.

Researchers Shiv and Tormala at the Stanford Graduate School of Business studied this effect through a series of experiments in 2011 and showed that under specific conditions people can be more favourably disposed to a product when a small dose of negative information is added to an otherwise positive description. The way the information is presented and the amount of processing needed to digest it were also shown to have an impact on the beneficial extent of the blemish effect.

This is why marketers should embrace and welcome the occasional negative review. The obvious skill needed is to take immediate steps to remedy the issue, especially if it lies at the core of a highly valued aspect of the product or service delivery.

When presenting review information, it may also be helpful to present the positives first, followed by the (minor) negatives, along with response that show you have taken steps to remedy all previous customer dissatisfaction.

In a nutshell, accentuate the positives, and remedy the negatives. That’s the simplest way to make the occasional blemish work in your favour.

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