Article: Monday, 16 April 2018

Consumers increasingly use online product reviews to make purchasing decisions – so businesses are increasingly offering money to people who write online product reviews. Usually, those payments are very small amounts – but that might do more harm than good, according to research by Dr Christilene du Plessis of Rotterdam School of Management, Erasmus University (RSM). She discovered that consumers put greater trust in reviews when the reviewer is paid more.

Existing research shows that 92 per cent of consumers do trust product reviews, and good reviews are an important predictor of sales, says Du Plessis. And now, an increasing number of companies will pay reviewers to write them. Five years ago, just two per cent of reviewers on were paid, but in 2018, more than half of reviews come from paid reviewers.

This leads many businesses to assume that they must pay their consumers to review their products if they want to sell to new potential customers. But are paid-for reviews really effective?

Participants who were paid either a large incentive of € 10.00 or no incentive at all felt more legitimate as reviewers, and were more certain about the review of the product that they wrote.


In a recent study, Du Plessis investigated how monetary incentives affect how reviews are written, and how readers perceive them. In the study’s first experiment, 237 participants tried out a pair of headphones and wrote a review about them. They also indicated how legitimate they felt in their role as reviewer. Results showed that reviewers who were paid a small incentive of € 0.10 felt less legitimate in the reviewing process, and as a result, more uncertain about the review they wrote.

Participants who were paid either a large incentive of € 10.00 or no incentive at all felt more legitimate as reviewers, and were more certain about the review of the product that they wrote.

Sensing uncertainty

Du Plessis then conducted a similar experiment on Amazon’s MTurk, one of the main platforms through which companies pay for reviews. In this study, 335 participants tested an online game and wrote a review about it. Some were paid US$ 0.10 and others US$ 10.00. Again, the results showed that participants who were paid a small amount were more uncertain of their attitude towards the product than those who were paid more.

The researcher then wanted to find out how the writers’ uncertainty affected how their readers evaluated the products. In the subsequent experiment, 267 participants wrote a review of yogurt and rated how uncertain they were of their attitude towards the product. Next, 268 other participants read the reviews and then evaluated the quality of the yoghurt based on those reviews.

Readers who had read reviews for which a small incentive had been paid gave lower evaluations than readers who had read reviews whose writers had been paid more or who had not been paid at all. Apparently, readers can sense the reviewer’s uncertainty and start to doubt the quality of the product, Du Plessis says.

When online reviews are increasingly important for predicting consumer behaviour, the practice of paying consumers small amounts to write those reviews may do more harm than good, says Du Plessis. It might be more effective to either pay substantially more, or to pay nothing, she concludes.

Christilene du Plessis

PhD Candidate

Rotterdam School of Management (RSM)

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