Over the past two years, Which? research into fake reviews has discovered how unscrupulous sellers are able to 'game' online platforms to misrepresent products and services.
In a one of a kind behavioural experiment, the true impact of fake reviews has now been demonstrated.
Our research tested a range of scenarios involving fake review activity, and in every one it showed an adverse effect on consumer behaviour. In the worst instance, we found that people were more than twice as likely to buy a poor-quality product that had been boosted by fake reviews.
Watch our video to find out how fake reviews could be manipulating you.
We asked 10,000 people to complete a shopping task using images designed to look like the Amazon website - although pages and content that were shown to participants as part of the survey were not real Amazon pages or content. Amazon was chosen as it's likely to be familiar to the greatest number of customers, but Which? believes the findings of the experiment are equally applicable to other online platforms hosting user-generated reviews.
Participants were asked to choose one of three product types: headphones, dash cams or cordless vacuum cleaners - areas where Which? has previously found clear evidence of fake reviews.
In each category, participants were shown five identically priced products: a Which? Best Buy, three 'fillers' with mediocre reviews and a Don't Buy, which may or may not have been manipulated by fake reviews. They could read information about the five products, including seven reviews for each, before deciding which they would most like to buy in real life.
In each of six randomly allocated groups, varying degrees of fake review activity were shown, from inflated star ratings to the addition of a platform endorsement label, which can often be influenced by high review ratings.
We also added text that Which? investigations have previously found in suspicious or fake reviews, such as repetition in the subject titles and review text, overly positive language and grammatical errors.
We then looked at the impact this fake review activity had on product selection.
The graph above shows the percentage of people who chose the Don't Buy product. In a control group where no fake review activity was simulated, just over 10% of people selected it. In each of the other groups, which applied varying degrees of fake review activity, a significantly higher proportion of people chose this product.
Treatment group four, which involved an inflated star rating, fake review text and a platform endorsement to further indicate product approval, saw a 136% increase in demand for the Don't Buy product, meaning participants were more than twice as likely to buy it.
Even just increasing the average star rating and number of reviews on the Don't Buy product led to an increase of 55% when compared with no fake activity.
Which? has illustrated many of the pitfalls of fake review activity in a number of investigations. In February this year, we showed how platform endorsements such as can be flawed - sellers were able to artificially achieve endorsement status through the use of tactics such as incentivisation, which is against Amazon's policies. In September 2019, we reported how could help push hotels up the rankings.
Which? has received hundreds of emails from consumers reporting fake review activity online, along with examples of the real impact it has had.
Jeff, 72, wanted to buy a thermometer from an online marketplace in order to check himself for potential COVID-19 symptoms. He told us: 'Conventional thermometers were in very short supply, but there were posh-looking ones with rave customer reviews, so I selected the one with the most five-star reviews. It arrived promptly and an £8 voucher was included, valid if I too gave the thing a five-star review.
'When I tried it out it didn't work. At least, if I took my temperature five times, it decided I was five different people, with temperatures ranging all over the place. I decided to return the thermometer and the voucher. I'm furious that companies are allowed to tout for five-star reviews in this way. Reviews used to be so dependable and balanced: often you'd see only negative reviews. These days it all looks like marketing.'
Grant bought two retro games consoles for his children on an online marketplace, the item had received 1,700 ratings and an average of 4.5 stars, but he told us: 'On receiving the consoles I was very disappointed to receive in the packaging a solid plastic business card with the following text on it. “Dear Customer: If leave a positive review, you will receive a gift card of £15/15 euros/C$15/$15. Please send the review and Order ID to the email address on the back. Thanks for your attention”.
'How can we believe reviews and trust them if people are effectively being paid by the supplier to leave favourable reviews of their product?'
Which? has been supporting the work of the CMA, who estimates that £23bn a year of consumer transactions are influenced by online reviews, to try and fight this problem.
The evidence we've presented reinforces the need for the CMA's recently announced investigation into misleading online reviews and why the regulator must take the strongest possible action against sites that fail to tackle this problem.
Caroline Normand, Which? director of advocacy, said: 'Which? has found categorical evidence that people are at huge risk of being misled by fake reviews, which is particularly worrying given people are shopping online more than ever during the coronavirus pandemic.
'Online platforms must put more effective measures in place to stop unscrupulous sellers gaming the system with ease, otherwise the CMA needs to take strong action against these major sites.'
When we presented our evidence to Amazon, a spokesperson said:'We want Amazon customers to shop with confidence knowing that the reviews they read are authentic and relevant.
'We have clear policies for both reviewers and selling partners that prohibit abuse of our community features, and we suspend, ban and take legal action against those who violate these policies.'
Customers concerned about the authenticity of online reviews are encouraged to report this to the platform so that it can investigate. You can also email examples of fake reviews, incentivisation, or other suspicious review behaviour to .