Part 4: Harms caused by deceptive patterns

Deceptive patterns are very common. A 2022 research project by the European Council found that 97% of the websites and apps reviewed contained at least one deceptive pattern.1 In Chile, a 2021 research project by the National Consumer Service of Chile, SERNAC, found that 64% of the e-commerce websites reviewed had deceptive patterns.2 In the United States, a 2019 research project by Moser et al. found that 75% of the e-commerce websites reviewed had at least sixteen features that encourage impulse buying.3 In 2020, Soe et al. analysed the cookie consent notices of 300 news and magazine websites from Denmark, Norway, Sweden, UK and USA. They found that 99% of them used deceptive patterns.4 In 2023, the EC and CPC network published a report that documented a sweep of 399 online shops and 102 apps; they found that 148 of the online shops (37%) and 27 of the apps (26%) contained deceptive patterns.5 The evidence is overwhelming, but if you want more, you can view a comprehensive table of further evidence in Annex C of the OECD report ‘Dark Commercial Patterns’.6

So, it’s clear they are widespread, but what kinds of harm do they actually cause? When you think about deceptive patterns from your own personal perspective, the first thing you might think of is the emotional impact, feelings like annoyance and frustration. Although it’s normal to respond in this way, there are usually other, even bigger negative consequences to bear in mind. You can look at the harm from different perspectives: harm to individuals; harm to groups in society; and harm to the marketplace...7

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Since 2010, Harry Brignull has dedicated his career to understanding and exposing the techniques that are employed to exploit users online, known as “deceptive patterns” or “dark patterns”. He is credited with coining a number of the terms that are now popularly used in this research area, and is the founder of the website He has worked as an expert witness on a number of cases, including Nichols v. Noom Inc. ($56 million settlement), and FTC v. Publishers Clearing House LLC ($18.5 million settlement). Harry is also an accomplished user experience practitioner, having worked for organisations that include Smart Pension, Spotify, Pearson, HMRC, and the Telegraph newspaper.