Chapter 3: From homo economicus to homo manipulable

To understand deceptive patterns, we need to understand some concepts from the field of economics. For a long time, economists believed humans were perfect information-processing machines – able to consume, understand and reason with all the information provided to them at all times. They called this idea ‘homo economicus’. If you think about the number of mistakes we all make in our daily lives, you’ll know this is a really daft idea. Still, it’s understandable. Economists needed to start somewhere, and they also needed to start with a relatively simple model of how humans behave, otherwise the maths gets really complicated.

It’s only relatively recently – in the late 20th century – that economists have updated their views. It was considered groundbreaking when Herbert Simon introduced the idea of ‘bounded rationality’.1 He posited that ‘both the knowledge and the computational power of the decision maker are severely limited’ and ‘we must distinguish between the real world and the actor’s perception of it and reasoning about it’. In other words, we can only remember a certain amount of stuff before we start forgetting; we can only do a certain level of mental arithmetic before we get it wrong; and we can only read so much complex text before we become fatigued and start to misunderstand things.

To be even more reductionist, bounded rationality means we muddle through life doing our best with limited faculties. As someone who once fell down the stairs at night because I had forgotten that I’d moved house, I can attest to that.

More recently, behavioural economics has greatly extended the idea of bounded rationality. Richard Thaler is considered one of the founders of behavioural economics, and he won the Nobel prize in 2017 for ‘incorporating psychologically realistic assumptions into analyses of economic decision-making’.2 It turns out that understanding the ways in which people can do dumb things is really useful for economic modelling. Particularly when it comes to understanding the causes of the common mistakes we all make.3

‘Real people have trouble with long division if they don’t have a calculator, sometimes forget their spouse’s birthday […]. They are not homo economicus; they are homo sapiens.’
—Thaler and Sunstein (2008)

Physically, our bodies have lots of common flaws. For example, the trachea and oesophagus are very close to each other. Most of us are familiar with the dangers of accidental choking. Knowing that flaw and sharing the knowledge has helped humanity a great deal. The same applies to human reasoning and...

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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.