A dark pattern is a user interface carefully crafted to trick users into doing things they might not otherwise do, such as buying insurance with their purchase or signing up for recurring bills. Normally when you think of “bad design,” you think of the creator as being sloppy or lazy — but without ill intent. Dark patterns, on the other hand, are not mistakes. They're carefully crafted with a solid understanding of human psychology, and they do not have the user’s interests in mind.

The thing about dark patterns is that you design them from the exact same rulebooks that we use to enhance usability.

Nielsen’s 10 heuristics, probably one of the most well-known set of usability guidelines, date back to the early 1990s. If we take three of them and invert them, we can describe Apple's UI strategy in the above example.

Visibility of system status. Instead of showing key status information, hide it. Do this with unclear labels, obtuse navigation, and untimely messages.

Match between system and real world. Instead of "speaking the user's language," the system should use "weasel wording" so that it appears to say one thing while it really says another.

User control and freedom. Take advantage of your users' natural capacity to make mistakes to have them accidentally complete actions that are beneficial to your objective.

Trick questions

Marketing emails use this tactic all the time. You've probably seen this before. After you register to access something on the web, you're asked if you want to be placed on a mailing list. This particular approach is fairly standard but isn’t hugely effective because users have to take an explicit action to opt in. Chances are they’ll be in a hurry and a proportion of users won't even notice this text. Some websites use mandatory radio buttons with neither option (yes or no) preselected. This way the user can't get on to the next page without making an explicit choice. This in itself is still above-board. But if we think back to our anti-usability principles, we can see how not calling attention to this choice can be used to trick us into choosing something we don't actually want.

For instance, post-office.co.uk is designed to not draw any attention to the option, hoping that that you opt in by mistake. Here, a tick means no. It’s kind of clever because culturally, a tick is an affirmative action.

And they’ll definitely get opt-ins from those people who don’t pause to read this stuff. On the one hand this works — they will boost the mailing list opt-in rate — but a certain number of people will realize that the website is pulling a trick and they will swear angrily under their breaths. It’s probably not going to make them drop out just yet, but it is going to tarnish the brand's reputation, at least a little bit.