Consistency; judging a book by its cover.
Consistency allows you to judge a book by its cover.
Predictability allows to make an informed choice based on its author.
While I was working at Apple, the Human Interface Group published an update to their Human Interface Guidelines. The Book as it was known came out in 1995. Nearly 400 pages covering everything from menus and windows to the standard order of actions and icons. It also covered the underlying principles of human interface design—like metaphors, feedback, and of course consistency.
A number of the designers—many of them contributing authors, who walked around campus with The Book tucked under their arms, ready to quote chapter and verse. It would land with a thud as they sat down to meet with product managers, engineers, and of course designers when they felt the users’ perceived sense of stability was being threatened with some heretical design.
The Book contained many dos and don’ts, chief among them don’t do anything that was not included in the book. According to the authors the introduction of these nonstandard designs would clutter the UI, confuse your users, and lead to systemic instability. Gasp!
If you have read any of other my posts it should not surprise you to learn I never followed these guidelines for any of the products I designed while I was at Apple. I was the Martin Luther to their Leo X threaten with heresy.
Even though I had research data showing how my nonstandard designs outperformed the guidelines from The Book, they still demanded I revert them to adhere to The Book. Even when I presented them with use cases that their book never covered—like wireless networks, internet search, and collaborative tools, etc., I was told to cobble together a UI from The Book.
For them it was better to be consistent than to actually solve the problem. And the reason is because consistency is easy.
It’s easy to explain, never any surprises
It’s easy to document, you can write style guides, checklists, design standards, etc.
It’s easy to test, you can look at the design to see if its consistent.
It’s easy to build, like an Ikea bookshelf—all the pieces snap together easy-peasy-lemon-squeezy.
It’s easy to manage, a limited few control the actions of many.
In short its easy because you don’t have to think.
You also don’t have to take responsibility. You are just following the guidelines.
The pinnacle of the The Book’s success was System 7, quickly followed by System 7.5—which sucked less. Don’t believe me? Here is a picture of the t-shirt the development team printed to celebrate its launch.
Consistency is formulaic and it has a shelf life. It is fabricated by a few people in a moment in time, with only a historical understanding to guide the policies and bounded understanding of what it is being designed. Its not sustainable. It can’t scale. And worse; it inhibits innovations.
Innovations that could be technological, social, cultural necessitate a reassessment of the underlying policies embedded in the consistent state. Consistency cannot address the future indeed too often the keepers of the consistency try to hold back the future. Everyday we are seeing the evolution of generative AI, the emergence of new practices around prompt design and prompt engineering that are not covered in the guidelines. The shift from creator to director changes the metaphors and user experience.
Which is why I champion the concept of Predictability. Predictability requires understanding of your users and the emerging technologies, it requires thinking and judgement, and it can only evaluated by those who experience it.
