The question “How do we design things that humans can use?” is answered by first answering the much more psychological question: “Why do humans do things the way they do?” In The Design of Everyday Things, Norman answers both questions by first breaking down the actions a user takes into an execution phase and an evaluation phase, and the brain’s processing into the visceral, behavioural, and reflexive levels. The visceral level is the primal part of you that regulates hunger, lust, and fight or flight decisions. The behavioural level is still subconscious, but takes commands from the reflexive brain. If you place your hand flat down on a table and lift one finger at a time, it is your behavioural brain that sends electrical impulses through your body. It has expectations and receives feedback, making it the source of more complex emotions like frustration. Finally, the reflexive brain is responsible for conscious cognition. It learns by assigning blame and responsibility, which is why high-level emotions like guilt and pride come from this level.
Norman uses these concepts to clearly articulate the thought process that a human goes through when learning how to use something. First, the user discovers what actions are possible and how to perform them. The problem is, a lot can be done, but very few things should be done. The onus is on designers to provide appropriate signifiers to users so that they don’t choose to execute an unintended action. A product is intuitive if it is clear how to execute an action. Designers of shitty products blame their failures on the stupidity of users—“if only they read the instruction manual!” But unintuitive designs are fallible to human error even from the most meticulous users.
One of the things that makes a product intuitive are mappings. There are many different types of mappings, but the most interesting one Norman discusses is cultural mappings. And the most interesting example of a cultural mapping is the interpretation of the passage of time. In most Western societies, time is static and we are moving forward through it. We also read from left to right, so moving right is analogous to moving forward. Thus when operating a slideshow, clicking the right arrow on the keyboard advances the presentation by one slide. In some other cultures, we are not moving, but instead are experiencing the passage of time like wind blowing in your face. If you imagine this from a side view where you are facing the right, then the time is moving from right to left, and thus it would only make sense to click the left arrow to advance to the next slide. Then there are cultures where the future is behind us, the past is ahead of us, and we are moving backwards*! I think you get the point. Conventions and standards do not persist across cultures. Instead, they contradict each other.
The reason for the mediocre rating is that the last few chapters were a snooze. I felt there was a lot of repeated information that can be summed up as follows: a problem is usually a symptom of a larger issue. Before brainstorming solutions, first consider what the root cause could be. The most successful products solve problems that people didn’t know they had. To quote Henry Ford, “If I had asked people what they wanted, they would have said faster horses."
IRL Update (08/20/2023): Having done lots of back-to-school shopping this weekend, I’ve realised that this book has ruined the way I look at everyday things. I spent a good 5 minutes explaining to my parents how this digital alarm clock from Ikea with completely unnatural mappings was terribly designed. They looked at me like I was crazy and we ended up buying it.
IRL Update (12/07/2024): Adjusted rating up from 7.4 to 8.1, as many concepts from this book have proved helpful in my past 2 co-op terms while designing interfaces for internal users of our products.
*This honestly makes sense. We can see what’s ahead of us (the past), but not what’s behind us (the future). The only reason this idea feels unnatural is that we assume we move “forward” through time, so walking backwards is counterintuitive.