Human beings make mistakes, and there are many ways in which we like to do this. However, while they may seem infinitely diverse, almost all of our errors fall into six primary categories, according to psychologist Don Norman in his book “The Design of Everyday Things.” In chapter five, in which Norman explores the truth that “to err is human,” he tackles the task of somehow structuring the messiness of mistake-making:
When two actions have similar “initial stages” and you find yourself doing the more familiar of the two, despite intending to achieve the other. Examples: heading home from work for the first time after moving recently and driving toward your old apartment; opening a new tab and immediately beginning to type the URL of your most frequented site rather than the one you intended to visit.
Performing the right action on the wrong object; occur most frequently when the objects are physically near each other. Example: in taking a sip of water, grabbing the jelly jar on the table rather than your glass; clicking the tab or button right next to the one you actually wanted.
Sensory reactions that, while they may be correct in and of themselves, arrive at the wrong time and interrupt a current process. May also involve the application of the wrong information because it was more readily available. Example: a dog barking at a non-threatening noise; filling in fields incorrectly in a data form.
Associative Activation Errors
You know, subconsciously or consciously, that something should not be said or done, but then, beguilingly, you do. (This is the root of about 70% of Socially Awkward Penguins.) Example: as the barista hands you your drink and says, “enjoy your latte!,” replying, “thanks, you too.”
You think of something you ought to do, take action to complete it, and then, inexplicably, forget to do it once you get there. Example: walking into a room and forgetting why you’re there. Or opening a new tab and forgetting why.
Overriding one use by putting an object into another mode. Example: holding a cup of coffee and then, without thinking, checking the time on your watch, spilling your drink as you turn your wrist. (The error is caused by the “mode” in which you have your wrist.) Also, things like links that do not open in new windows and instead “override” your current page.
How to deal?
Users will work to mitigate – limit – their own mistakes. And while it makes sense to assume a degree of conscientiousness while we go about our daily lives, the reality is that we will mess up. Even in setting out to do the most simple of tasks (say, turn on a light) we often make mistakes (like standing up and walking across the room, only to forget why.)
The designer can help, by creating items, objects and interfaces that lead the user along and validate his or her humanness. The tactics one might employ in anticipating and reacting to mistakes include:
- Assume that every possible mistake can happen and work to prevent them
- Make actions reversible
- Make actions as “cheap” as possible
- Do not require users to hold all information in their head
- Make options apparent
- Make results of actions apparent
- Use constraints – physical, logical, semantic and cultural
- Use forcing functions (example: a car that cannot be locked without using the key, preventing the key from being locked inside)
Above all, we should build with empathy as much as if not more than we build for aesthetics. Think like a human and let “real” (non-designer) humans use the product before you let them loose with it for good. Watch them break it; provide a way for them to back themselves out of corners.