Call an event "just a dumb mistake" or "human error," and you can expect glares and lectures from usability professionals. It's equivalent to telling a teacher "those who can, do, those who can't, teach."
If you've ever been on the receiving end of this cliche, be aware most people do believe in something called "human error" that excuses most "dumb" mistakes. I agree with the field's orthodox opinion that users are never simply dumb.
Instead, they are:
- Busy and multitasking. Your users often will be in a context where they must multitask -- this is otherwise known as "real life." To minimize dumb mistakes, reduce your interface's demands on their attention. List information in familiar ways. Supply everything needed to complete a task on the same page. Consider interruptions: for example, can your users recover from a phone call and still complete their tasks?
- Overloaded with information. Dumb mistakes can result from too many choices, so take care to only show a reasonable amount of relevant info at once. It's not enough to just say "let the user choose." You have to know your users' needs, and design for them a limited number of intelligent choices.
- Hardwired for speed. Humans evolved to make decisions rapidly. Your users are information predators. They'll scent out your relevant links and functions and try them quickly, but they'll be just as quick to lose interest and try something else if the scent disappears. When your workflow includes clear hints at every step, you'll keep users' attention on what's relevant to them.
You want your interface to make users feel smart. Fast. Effective. If your interface makes users feel like "human errors" instead, well who's dumb then?