Really good blog post by Kathy Sierra about how poor user experiences deplete our cognitive resources.
If your UX asks the user to make choices, for example, even if those choices are both clear and useful, the act of deciding is a cognitive drain. And not just while they’re deciding… even after we choose, an unconscious cognitive background thread is slowly consuming/leaking resources, “Was that the right choice?” […]
If our work drains a user’s cognitive resources, what does he lose? What else could he have done with those scarce, precious, easily-depleted resources? Maybe he’s trying to stick with that diet. Or practice guitar. Or play with his kids.
Great reminder that our designs echo beyond our applications.