“It is an honest question: how smart are your users? The answer may surprise you: it doesn’t matter. They can be geniuses or morons, but if you don’t engage their intelligence, you can’t depend on their brain power.
Far more important than their IQ (which is a questionable measure in any case) is their Effective Intelligence: the fraction of their intelligence they can (or are motivated to) apply to a task.
Take, for example, a good driver. They are a worse driver when texting or when drunk. (We don’t want to think about the drunk driver who is texting.) An extreme example you say? Perhaps, but only by degree. A person who wins a game of Scrabble one evening may be late for work because they forgot to set their alarm clock. How could the same person make such a dumb mistake? Call it concentration, or focus, we use more of our brain when engaged and need support when we are distracted.”
Stephen Turbek, Executive Director of User Experience at Morgan Stanley in New York, thinks the question whether users are smart or stupid, is really irrelevant, introduces the concept of Effective Intelligence instead, and explains how you can design for it.