Jakob Nielsen’s latest Alertbox post “Bridging the Designer-User Gap” is almost a follow up to the “Myth of the Genius Designer” which I consider one of my favorites from him.
Red emphasis mine.
….There’s a big gap between designers and the majority of users. …. Generally, if you’re a member of a design team, you are not representative of the target audience. I don’t care if you’re the interaction designer, the graphics artist, the information architect, the writer, the programmer, or the marketer. All of these people:
know too much about the product (be it a website, intranet, application, phone, whatever);
are too skilled in using computers and the Web in general; and
care too much about their own baby (so they can’t imaging visitors bouncing after scanning the homepage for 30 seconds — but that’s what outside users do).
– Jakob Nielsen