Listen Nassim Taleb in this interview (minute 4) claiming that humans are bad designers:

In his most popular book, “The Black Swan” (nothing to do with the movie), Taleb explains that many disciplines allegedly scientific like sociology, meteorology, politics and especially economics, are so complex and are so hugely affected by single events impossible to foresee (“black swans”), that making valid predictions is useless in most cases. Worse still, we are unaware of how bad we are making predictions.

Obviously, Taleb is not talking specifically about interface design, but it’s inevitable to come to the same conclusion because it’s also true that we are not good at designing interfaces. That’s why every approach to User-Centered Design is iterative: we know we are not going to find a suitable solution at first, so we keep trying and refining until we reach a valid design (because “we are good at discovering things”).

And what are our black swans? Users: it’s impossible to foresee how users are going to react in front of an interface (anyone who has performed or watched a usability user test has realized).

So … what’s the purpose of guidelines, style books, heuristic principles, etc.? Taleb claims that it’s easy to be an expert afterwards, for example, to explain which were the causes of World War I or the current economic crisis, events which may seem now inevitable and completely explainable. But the truth is that, in such complex systems, no one can apply economic principles or political theories to predict that kind of event.

Gestalt laws about perception. Are they useful for creating a design?

So it’s possible that, when designing interfaces, we suffer from a reduced version of the same effect; those design principles, those guidelines, those laws of perception (like Fitts or Gestalt) and those heuristic principles serve as a support to explain, afterwards, why a given design works or not. But we should consider if, as Jared Spool claims, when designing, they just don’t work.