Tag Archives: don norman

Preventing User Errors

One of Jakob Nielsen’s 10 Usability Heuristics concerns user error prevention, and it is perhaps among the most important ones. Having a good design process in place, an understanding of the concept of mental models, and conducting usability tests can uncover potential areas of user error. These can then be addressed through design improvements targeting error prevention.

Two Categories of Errors

In The Design of Everyday Things, Don Norman categorizes errors into slips and mistakes. Slips take place at a subconscious level and occur when an action is not done correctly; you intend to do one thing and end up doing something else. Slips also occur during the execution of a plan or in the perception or interpretation of the outcome. Mistakes are conscious deliberations, they “occur when the wrong goal is established or wrong plan is formed”.

Norman further breaks down slips and mistakes into classes. Let’s look at each of these further. Continue reading

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UX of Sofas

Interior Designer Rose Tarlow is very particular when it comes to sofas, “I never use two seat cushions because three people won’t sit on the sofa…

I didn’t give it too much thought until I ended up with this sofa:

4297-bloom-sofa-anthracite-med-03

Notice it has ONE cushion.  The design offers two affordances: the choice of where to sit and the number of people who can sit. By contrast a traditional three-cushion sofa constrains those choices.  A two-cushion sofa offers ambiguous cues on how many can sit and where they can sit.

In the Design of Everyday Things, Don Norman said;

“…the appearance of the device must provide the critical clues required for its proper operation—knowledge has to be both in the head and in the world”.

So judging by this principle, single cushion sofas are better than three and two-cushion sofas. Though of course those sofas have different affordances like easier clean-ability.