If you were looking for a subject where most people would think, "I live it, so tell me why I have to dive into the scholarly literature on it?" frustration with computers would be pretty high, somewhere in the same category as breathing. However, a combination of things-- a problem with my Bluetooth keyboard pairing with my iPad, an all-day OSX updating marathon, and a regular problem my kids have using our HP printer-- got me thinking about the problem of frustration in the user experience. It seems to me that frustration is one of those things that's common, that everyone experiences, but still can probably surprise you if you look at it closely.
So I started doing some digging, and came across one of my colleagues at Microsoft Research Cambridge, a brilliant postdoc named Helena Mentis. It turns out she did an M.A. thesis on frustrating user experiences. (Of course, there are any number of jokes you could make that (fairly or not) put the words "Microsoft" and "frustrating user experiences" together in the same sentence, but I won't go there.)
Interestingly, she found that frustrations that are most memorable to users occur while the computer is responding to something you've done-- that is, you've clicked on a link and are waiting for it to load in your browser, or hit "Print", etc. (this is what Donald Normal calls the Outcome phase). She also found that the most widely-mentioned sources of frustration
are intrusive and interrupt the cognitive flow of the user. When the user decided on what goal they wanted to achieve they had an idea of the steps that were needed to complete that goal. However, when there was an unanticipated interruption, the user had to compensate for that interruption thus breaking the cognitive flow.
This seems to be an important rule for interface design and responsive systems. Responses of a system should not interrupt the user’s cognitive flow and should not take control away from the user. If there is a system response that could possibly be intrusive, allow the user to easily regain control. These interruptions are remembered by the users and color their perception of the experience of using the system.
Given that frustrating experiences have got to be one of the principal sources of non-contemplative computing experiences, it makes sense to have a couple paragraphs about them in the book.