When should users be made to think?

I've been a little quiet, I know. I've been working hard consulting for an interesting new client on a project that has, yet again, completely consumed my interests with new challenges. In this case, its amazed me that one of the primary concerns of this project has not been to make the interaction as quick and simple as possible, but to produce software that is a) intuitive and b) coerces users into thinking about the appropriate things at the appropriate times.

I've noticed this has become a recurring theme in many scenarios. The first time I heard something along this line was an argument against automating the jobs of pilots, but for making the jobs easier. If pilots get used to the plane doing most of the jobs for them, they may become less capable when the plane malfunctions. However, if the actions are made easier to perform, then the skill is maintained, but the usability has improved.

Search can be considered in a similar way. While lots of search designs are focused on letting users express the knowledge or known constraints that they do have quickly, this can leave users with problems when they have to choose between their results using facets that they have not considered. In this case, we do not at all want to make assumptions, but at the same time, we do not want to leave them to make a decision with only a list of options to do so with.

In some of our previous work we have investigated how giving users example (ideally multimedia) result items that would be associated with each of the items in their new decision. This means that users are become aware of things that the should think about before they buy, AND give them the means to understand the effect of their decisions. Another approach mSpace has taken is to be subjunctive, by allowing users to easily change their mind, or considered another way: rapidly tryout different options by minimising the costs of reversing their decision. To do this mSpace maintains all of the options a user was given at each step, so that the user, with a single click, can switch between different items in the same facet, and see the effect is has on the results.