An interesting, forthcoming study on the interaction between prototype format and control labeling in consumer products:
In their upcoming article in the journal Applied Ergonomics, Juergen Sauer and his co-authors compare the effectiveness of 2D (e.g. paper) prototypes to 3D products in evaluating usability and performance issues. The authors' meta-analysis reveals that the inherent limitations in 2D prototypes typically limits their application to usability testing - for example clarity of control labels. Consequently, they set out to determine "to what extent user behaviour with a 3D consumer product can be predicted from user behaviour with a 2D paper prototype."
The study examined user temperature and pressure settings for an actual power washer (arguably, not a 3D prototype) and 2D control settings prototypes. As a second factor, different control label types (click on image detail, above) were used including standard numerals, and then two types of "enhanced labeling": substance-oriented (e.g. mud, grease) and object-oriented (e.g. tire, window).
Enhanced labeling influenced users for both the paper and real-world products - for both types of prototypes users would use the control label as a guide to task-appropriate settings. On the other hand, in the case of the numerical labeling, paper prototype users were much more likely to adjust the standard settings, whereas the real product users did not adjust the temperature as frequently. The authors suggest an effort hypothesis as one possibility to explain the results. In the case of the paper prototype, the relative effort and motivation to make changes is relatively small and consistent; whereas in actual product use greater effort is typically required. When task-specific, enhanced, labeling is provided, there is significant motivation and cues to make changes in the actual product that were not available when relying only a numerical scale.
So what does this all mean? Among other things, motivation and effort need to be considered as key factors in user's decision-making process when using real-world products that require physical effort. Making design decisions, even about control labeling, based solely on paper prototypes, is risky. This is probably less so, but not irrelevant, for on-screen interfaces, where less physical effort is required.
Designing interactive consumer products: Utility of paper prototypes and effectiveness of enhanced control labelling
Applied Ergonomics, Volume 39, Issue 1,
Juergen Sauer, Holger Franke and Bruno Ruettinger http://lib.bioinfo.pl/pmid:17498642
