Layered protocols : hands-on experience

An assessment is presented of the benefits and limitations of the Layered Protocols (LP) model for the analysis and design of user interfaces in the field of consumer electronics. In the assessment a user interface of an existing digital audio recorder which is only partly in line with the LP model is compared with an interface designed according to the model. The observed differences in usability between the two interfaces are mainly caused by deviations from the LP model. It turned out that especially the learnability of an interface is positively influenced by a layered organization of user-system interaction in combination with high-quality E- and I-feedback and optimum similarity between interaction protocols.