An assessment is presented of the benefits and limitations of the Laye
red Protocols (LP) model for the analysis and design of user interface
s in the held of consumer electronics. In the assessment a user interf
ace 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 inte
rfaces are mainly caused by deviations from the LP model. It turned ou
t that especially the learnability of an interface is positively influ
enced by a layered organization of user-system interaction in combinat
ion with high-quality E- and I-feedback and optimum similarity between
interaction protocols. (C) 1996 Academic Press Limited