Perceptual control and layered protocols in interface design: I. Fundamental concepts

Perceptual Control Theory (PCT) is a general psychological theory based on the tenet, "All behaviour is the control of perception". Layered Protocol T heory (LPT) can be seen as PCT applied to the special case of communication between cooperating partners, both controlling their own perceptions. PCT and LPT can be applied to the design and analysis of human-machine interfac es, although LPT may be more tractable in many cases. LPT is discussed in t he context of the analysis and redesign of the interaction between a pilot and a Control Display Unit (CDU) in an operational helicopter.