Understanding Instructions: The Role of Explanatory Material.

Abstract : This research deals with how people understand, execute, remember, and use written instructions. The issue of major concern is the organization of steps in a set of instructions. Typically, instructional steps are organized linearly, i.e., instructions consist entirely of a sequence of steps to be executed. Theoretical considerations based on text-processing research, however, suggest that performance would be better if instructions also included some higher-level, hierarchically-organized, explanatory material, where such material serves as a rationale for each executable step. To test this, three different sets of instructions for assembling an electrical circuit were composed. In Experiment 1, steps were read faster, executed somewhat more accurately, and recalled more accurately with Structural and Functional instructions than with Linear ones. Experiment 2 replicated the reading-speed and execution-accuracy advantages for the Structural and Functional instructions, and also suggested that Functional instructions might be superior to Structural ones with regard to answering the conceptual-troubleshooting questions about the circuit and reconstructing the circuit. A secondary concern of the research has been with the content of specific steps. Typically, the time needed to read and to execute a step increased with the number of kernel ideas or propositions in the steps. In addition, steps differ in importance (the more important ones involving major components or their interconnections). While importance affects both reading time and recall, it had no effect on execution, the latter being sensitive primarily to manual requirements.