Basic Processes and Individual Differences in Understanding and Using Instructions
Final rept. 15 Jun 1983-15 Aug 1985
BOLT BERANEK AND NEWMAN INC CAMBRIDGE MA
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This project dealt with how people understand and use written instructions in operating a device or assembling an object. In Experiment 1, subjects read and then executed single-step instructions for operating a simple device e.g., Turn the right knob so that the gamma meter reads 20 if the sigma indicator light is on. An instruction was read faster if its topics were mentioned in the order in which they would be executed. This effect, taken together with results due to individual differences in working memory, suggested that understanding an instruction involves instantiating a step schema, i.e., an abstract representation of an instructional step that contains slots for antecedent, action, and consequence information. Experiment 2 used the same materials as the first study, but now the subjects task was simply to memorize each instruction. In Experiment 3, we switched to an assembly task. Subjects has to assemble a model helicopter from instructions that included 72 steps. In Experiment 4, we returned to a device-operation task, but used a more complex device than that used in the earlier studies. Now, we focused on information other than that in the instructions, as the major variable was whether or not subjects had learned a mental model of the device they had to operate. Having a mental model facilitated memory of the device, as well as the time to read an instruction about operating the device, as well as the ability to reason about the device.