Magnitude estimation as a psychophysical scaling technique for the perceived difficulty associated with a computer-mediated data-entry task

Date of Completion

January 1992


Psychology, Industrial




The measurement and scaling of the demands imposed by work, or the workload of a task, is a complex issue. This is especially true for tasks which possess greater cognitive than physical demands. With the proliferation of computers in the work environment, the scaling of workload for tasks with a high cognitive component is a timely issue. Although attempts have been made to investigate cognitive workload, the outcome has been many different types of measures, making it difficult to generalize results to other settings. What is needed is a research model to provide a common methodology for the measurement and scaling of the workload associated with cognitive tasks. S. S. Stevens has shown that there is a general law relating stimulus intensity to subjective perceptions of stimulus magnitude for primary and secondary sensations. This study tests the viability of the psychophysical scaling technique of magnitude estimation for scaling the subjective perceptions of the difficulty associated with a computer-mediated data-entry task.^ To test the hypothesis that subjective perceptions of the difficulty associated with a data-entry task can be reliably scaled using magnitude estimation, four female participants entered five and nine digit zip code numbers in a machine-paced data-entry task over ten daily work sessions. Each digit condition was performed for five consecutive sessions. Participants were prescreened for typing ability and trained to criteria prior to the experiment. Twelve separate work rates were tested per daily session and worker's numeric judgments of the perceived difficulty and performance measures were recorded for each rate. These judgments of perceived difficulty per work rate and per digit condition were analyzed individually by participant using regression analysis. Results showed that a power function accounted for a significant portion of the variance relating subjective perception of difficulty to work rate. To test a second hypothesis that different task parameters would influence perceived difficulty, the slopes of the regression functions between digit conditions were compared for each participant. These results were also significant for all participants. It was concluded that magnitude estimation is a reliable method for scaling subjective perceptions of difficulty associated with a computer-mediated data-entry task. ^