An Examination of the Relationship Between Fitts' Law and Schmidt's Law

Jonathan McKeeman, Purdue University


There are two prominent speed accuracy tradeoff relationships; Fitts’ Law and Schmidt’s Law. The Fitts tasks are considered to be spatially constrained, whereas the Schmidt tasks are temporally constrained. In this experiment the relationship between these two speed accuracy tradeoffs was examined. Previous studies have allowed for the hypothesis that these two laws may be related or share similar control processes. Through analysis of the previous literature on the subject I hypothesized that the two speed accuracy tradeoffs are unrelated and do not share a common control process. To test this hypothesis, participants performed both speed accuracy tradeoff tasks under similar parameters in order to compare the tasks on the same scale. For each task the relation between average velocity and effective target width was examined. The two tasks exhibited unique linear relations between speed and spatial accuracy. Based upon this result it was concluded that these two speed-accuracy relations possess a unique non-shareable control process.




Zelaznik, Purdue University.

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