Using One-Dimensional Task Error Measures to Assess Performance on Two-Dimensional Tasks: Comment on 'Attentional Control, Distractors, and Motor Performance'

Abstract

Quantifying the accuracy and consistency of human motor performance has often involved calculating various error score measures of an individual's performance across a block of trials. Traditionally, error score measures have been used for tasks in which performance can vary in only one dimension. However, recent studies have used these error measures with more complex tasks, in which performance may deviate on the horizontal and vertical axes of a two-dimensional surface. This article examines the use of these one-dimen- sional task error measures for performance on two-dimensional tasks, with special attention to a recent article by Singer, Cauraugh, Murphey, Chen, and Lidor (1991). We show that using one-dimensional e m r scores to assess perfor- mance on a two-dimensional task may yield results that are arbitrary and thus difficult to interpret in a meaningful way.