Repeatability of the visual manipulation test

Background: The Getman-Henderson-Marcus Visual Manipulation Test (VMT) is a commonly used test of visualization with an objective scoring procedure. However, its repeatability has not been studied. Purpose: The purpose of this investigation was to assess the repeatability of the VMT in children in the second through fourth grades. Method The VMT was administered to the children (n = 193; mean age, 8.72 years) from a middle class elementary school near Columbus, Ohio. One class from each grade (n = 56) was retested by the same optometrist within 1 month. Repeatability analysis included plotting the difference vs. the mean of the scores obtained at the initial test and retest. Results: Ail the children were able to complete the test. Means and SD's were found to be 5.23 +/- 1.98 for second graders, 5.76 +/- 2.10 for third graders, and 6.95 +/- 2.30 for fourth graders. The mean difference between test and retest scores was close to zero. The 95% limits of agreement were found to be -4.5 to 5.2. Conclusion: No consistent learning effect seemed to be present upon retest. However, analysis revealed poor repeatability for the VMT. Therefore, the VMT should not be used to monitor progress with therapy.