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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:
All 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.