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Comparison of distance rock tests with school children using standard sloan English letter targets versus modified Landolt C targets

1 May 1992


The distance rock test was first introduced in 1975. Since then there are several studies using the distance rock test at various clinics. So far, English letters have been used as far-near-far targets at 20/80 and 20/25 acuity levels. The tests were administered to children of different age groups. In this study, some aspects of the original Haynes distance rock test such as letter features and target spacing were changed. Specifically, the Landolt Cs were modified and used as new targets in the far-near-far discriminatory tasks. Forty four fourth graders and twenty six first graders were selected for the study. The relative response times of the visual system were measured. The results indicate 1) The fourth graders performed better than the first graders under all possible combinations of the test conditions; 2) Both fourth and first graders called out English letters quicker than Landolt Cs; 3) Fourth graders identified widely spaced Landolt Cs quicker than regularly spaced ones; and 4) Both fourth and first graders called out targets at the 20/80 acuity quicker than those at the 20/25 acuity. Both optometric and psychological factors were considered to explain the students' performance. Automaticity as a function of maturity, practice and learning played a significant role in distance rock responses. Automaticity was shown to be present in distance rock performance since its characteristics were detected in this study. Indications for procedural changes and clinical utilization were also discussed.


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