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September 1950

DISTANCE DISCRIMINATION: VII. Influence of Initial Position of Rods in Howard-Dolman Test

Author Affiliations


Arch Ophthalmol. 1950;44(3):365-369. doi:10.1001/archopht.1950.00910020374003

IN THE Howard-Dolman test of distance discrimination the administrator places the movable rod at some distance either nearer to or farther from the subject than the stationary rod before the subject attempts to aline the rods. This position of the movable rod in relation to the stationary rod is termed an initial position setting. The measure of the subject's distance discrimination is, of course, based on his errors in alining the rods. Because the initial position setting is a fundamental factor in the procedure, the validity of the examination depends on the assurance that the settings exert no significant influence on the subject's errors of alinement. Our observations in administering the Howard-Dolman test, however, have suggested the possibility of such an influence. The purpose of this investigation is to ascertain its presence or absence and to consider the nature of the influence if it does exist.


Method.  —The

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