This test directly measures participants’ visual acuity or distance vision. The participant is seated 12.5 feet away from a computer monitor at eye level, and letters (called “optotypes”) are displayed one at a time on the screen for the participant to identify, using both eyes at the same time, with the participant wearing his/her normal corrective lenses for distance vision (glasses or contact lenses), if worn. As the participant successfully identifies optotypes of a given size, smaller ones appear on the screen, until the computer program ascertains the smallest-size optotype the participant can successfully see. Conversely, the program displays larger optotypes if the participant cannot see the size that is first displayed, until a size that he/she can accurately see is found. For participants ages 3-7, only the letters H, O, T and V are used, and children may point to a laminated card showing the letters if they cannot verbalize or recall the letter names. For participants ages 8 and above, the entire set of optotypes is used, following a common protocol used in professional vision testing. This is the standard binocular visual acuity measure scored in LogMAR units.
No conditions have yet been associated.
Experimental conditions are the subsets of an experiment that define the relevant experimental manipulation.
In the Cognitive Atlas, we define a contrast as any function over experimental conditions. The simplest contrast is the indicator value for a specific condition; more complex contrasts include linear or nonlinear functions of the indicator across different experimental conditions.
An indicator is a specific quantitative or qualitative variable that is recorded for analysis. These may include behavioral variables (such as response time, accuracy, or other measures of performance) or physiological variables (including genetics, psychophysiology, or brain imaging data).
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http://www.nihtoolbox.org/WhatAndWhy/Sensation/Vision/Pages/NIH-Toolbox-Visual-Acuity-Test-.aspxCitation added by CTorgerson about five years ago Citation Profile This page also available as: