This test is a measure of gaze stability during head movement, which helps identify individuals who may have a deficit of the vestibular system (which regulates internal balance). First, the NIH Toolbox Visual Acuity Test must be administered, followed by the DVA Test. Participants are again seated 12.5 feet from a computer monitor at eye level. For the DVA Test, participants wear lightweight headgear that contains a rate sensor and are asked to move the head back and forth, as if indicating “no.” Once the head is measured to be moving at greater than 180 degrees per second by the rate sensor, an optotype flashes on the monitor, and the participant is asked to identify it. As with the Visual Acuity Test, only the letters H, O, T and V are used for ages 3-7, while ages 8+ use the entire letter set. Smaller optotypes are displayed as the participant correctly identifies letters, and larger ones are displayed if the participant cannot correctly identify the letter shown, until the computer has calculated the smallest size that the participant can see with the head moving. This is calculated separately for head rotation leftward and rightward from center (though the participant continues shaking the head both ways), and this performance is compared to the participant’s visual acuity when the head was stationary (the NIH Toolbox Visual Acuity Test score, sometimes referred to as “static” visual acuity in the context of the DVA test). The difference between static and dynamic visual acuity represents the vestibular contribution to gaze stability. DVA scoring, as with visual acuity, is based in LogMAR units
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/Vestibular/Pages/NIH-Toolbox-Dynamic-Visual-Acuity-Test-.aspxCitation added by CTorgerson about four years ago Citation Profile This page also available as: