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Computerized color-vision test based upon postreceptoral channel sensitivities

Published online by Cambridge University Press:  05 April 2005

E. MIYAHARA ,
J. POKORNY ,
V.C. SMITH ,
E. SZEWCZYK ,
J. McCARTIN ,
K. CALDWELL  and
A. KLERER
E. MIYAHARA
Affiliation:
Department of Psychology, California State University, Fullerton
J. POKORNY
Affiliation:
Visual Science Laboratories, University of Chicago, Chicago
V.C. SMITH
Affiliation:
Visual Science Laboratories, University of Chicago, Chicago
E. SZEWCZYK
Affiliation:
Department of Psychology, California State University, Fullerton
J. McCARTIN
Affiliation:
Department of Psychology, California State University, Fullerton
K. CALDWELL
Affiliation:
Department of Psychology, California State University, Fullerton
A. KLERER
Affiliation:
Department of Psychology, California State University, Fullerton
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Abstract

An automated, computerized color-vision test was designed to diagnose congenital red–green color-vision defects. The observer viewed a yellow appearing CRT screen. The principle was to measure increment thresholds for three different chromaticities, the background yellow, a red, and a green chromaticity. Spatial and temporal parameters were chosen to favor parvocellular pathway mediation of thresholds. Thresholds for the three test stimuli were estimated by four-alternative forced-choice (4AFC), randomly interleaved staircases. Four 1.5-deg, 4.2 cd/m2 square pedestals were arranged as a 2 × 2 matrix around the center of the display with 15-minute separations. A trial incremented all four squares by 1.0 cd/m2 for 133 ms. One randomly chosen square included an extra increment of a test chromaticity. The observer identified the different appearing square using the cursor. Administration time was ∼5 minutes. Normal trichromats showed clear Sloan notch as defined by log (ΔY/ΔR), whereas red–green color defectives generally showed little or no Sloan notch, indicating that their thresholds were mediated by their luminance system, not by the chromatic system. Data from 107 normal trichromats showed a mean Sloan notch of 0.654 (SD = 0.123). Among 16 color-vision defectives tested (2 protanopes, 1 protanomal, 6 deuteranopes, & 7 deuteranomals), the Sloan notch was between −0.062 and 0.353 for deutans and was <−0.10 for protans. A sufficient number of color-defective observers have not yet been tested to determine whether the test can reliably discriminate between protans and deutans. Nevertheless, the current data show that the test can work as a quick diagnostic procedure (functional trichromatism or dichromatism) of red–green color-vision defect.

Keywords

Color-vision testColor-vision deficienciesPsychophysics

Information

Type
Research Article
Information
Visual Neuroscience , Volume 21 , Issue 3 , May 2004 , pp. 465 - 469
Copyright
© 2004 Cambridge University Press

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References

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