周辺視における明るさの羃関数とEqual Brightness Contour 暗・明順応下での比較

苧阪 直行

doi:10.4992/jjpsy.50.1

BRIGHTNESS POWER FUNCTION AND EQUAL BRIGHTNESS CONTOUR FOR DARK- AND LIGHT-ADAPTED EYE IN THE PERIPHERAL VISUAL FIELD

NAOYUKI OSAKA

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JOURNAL FREE ACCESS

1979 Volume 50 Issue 1 Pages 1-8

DOI https://doi.org/10.4992/jjpsy.50.1

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Published: May 20, 1979 Received: August 28, 1978 Available on J-STAGE: July 16, 2010 Accepted: - Advance online publication: - Revised: -
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Date of correction: July 16, 2010 Reason for correction: - Correction: TITLE Details: [in Japanese]

Date of correction: July 16, 2010 Reason for correction: - Correction: SUBTITLE Details: [in Japanese]

Date of correction: July 16, 2010 Reason for correction: - Correction: ABSTRACT Details: Wrong : The hypothesis that the equal brightness contour at detection threshold runs parallel with the contour at supra-threshold were tested both for dark- and ligth-adapted eyes (Fig. 1). The hypothesis assumed was that the exponent of the brightness power function and the zero brightness contour at threshold are both independent of eccentricity. Perceived brightness changed as power functions of luminance in the periphery for dark- and light-adapted eye: Ψ=k(Φ-Φ_t)^β, where Ψ, k, Φ, Φ_t, and β represent perceived brightness, scaling constant, luminance, detection threshold, and exponent, respectively (Fig. 2 and 4). The method of magnitude estimation and the staircase procedure were employed for estimating brightness and threshold, respectively. The luminance was changed from 43 to 83dB re 10^-6cd/m² in 10dB steps and the adapting luminance was set 53dB for light-adaptation. Exponents and detection thresholds of the brightness power functions were estimated across the retinal surface. Applying power functions, equal brightness contours were estimated across the peripheral visual field: 0°, 10°, 20°, 30°, 40°, 50°, 60°, and 70° in the temporal field along the horizontal meridian of the right eye (Fig. 3 and 5).
The results indicated that (1) exponent of the power function gradually increased from .37 to .73 as retinal eccentricity and adapting luminance increased (Table 1). (2) For dark-adapted eye, equal brightness contour decreased as eccentricity increased at supra-threshold levels whereas the contour abruptly decreased at 20° periphery then increased as eccentricity increased up to 70° at threshold levels. On the other hand, for light-adapted eye, the contour was found to be partially parallel except for the fovea (Fig. 6). Thus, in general, the parallel shifting hypothesis could not be supported both for dark- and light-adaptation conditions. A possible underlying brightness mediating mechanism for rod/cone system was discussed.
Right : To test whether the equal brightness contour at supra-threshold runs parallel with the contour at threshold, magnitude estimation and the staircase procedure were employed for estimating brightness power function under dark- and light-adaptation. The luminance was changed from 43 to 83 dB re 10^-6 cd/m² with the light adapting luminance at 53 dB. The retinal loci tested were 0° to 70° periphery in steps of 10°. The exponent of the power function gradually increased from .37 to .73 as eccentricity and adapting luminance increased. The equal brightness contour decreased for dark-adaptation and increased for light-adaptation as eccentricity increased at supra-threshold but at threshold did not follow the parallel hypothesis for both adapting conditions.

Date of correction: July 16, 2010 Reason for correction: - Correction: TITLE Details: [in Japanese]

Abstract

To test whether the equal brightness contour at supra-threshold runs parallel with the contour at threshold, magnitude estimation and the staircase procedure were employed for estimating brightness power function under dark- and light-adaptation. The luminance was changed from 43 to 83 dB re 10^-6 cd/m² with the light adapting luminance at 53 dB. The retinal loci tested were 0° to 70° periphery in steps of 10°. The exponent of the power function gradually increased from .37 to .73 as eccentricity and adapting luminance increased. The equal brightness contour decreased for dark-adaptation and increased for light-adaptation as eccentricity increased at supra-threshold but at threshold did not follow the parallel hypothesis for both adapting conditions.

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