FACTORS IN PHSIOLOGICAL OPTICS ON VISUAL FATIGUE IN DISPLAY WORK

实验一采用阶跃、正弦、斜坡、斜坡函数等不同波形的闪烁背景刺激，测量阈值增量。在低闪烁频率下，增量独立于背景刺激的波形正弦地变化，这表明第一傅立叶分量是最重要的因素。在高频率下，增量随机波动。在CFF以上，受试者看不到感知闪烁，增量阈值与等亮度的稳定背景上的阈值不同。实验II将一个目标字母图案叠加在不同色度和亮度的噪声字母图案上，测量了两种大小和两种持续时间的刺激对目标字母的识别正确率。一个字母是白色，另一个是红色、绿色、黄色或蓝色。对于所有受试者，当目标与噪声处于相等亮度和/或相等亮度时，发现正确百分比降低。在等亮度条件下，除黄色与白色的识别率基本相同外，其他颜色的识别率均高于白色。这些颜色效应随着刺激的大小和持续时间而增加。实验11的结果表明，目标和噪声（或背景）的亮度和/或亮度相等的条件是显示工作中识别目标字母的不理想条件。

In Experiment I, increment threshold was measured on flickering background stimulus of which waveform was one of step, sinusoidal, on-ramp, or off-ramp function. At low flicker frequencies, increments vary sinusoidally independent from the waveform of background stimulus suggesting that the first Fourier component is the most important factor. At high frequencies, increments fluctuate randomly. Above CFF, where subject does not see perceptual flicker, increment threshold differs from that on steady background of equal luminance. It suggests that some kind of transient responses occur in visual pathway, even though the stimulus looks steady.In Experiment ll, a target letter pattern was superimposed on a noise letter parrern of different chromaticity and luminance, and the percent correct in recognition of the target letter was measured for two stimulus sizes and two durations. One letter was white and the other was one of red, green, yellow, or blue. For all subjects, decrease of percent correct was found where the target is in equal luminance and/or equal brightness with the noise. At equal luminance condition, recognition of colored stimulus is easier than white one except yellow which is almost same as white. These color effects increase with stimulus size and duration. The results of Experiment ll showed that condition where target and noise (or background) are equal luminance and/or brightness is undesirable condition for recognizing a target letter in display work.