Quantification of individual variation and effects of aging in a speed of human visual information processing.

从视觉系统老化能力退化的角度出发，我研究了老年人在观看短时间呈现的刺激时，如观看运动图像和物体时，视觉信息处理速度的退化。在本研究中，我将重点放在感知部分，并就处理速度如何受年龄影响的个体差异进行了定量研究。在实验中，我用双脉冲法测量了发光和色脉冲响应函数（IRFs）的个体变化和老化效应。在测量彩色irf时，我瞄准了s锥，这是在最接近紫外线的短波长区域具有灵敏度的光感受器。对于S-cone刺激，我测量了个体S-cone混淆线。当两个脉冲以不同的间隔呈现时，我分析了阈值数据，并为每个观察者导出了发光和彩色irf。结果，在16.6 ~ 86.3岁的70（夜光实验）和49（色光实验）上，我成功地推导出了夜光和色光irf。我发现在这个年龄范围内，随着年龄的增长，视觉反应强度在发光反应中降低了49.5%，在色反应中降低了44.2%。另一方面，反应速度的下降基本没有观察到。然而，只有在发光红外光谱的情况下，60%的60岁以上的观察者的反应功能变得更慢，并且没有抑制阶段。这表明，老化效应的补偿机制——信号强度随年龄的下降被求和时间的增加所补偿——只在发光信息通路中起作用，而在色信息通路中不起作用。可以看出，在物体和运动的检测中，发光信息是重要的，而颜色信息则不是很重要。

From the viewpoint of deterioration of ability for visual system by aging, I took up the deterioration of visual information processing speed when elderly people watch stimuli presented in short duration like the case of watching moving images and objects. In this research, I focused on a perception part and investigated an individual variation quantitatively in terms of how the processing speed is affected by aging.In experiments, I measured individual variation and aging effects in luminous and chromatic impulse response functions (IRFs) by a double-pulse method. In measurement of the chromatic IRFs, I aimed at the S-cone that is the photoreceptor having sensitivity in short wavelength region closest to ultraviolet light. For the S-cone stimulation, I measured individual S-cone confusion line. I analyzed threshold data when two pulses were presented with different intervals and derived luminous and chromatic IRFs for each observer.As the results, on 70 (in the luminous experiment) and 49 observers (in the chromatic experiment) in 16.6 - 86.3 years old, I succeeded in derivation of luminous and chromatic IRFs. I found that the intensity of visual response was reduced in 49.5% in the luminous response and 44.2% in chromatic responses by aging in this age range. On the other hand, the decline of response speed was not basically observed. Only in the case of luminous IRFs, however, the response functions became slower and did not have an inhibitory phase in 60% of observers older than 60 years old. It suggests that the compensation mechanism of aging effect, in which the age-related decline of signal strength is compensated by increase of summation time, works only in pathways for luminous information but not in ones for chromatic information. It can reflect that luminous information is important in detections of object and motion but information of color is not very much needed for them.