认知与发展心理学研究室知识库

人类已经进入“老龄化”社会，人口老龄化带来严重的社会经济问题。老化引起的功能退化几乎涉及所有认知系统，但具体退化特性及确切神经机制尚存在很大争议。本研究运用心理物理学、模型分析等技术方法，综合研究分析正常老化引起的视觉功能衰退特性、机制并探讨可能的功能恢复途径等问题。
本研究分为三个部分。第一部分为老年视觉功能衰退特性研究，我们建立了视觉功能测试库，系统全面评估了各项视觉功能衰退之间的关系、视觉功能衰退与高级认知功能的之间的关系以及视觉功能衰退对日常生活质量的影响特性。第二部分为视觉功能衰退的心理物理学机制研究，验证了有关老化的噪音假说。第三部分探索了应用知觉学习方法改善老年视觉功能的可能性。结论如下：
一、老年视觉功能衰退特性表现在1）不同视觉功能衰退程度不同，各种视觉功能的损害相对高级认知功能的损害程度更小；视觉功能衰退程度之间，视觉功能衰退与高级认知功能衰退之间具有一定的相关性；2）相比于年轻人，老年视觉功能之间的关联模式增强，体现在各种视觉功能之间、视觉功能与高级认知功能之间，各种高级认知功能之间相关性增强；3）老年人各种视觉功能之间的相互解释性和视觉功能对高级认知功能的解释性显著增强；4）有用视野是区分青年和老年组别的关键指标，分类正确率高达 98.3%；5）视觉功能衰退对日常生活质量的影响主要表现在近距离活动和远距离活动。
二、老年人空间对比敏感度的损害是由知觉模板增益和内部加法噪音的升高共同导致的，具体机制与空间频率相关；知觉模板增益表现在所有测量频率上，内部加法噪音的升高表现在更高频率上。结果部分支持有关老化的噪音假说。
三、在截止频率上对老花眼进行连续 10 天的知觉训练，可以显著提高训练眼在训练频率上的对比敏感度，效果可以传递到非训练频率（即具有频率传递）和非训练眼（即具有眼传递）。训练后，裸眼视力具有显著改善（平均 1.4 行 ）。功能提高主要由神经处理信息能力改善引起，而非光学系统的改变。  
本工作加深了我们对老化导致的视觉功能衰退特性及机制的了解，为探索视觉功能衰退的可能恢复途径提供一定的实验依据，还可为其他病理性老化的相关研究提供一定借鉴。

Population aging is taking place in every country in the world, which would cause far-reaching socioeconomic consequences. Ageing affects almost all cognitive systems, but  the exact characteristics and mechanisms of the resulting functional degradation are still missing.  In the current study, by combining psychophysics and computational modeling, we investigated pattern(s)  of age-related visual  declines, psychophysical mechanism,  and  the  potential  of perceptual learning in recovering degraded functions.  
The experimental research consisted of  three studies. In Study 1, we built a test battery of visual functions and systematically evaluated the relationship among visual functions, visual  declines, visual declines  and higher cognitive functions,  and  the influence of visual declines  on the quality of daily life.  Study 2  focused on the psychophysical mechanisms  (e.g. hypothesis of noise elevation)  of visual declines. Study 3  was  to explore the potential  of training at cutoff spatial frequency in improving contrast sensitivity and visual acuity in old population.  
We found that 1) aging affects most but not all visual functions; The magnitudes of visual declines varied across tested functions; There are correlations between some of the age-related declines and between visual and cognitive declines;  2)  the associative  pattern  (both number of correlation and the magnitude of correlation) among the tested functions were enhanced in old adults; 3) the mutually explanatory power  among  visual functions  and  among  visual functions  and  cognitive functions was significantly elevated in the elderly; 4) the useful field of view (UFOV) was the critical  index function  to distinguish between young and old  (98.3%); 5)  The age-related visual deficits significantly affected near and far activities in daily life.  
The degradation  of spatial contrast sensitivity function was attributed to the decrease of template gain at all spatial frequencies and increase of internal noise at higher spatial frequencies in the visual system, which partly supported the noise hypothesis.
Perceptual learning paradigm that targets  high frequency deficits  in contrast sensitivity  in  presbyopia significantly  improved contrast sensitivity at the trained spatial frequency. Moreover, the effect transferred to contrast sensitivity over a wide range of spatial frequencies and visual acuity in both eyes. The improvements were not due to improved optical transmission.
The relative results will help to understand the pattern and mechanisms of visual ageing, provide theoretical basis of visual rehabilitation in the aged, and shed light upon researches in pathological aging.