老龄化背景下短时记忆中视觉编码的验证与动态性探究

Verification and Dynamics of Visual Coding in Short-Term Memory under the Background of Aging

摘要: 本研究旨在复刻Posner经典实验，探究老龄化群体短时记忆中视觉编码的存在、时间动态及年龄相关加工差异。实验采用2 (字母类型：AA视觉语音匹配、Aa仅语音匹配) × 4 (时间间隔：0、0.5、1、2秒)被试内设计，招募20名健康老年人(60~75岁)与20名健康青年人(18~24岁)完成字母异同判断任务，对比两组反应时与编码转换规律。结果显示：(1) 同时呈现时，青年组AA反应时显著快于Aa；老年组虽也存在视觉编码优势，但整体反应时显著长于青年组；(2) 随时间间隔延长，青年组AA反应时显著线性增长，1秒后视觉优势基本消失；老年组AA反应时增长更快，0.5秒后视觉优势即明显衰减；(3) 字母类型与时间间隔的交互作用在老年组更显著，老年人视觉编码向语音编码转换更快、衰减更迅速。重复测量方差分析及事后比较支持上述结果。本研究表明，老龄化影响短时记忆视觉编码效率与动态转换过程，老年人视觉编码优势更脆弱、衰退更快，为揭示老龄化对多重编码系统的影响提供实证依据。

Abstract: This study aimed to replicate the classic Posner experiment and explore the existence, temporal dynamics, and age-related processing differences of visual coding in short-term memory among the aging population. A 2 (letter type: AA with visual and phonological matching vs. Aa with only phonological matching) × 4 (time interval: 0 s, 0.5 s, 1 s, 2 s) within-subjects design was adopted. Twenty healthy older adults (60~75 years old) and 20 healthy young adults (18~24 years old) were recruited to perform a letter identity judgment task, and their reaction times and coding transformation patterns were compared. The results showed that: (1) Under simultaneous presentation, the reaction time of AA was significantly faster than that of Aa in the young group; the older group also showed a visual coding advantage, but their overall reaction time was significantly longer than that of the young group. (2) With the increase of time interval, the reaction time of AA increased linearly in the young group, and the visual advantage almost disappeared after 1 second; in the older group, the reaction time of AA increased faster, and the visual advantage attenuated significantly after 0.5 seconds. (3) The interaction between letter type and time interval was more significant in the older group, and the conversion from visual coding to phonological coding was faster and decayed more rapidly in older adults. Repeated-measures analysis of variance and post-hoc comparisons supported the above results. This study confirmed that aging affects the processing efficiency and dynamic conversion of visual coding in short-term memory. The visual coding advantage is more fragile and declines faster in older adults, providing empirical evidence for revealing the impact of aging on multiple coding systems.