Perceptual Learning Based on a Temporal Stimulus

Purpose: Studies have shown that amblyopic subjects can greatly benefit from Perceptual Learning (PL) to improve visual functions. The focus of these studies has mainly been on the spatial aspect of visual performance; however, less work has been devoted to evaluate the effect of PL on temporal performance. Here we aimed at determining whether a simple flickering stimulus can be utilized in PL to enhance temporal function performance and whether enhancement will transfer to spatial functions in amblyopic subjects. Methods: Six amblyopic and six normally sighted subjects underwent an evaluation of baseline psychophysics spatial function performance (VA, contrast sensitivity), temporal function performance (critical fusion frequency (CFF) test), static and flickering stereopsis test, and an electrophysiological evaluation (VEP). Next, the subjects underwent 5 training sessions, which included a task similar to the CFF test using the method of constant stimuli. After completing the training sessions, subjects repeated the initial performance evaluation tasks. Results: All amblyopic subjects showed improved temporal visual performance (CFF) in the amblyopic eye (on average, 17%, p<<0.01), following temporal PL. Evidence for generalization to spatial, spatio-temporal, and binocular tasks was also found. The results were further electrophysiologically manifested by an increase in VEP amplitude, increased SNR in amblyopes to levels not different from normally sighted subjects and increased inter-ocular synchronization. In contrast, no significant effect of training was found in the normally sighted group. Conclusions: These results highlight the potential of PL to improve the temporal and spatial visual performance. Future work is needed to optimize this method for clinical applications.

**研究目的**：已有研究证实，弱视受试者可通过知觉学习（Perceptual Learning, PL）大幅改善视功能。既往此类研究多聚焦于视觉表现的空间维度，而针对知觉学习对时间维度视觉表现影响的评估工作相对匮乏。本研究旨在明确：简单闪烁刺激能否应用于知觉学习以提升弱视受试者的时间功能表现，且该功能提升是否会向空间功能发生迁移。
**研究方法**：招募6名弱视受试者与6名视力正常受试者，首先对其开展基线心理物理学空间功能评估（含视力（Visual Acuity, VA）、对比敏感度）、时间功能评估（临界融合频率（Critical Fusion Frequency, CFF）测试）、静态与闪烁立体视测试，以及电生理评估（视觉诱发电位（Visual Evoked Potential, VEP））。随后受试者完成5次训练疗程，训练任务采用恒定刺激法，范式与CFF测试相似。训练结束后，受试者重复完成初始的功能评估任务。
**研究结果**：所有弱视受试者在接受时间知觉学习后，弱视眼的时间视觉功能（CFF）均得到改善（平均提升17%，p<<0.01）。同时还发现功能改善可向空间、时空及双眼任务泛化。电生理层面的结果进一步验证了该效应：弱视受试者的VEP波幅升高、信噪比（Signal-to-Noise Ratio, SNR）提升至与正常视力受试者无显著差异的水平，且眼间同步性增强。与之相对，正常视力组未观察到训练带来的显著效果。
**研究结论**：本研究结果凸显了知觉学习改善时间与空间视功能的潜在价值。未来仍需开展相关研究以优化该方法，使其可应用于临床场景。