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.

目的：已有研究表明，弱视受试者可通过知觉学习（Perceptual Learning, PL）显著改善视觉功能。此类研究多聚焦于视觉表现的空间维度，但针对知觉学习对时间维度视觉表现影响的评估工作相对较少。本研究旨在探究：是否可通过简单的闪烁刺激开展知觉学习，以提升弱视受试者的时间视觉功能，且该功能提升是否可迁移至空间视觉功能。
方法：招募6名弱视受试者与6名视力正常受试者，首先开展基线心理物理学空间功能表现评估（包括视力、对比敏感度）、时间功能表现评估（临界融合频率（critical fusion frequency, CFF）测试）、静态与闪烁立体视觉测试，以及电生理评估（视觉诱发电位（VEP））。随后受试者接受5次训练疗程，训练任务采用恒定刺激法，范式与CFF测试类似。完成训练后，受试者再次完成初始的功能表现评估任务。
结果：经时间维度知觉学习训练后，所有弱视受试者的弱视眼时间视觉表现（临界融合频率）均得到提升（平均提升17%，p<<0.01）。研究同时发现，该训练效果可泛化至空间、时空及双眼任务中。电生理层面的结果进一步验证了这一点：弱视受试者的视觉诱发电位振幅升高、信噪比提升至与视力正常受试者无显著差异的水平，且双眼间同步性增强。与之相反，视力正常组未观察到训练带来的显著效果。
结论：本研究结果凸显了知觉学习在改善时间与空间视觉功能方面的应用潜力。未来仍需开展相关研究以优化该方法，使其适用于临床应用场景。