Perceptual Learning Based on a Temporal Stimulus
Description
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.