Perceptual learning is often orientation and location specific, which may indicate neuronal plasticity in early visual areas. However, learning specificity diminishes with additional exposure of the transfer orientation or location via irrelevant tasks, suggesting that the specificity is related to untrained conditions, likely because neurons representing untrained conditions are neither bottom-up stimulated nor top-down attended during training. To demonstrate these top-down and bottom-up contributions, we applied a “continuous flash suppression” technique to suppress the exposure stimulus into sub-consciousness, and with additional manipulations to achieve pure bottom-up stimulation or top-down attention with the transfer condition. We found that either bottom-up or top-down influences enabled significant transfer of orientation and Vernier discrimination learning. These results suggest that learning specificity may result from under-activations of untrained visual neurons due to insufficient bottom-up stimulation and/or top- down attention during training. High-level perceptual learning thus may not functionally connect to these neurons for learning transfer.
Bibliographical noteFunding Information:
This research was supported by a Natural Science Foundation of China Grant 31230030 (CY). We thank the helpful comments and suggestions from Fang Fang, Sheng He, Stanley Klein, Wu Li, Shin Shimojo, Rufin Vogels, and Li Zhaoping during various stages of this study.
© Xiong et al.