Abstract
Perceptual learning becomes completely transferrable with double training when the observers receive additional exposure of the transfer stimulus via an irrelevant task. However, we noticed that Vernier learning transferred to a new location after double training only when the training and transfer stimuli shared the same orientation. A second exposure to a suprathreshold orthogonal Vernier was necessary to enable cross-orientation learning transfer (Wang_et_al._2012). Here we investigated whether orientation learning transfer between orthogonal gratings and symmetric dot patterns also requires such triple training (training plus double exposures). Observers learned orientation discrimination of a grating or symmetric dot pattern, and the learning transfer to the other, orthogonal, stimulus was tested. We found (1) Baseline: Grating orientation learning (35°/125°) had little effect on orthogonal dot-pattern orientation discrimination; (2) Double training: Additional exposure to the orthogonal dot patterns via a brightness discrimination task produced incomplete learning transfer to orthogonal dot patterns, since further dot-pattern orientation training induced extra performance gain; (3) Triple training: Observers received exposure of both new orientation and new stimulus via two separate tasks: grating brightness discrimination at the orthogonal orientation, and dot pattern brightness discrimination at the same or orthogonal orientation. After triple training, dot-pattern orthogonal orientation discrimination was improved, and continued training produced no further gains, indicating complete transfer of grating orientation learning to the orthogonal symmetric dot patterns. (4) Control: The above double exposures by themselves had little impact on dot-pattern orientation discrimination. (5) The same patterns of learning transfer results were replicated from dot-patterns to gratings. These results suggest that the brain performs two remapping to transfer perceptual learning. One remaps learning to an orthogonal orientation of the same stimulus, which is enabled by exposure of the same but orthogonal-oriented stimulus. The other remaps learning to a physically distinct stimulus by exposure of the new stimulus.
Acknowledgement: Natural Science Foundation of China Grant (31470975 & 31230030