The Transfer of Perceptual Learning Between First- and Second-Order Fine Orientation Discriminations

FirsT- and second-order systems have been proposed to explain visual information processing. With regard to the communications between the two systems, mixed results have been shown. The transfer of perceptual learning between first- and second-order systems was examined in fine orientation discrimination tasks. Observers were either trained with luminance-modulated (LM) orientation and tested with contrast-modulated (CM) orientation (Experiment 1) or trained with CM orientation and tested with LM orientation (Experiment 2). The difficulty of the discrimination of the two types of orientations was equalized. Learning curves were tracked and compared between observers who had training and those who had no training. Results showed that the performance of observers trained with LM orientation improved rapidly in CM task and vice versa, while the performance of untrained observers tended to stay low. This two-way transfer suggests that there are bidirectional communications between first- and second-order systems wherein higher-level cortical areas might be involved and the recruitment of common population of neurons might be playing an important role.