Abstract
Eye-transfer tests, external noise manipulations and observer models were used to systematically characterize learning mechanisms in judging motion direction of moving luminance-defined objects in visual periphery (Experiment 1) and fovea (Experiment 2) and to investigate the degree of transfer of the mechanisms of learning from the trained to the untrained eyes. Perceptual learning in one eye was measured over ten practice sessions and subsequent learning in the untrained eye was assessed in five transfer sessions. Learning in the trained eye improved performance in that eye with virtually equal magnitude across a wide range of external noise levels. A mixture mechanism of stimulus enhancement and template retuning accounted for the performance improvements. The magnitude and mechanisms of subsequent learning in the untrained eye were used to characterize the transfer of each learning mechanism — if a learning mechanism is substantially trained and then transferred completely, no subsequent learning would be associated with this mechanism; otherwise, the mechanism would exhibit subsequent learning. The degree of transfer depended on the amount of external noise added to the signal stimuli. In high external noise conditions, learning transferred completely to the untrained eye. In low external noise conditions, there was only partial transfer of learning: 63% in Experiment 1 and 54% in Experiment 2. Subsequent practice in the untrained eye further improved performance via stimulus enhancement in transfer sessions. The results suggest that independent mechanisms underlie perceptual learning of motion direction identification in monocular and binocular motion systems.
Supported by NSF and NIMH.