Abstract
Studies of perceptual learning show a large diversity of effects, with learning rate and specificity varying across stimuli and experimental conditions. Most notably, there is an initial fast phase of within session (online) learning followed by a slower phase, taking place over days, which is highly specific to basic image features. Our results show that the latter phase is highly sensitive to contextual modulation. While thresholds for contrast discrimination of a single Gabor patch are relatively stable and unaffected by training, the addition of close flankers induces dramatic improvements of thresholds, indicating increased gain of the contrast response function ("context enabled learning"). Cross-orientation masking effects can be practically eliminated by practice. In texture discrimination, learning was found to interact with slowly evolving adaptive effects reducing the effects of learning. These deteriorative effects can be eliminated by cross-orientation interactions found to counteract sensory adaptation. The experimental results are explained by plasticity within local networks of early vision assuming excitatory-inhibitory interactions, where context modulates the balance between excitation and inhibition. We suggest that reduced inhibitory effects increases learning efficiency, making learning faster and generalizable. Specificity of learning seems to be the result of experience dependent local contextual interactions.
Meeting abstract presented at VSS 2013