Figure 1. Processing during VPL training.
According to the model presented, visual perceptual learning (VPL) of the presented visual feature occurs when a bottom-up signal from the feature is boosted by attention (left) or by reinforcement signals (right). Attention enhances task-relevant signals and inhibits task-irrelevant signals, leading to task-relevant VPL. By contrast, reinforcement signals are diffusive and enhance signals from any stimulus feature presented in the visual field, irrespective of whether the feature is task-relevant or task-irrelevant.