More recently, neuronal correlates of perceptual learning have been also associated with data recorded from the PPC (Law and Gold, 2008). Because our stimuli (fractal images, see Figure 1) were selected for maximal discriminability in terms of color scheme and shape, low-level perceptual learning resulting in altered activation due to improvement in stimulus detection and discriminability was most likely minimized in our study and cannot account for the SPE signal found in pIPS. However, perceptual learning – in the sense of subtly changed perceptual representations due to reinforcement (Seitz and Dinse, 2007) – may of course be engaged during the task, especially in session 2, although due to the absence of reinforcement in session 1, this explanation is unlikely to account for the state-learning signals observed throughout session 1 and 2.
