 Perceptual learning involves changes in perception that are long-term. This long-term criterion rules out some cases of cognitive penetration, that is, cases where one’s beliefs, thoughts, or desires influence one’s perception (see Macpherson 2012: 24). For instance, to borrow a case from Susanna Siegel (2012), if Jill sees Jack as angry because she just now believes Jack is angry, this need not be a case of perceptual learning, since it need not be a long-term change. After all, if Jill changes her belief that Jack is angry shortly after, she will no longer see his neutral face as angry. It would be a short-term change in her perception, not a long-term one. And so it would not be a case of perceptual learning.