 While there are clear cases of long-term experience-induced perceptual changes and clear cases of short-term experience-induced perceptual changes, there may be intermediary cases where it is difficult to tell whether they count as long-term or not. In such cases, in order to determine whether the case is a genuine case of perceptual learning, it may be necessary to look at the mechanisms involved (see  section 2  below on the mechanisms of perceptual learning). If the mechanisms involved are characteristic of other cases of perceptual learning, then that is a reason to count the case as an instance of perceptual learning. If the mechanisms involved are uncharacteristic of perceptual learning, then that is a reason not to count the case as an instance of perceptual learning.