Some of the stimulus features that are present in a public stimulus may also be present in a private stimulus. These are most likely to be features that are either geometrical, temporal, or intensive. When private stimuli have these properties and the individual has already learned to respond to these properties when they are part of a public stimulus, the response is likely to be extended to the private stimulus. This type of extension can be any of the three categories already discussed: generic, metaphorical, or metonymical.