出典:Wiktionary
出典:Wikipedia
出典:『Wikipedia』 (2011/05/13 17:56 UTC 版)
Vacuum activities (or vacuum behaviors) are fixed actions of animals, which are triggered by inherited behavior patterns, although the usual key stimulus is absent. This type of behavior shows that a key stimulus is not always needed to produce a behavior. Vacuum activities are hard to identify because it is difficult to determine whether any stimulus triggered the behavior.