Acts are defined as complicated behavior patterns usually involving some goal accomplishment. Acts are made up of many individual movements.
Movements are specific responses to specific stimuli.
Acts are composed of muscular contractions that are the response to specific stimulus and are not dependent upon practice. But the learning of an act does depend on practice. Learning an act requires practice so that the proper movement is associated with its own cues. Once acquired, associations are permanent but they may not appear in every performance due to weak associations. These weak associations cannot be retrieved because of strong interference from other associations.