The Collaborative International Dictionary of English v.0.48:

Automatism \Au*tom"a*tism\, n.
   The state or quality of being automatic; the power of
   self-moving; automatic, mechanical, or involuntary action.
   Specifically: (Metaph.) A theory as to the activity of
   matter.
   [1913 Webster]

WordNet (r) 3.0 (2006):

automatism
    n 1: any reaction that occurs automatically without conscious
         thought or reflection (especially the undirected behavior
         seen in psychomotor epilepsy)