pathological mental process catatonic behaviour Marked motor abnormalities including motoric immobility (i.e., catalepsy or stupor), certain types of excessive motor activity (apparently purposeless agitation not influenced by external stimuli), extreme negativism (apparent motiveless resistance to instructions or attempts to be moved) or mutism, posturing or stereotyped movements, and echolalia or echopraxia. DSM-IV-TR (american Psychiatric Association)