A psychopathological condition characterized by immobility with increased muscle tone. The condition may be accompanied by mutism (see Mutism in Chapter 2.1. Key Psychological Concepts in Clinical Psychology), negativism (see Negativism in Chapter 2.1. Key Psychological Concepts in Clinical Psychology), fragmentary delusional experiences, and verbal pseudo-hallucinations. Catatonic stupor can develop both quickly and gradually, in these cases, slowness, angularity of movements, long freezing in one place, etc., first appear.