irresolution vs perseveration

irresolution

noun
  • Lack of resolution; lack of decision or purpose; vacillation. 

perseveration

noun
  • The tendency to continue or repeat an act or activity after the cessation of the original stimulus. 

  • The act or an instance of persevering; perseverance. 

  • Uncontrollable repetition of a particular response, such as a word, phrase, or gesture, despite the absence or cessation of a stimulus, usually caused by brain injury or other organic disorder. 

  • Argument by repetition; a mantra. 

How often have the words irresolution and perseveration occurred in a corpus of books? (source: Google Ngram Viewer )