rumination vs self-questioning

rumination

noun
  • Deep thought or consideration. 

  • The act of ruminating; i.e. chewing cud. 

  • Negative cyclic thinking; persistent and recurrent worrying or brooding. 

  • An eating disorder characterized by repetitive regurgitation of small amounts of food from the stomach. 

self-questioning

noun
  • contemplation on one's actions, beliefs, etc. 

How often have the words rumination and self-questioning occurred in a corpus of books? (source: Google Ngram Viewer )