confusion vs perplexity

confusion

noun
  • The state of being confused; misunderstanding. 

  • The act of mistaking one thing for another or conflating distinct things. 

  • A lack of clarity or order. 

  • Lack of understanding due to dementia. 

perplexity

noun
  • The state or quality of being perplexed; puzzled or confused. 

  • Something that perplexes. 

  • In information theory, a measurement of how well a probability distribution or model predicts a sample. 

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