horripilation vs pilomotor reflex

horripilation

noun
  • A real or fancied bristling of the hair of the head or body, resulting from disease, terror, chilliness, etc. 

pilomotor reflex

noun
  • Raised skin, usually caused by the involuntary erection of hairs on the neck or arms caused by cold, excitement, or fear. 

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