as if vs at first sight

as if

intj
  • Refers to something that the speaker deems highly unlikely. 

conj
  • As though; in a manner suggesting. 

  • In mimicry of. 

at first sight

prep
  • Superficially, without a full inspection. 

How often have the words as if and at first sight occurred in a corpus of books? (source: Google Ngram Viewer )