Classical Conitioning (also Pavlovian or Respondent Conditioning) is a form of associative learning that was first demonstrated by Ivan Pavlov . The typical procedure for inducing classical conditioning involves presentations of a neutral stimulus along with a stimulus of some significance. The neutral stimulus could be any event that does not result in an overt behavioral response from the organism under investigation. Pavlov referred to this as a Conditioned Stimulus (CS). Conversely, presentation of the significant stimulus necessarily evokes an innate, often reflexive, response. Pavlov called these the Unconditioned Stimulus (US) and Unconditioned Response (UR), respectively. If the CS and the US are repeatedly paired, eventually the two stimuli become associated and the organism begins to produce a behavioral response to the CS. Pavlov called this the Conditioned Response (CR).