​​​​​​​Experimental behavior analysis recognizes two procedures that can trigger behavior change: Respondent conditioning and operant conditioning. In response conditioning — more commonly referred to in other theoretical contexts as classical or Pavlovian conditioning — an indifferent stimulus is regularly followed by another stimulus that already triggers a response. As a result of this sequence of events, the first, previously ineffective, stimulus begins to produce a reaction that may have a strong resemblance to the reaction caused by the second stimulus. Although Respondent conditioning plays an important role in learning, especially emotional responses, learning is mostly associated with operant conditioning.