Khan Academy Operant Conditioning Questions

Hello all, I've never had problems with operant conditioning; however, I've missed 2 questions from Khan now pertaining to operant conditioning. One has to do with a patient finding relief from pain due to acupuncture and deciding to continue acupuncture as a result. I thought this was an example of positive punishment because acupuncture is being added in order to decrease pain; however they say negative reinforcement because pain is being removed and she decides to keep going to... Khan Academy Operant Conditioning Questions
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums