Excerpt: Aversion therapy uses a number of techniques and stimuli to weaken or eliminate undesirable responses such as deviant sexual behavior and substance abuse. In theory punishment is used to directly reduce the frequency of undesired behaviors through contingent presentation or removal of a stimulus, while aversion, or aversive counter-conditioning, seeks to change the undesirable response indirectly by altering the functions of the discriminative and reinforcing stimuli. In practice this distinction is somewhat blurred, since many aversion procedures have both punishing and stimulus-altering effects
