"Training Dogs" by Colonel Konrad Most, goes into some detail on this (pg.30). Basically, in involves setting up a scenario with the dog, and chicken in proximity, and applying correction when the dog shows any intrest in the chicken. Enough unpleasant association with the chicken will take out the "Chicken" drive ;) Similar training is useful with cats. True learning is accomplished in the "here and now", so they can redirect this behavior if it's recreated for them in a situation that you can fully control and instantly apply proper correction. Since what the dog's experience of the chicken is, association by smell, sound and motion, this wouldn't fix for cats since they smell, sound and move differently. The "context" is what matters, for how the dog, not the human, "senses" the situation.