This is an example of a negative reinforcement device used in training dogs to stay off furniture. The plastic sheet has embedded wires, which deliver a slight electric shock when the plastic is touched. While not harmful to the animal, the shocks are annoying and cause the animal to avoid the plastic.

The dog learns to avoid the plastic, but not the furniture. This pattern of learning is very typical of negative reinforcement training; the punishment is learned, but the animal fails to form an association between the punishment and the act that the trainer is trying to discourage. The association is between the plastic and the shock, not between the furniture and the shock

Consequently, when the plastic isn't present, the animal uses the furniture as a bed. Longterm experience with the shocking device doesn't lead the dog to generalize from the negative reinforcement to the principle that the trainer is trying to achieve.