Final answer:
In counter conditioning, the unconditioned stimulus becoming 'poisoned' means the association between the conditioned and unconditioned stimuli breaks down, leading to extinction. This results in the gradual weakening and eventual disappearance of the conditioned response in the presence of the conditioned stimulus alone.
Step-by-step explanation:
When working on counter conditioning to a stimulus, the unconditioned stimulus (the food) becoming 'poisoned' refers to the scenario where the unconditioned response (like salivation) generated by the unconditioned stimulus is no longer evident due to alteration or absence of the unconditioned stimulus. This change can lead to extinction, which is the gradual weakening and disappearance of the conditioned response in classical conditioning. For example, if an animal has been conditioned to associate the sound of a bell with food, and then the food is no longer presented with the bell, over time, the animal's response to the bell will diminish.
Extinction occurs when the association between the conditioned stimulus and the unconditioned stimulus breaks down because the unconditioned stimulus is no longer presented alongside the conditioned stimulus. The example provided of the dog, cat, or child, where here a dog's response to the sound of a tone (conditioned stimulus) that had been associated with receiving meat powder (unconditioned stimulus), will weaken if the meat powder is not presented after the tone, leading eventually to the dog no longer responding to the tone alone.