Final answer:
Stimulus discrimination occurs when an organism learns to respond differently to two distinct stimuli, eliciting a conditioned response from one and not the other.
Step-by-step explanation:
Stimulus discrimination occurs when two stimuli are clearly different and one brings on a conditioned response but the other one does not. This learning process is crucial for organisms, including humans, to respond appropriately to various stimuli. An example of stimulus discrimination is when Pavlov's dogs responded to the tone predicting food but did not respond to other non-food-related sounds like a doorbell. This is because the dogs learned to discriminate between sounds that predicted food and those that did not. Similarly, in humans, a cancer patient may learn to feel a specific response to an oncologist rather than to other doctors if the conditioned response has been established with the oncologist's visits due to classical conditioning.