Final answer:
The goal-directed approach to a stimulus in sign tracking is indicative of operant behavior. A stimulus that is initially neutral can become a conditioned stimulus through classical conditioning, and an innate reaction to a stimulus, like Pavlov's dogs salivating to meat powder, is an unconditioned response.
Step-by-step explanation:
In the context of sign tracking, the organism's approach to the stimulus signaling an appetitive event is goal-directed and resembles operant behavior.
A stimulus that does not initially elicit a response in an organism is a neutral stimulus. When this neutral stimulus is associated with an unconditioned stimulus, it can become a conditioned stimulus through the process of classical conditioning.
The diagram of a cat reacting to footsteps by hiding likely represents an example of classical conditioning, where the cat has learned to associate the sound of footsteps (a conditioned stimulus) with something that prompts hiding (a conditioned response).
Lastly, in Pavlov's experiments, the dogs' salivation in response to the meat powder is an example of an unconditioned response to an unconditioned stimulus.