Final answer:
A trainer may suggest using target sticks or a verbal marker as alternatives to a clicker when training an animal. These methods are based on the principles of classical conditioning, which was demonstrated by Pavlov's experiment with dogs.
Step-by-step explanation:
When working with a client who has been struggling to use a clicker, a trainer may suggest trying target sticks or a verbal marker as alternatives. These methods can be effective in aiding the learning process for the animal. For example, Pavlov's experiments with dogs demonstrated how classical conditioning can be used to create an association between a neutral stimulus (like a sound) and a significant one (like food), resulting in a conditioned response.
As for the other options listed: Collar corrections and shock collars are considered more aversive training methods that could potentially harm the relationship between the trainer and the animal or inflict unnecessary discomfort to the animal. As such, these are often not recommended by modern animal behaviorists who advocate for positive reinforcement techniques.