How did Watson and his wife establish Little Albert's fear of the rat?

Watson and his wife established Little Albert's fear of the rat by associating the rat with loud noises. In their famous experiment, they presented Little Albert with a white rat while simultaneously creating a loud, startling noise that frightened him. This process is known as classical conditioning, where a neutral stimulus (the rat) becomes associated with an unconditioned stimulus (the loud noise) to elicit a conditioned response—in this case, fear.

This pairing led Little Albert to exhibit a fear response toward the rat even when the loud noise was not present, demonstrating how emotional responses can be conditioned. The other methods listed, such as exposing him repeatedly to the rat or using positive reinforcement, do not align with the principles of classical conditioning that Watson employed in his experiment.