Which item is commonly used as a classically conditioned fear stimulus?

• A. Vacuum cleaner noise
• B. Leash
• C. Food bowl
• D. Car in driveway

Answer: (A)

Classical conditioning relies on a neutral cue becoming a fear trigger when it’s paired with an aversive event. The vacuum cleaner noise is a classic example because its sound is loud, abrupt, and tends to startle dogs, so it reliably evokes fear or arousal. Through conditioning, this sound can come to elicit a fear response on its own, even when no actual vacuum is present, making it a standard, well-understood fear stimulus used in training and behavior studies.

A leash is a handling cue and can become associated with various experiences, but it isn’t inherently a fear-inducing stimulus. A food bowl represents a positive treat and reinforces approach and feeding, not fear. A car in the driveway is a contextual cue that might be linked to routines or arrivals, but it isn’t as universally fear-provoking or as cleanly used as a fear stimulus in conditioning demonstrations as the vacuum cleaner noise.