Events that trigger a strong fear response are likely to create a new association to whatever signals your dog perceived in that event (these experiences are stored to long-term memory immediately). Any number of otherwise neutral things can become “bad” to your dog if something scary happens at the exact moment the sight, sound, or smell is perceived. This is why the use of pain or threats in training is like playing Russian roulette with your dog’s behavior. Even if just coincidental, he might pair up a random smell or sight as related to the scary or painful event. He might develop a superstitious fear of water bottles because he got squirted for barking too much. He could run and hide under the bed when the doorbell rings because he was chastised one time a little too harshly for jumping up on your guest. Assuming he will associate his “crime” with the “punishment” is a mistake, when any number of signals in the environment could randomly get paired up with the “bad” thing. It’s important that you remember how scary things can create a powerful negative reaction in the future.

Environment

Your dog’s environment changes moment to moment, and his responses to sensory cues (and your cues) will depend on what is happening around him. What is meaningful in one set of circumstances is not meaningful in another; the environment sets the limitations and possibilities for learning. Sometimes your efforts at change will be swimming against the tide because the environment is constantly reinforcing the original idea. For example, in a home where a man is threatening to your dog, it is futile to try to teach the dog to not be scared of men.

Genetics

Your dog is genetically wired to find things like garbage, your lunch, poop, and other animal scents, including olfactory cues like those from hormones, as potentially meaningful opportunities. He is also instinctually conditioned to recognize certain events as threatening. People frequently trigger defensive behavior from dogs by accident. A few common examples are leaning over an unfamiliar dog to deliver a hug, or trying to retrieve the steak back from the clutches of his mouth after he swipes it from our plate. These actions make sense to us, but they can have totally different meanings to your dog. We are unaware of any reflexive reaction we might trigger from the dog in response to what he perceives as a threat to his personal space or his yummy prize. Depending on his genetic group, your dog might also find fast-moving objects, small mammals, the presence of a predator, or large game particularly meaningful—or, in contrast, not meaningful at all.

Self

What your dog experiences as meaningful will change as he develops (sexually mature male dogs find certain hormonal smells very meaningful, whereas immature female puppies would filter them out). Your dog’s health will also affect the acquisition or loss of meaning ascribed to a certain event (the favorite ball that he spent hours a day chasing might suddenly become invisible to him when he is sick). When he’s older and experiences some loss of cognitive function, he might not recognize the difference between the carpet and the pee pads anymore. Throughout the course of his life, your dog’s internal state plays a powerful role.