The confusion probably comes from the idea that dogs can see better in the dark than humans. This isn’t because of a wider spectrum of sight but mainly because a dog’s eyes contain more rods and can let in much more light than humans. A pitch dark room is still pitch dark to a dog as it is to a human. But a dimly lit room will be easier for a dog to see in. Technically, a human with perfect eyesight is said to have 20/20 vision but a dog’s perfect eyesight is about 20/75 and varies quite a bit from breed to breed. Dog’s have a harder time determining shapes but have a better time recognizing objects based on motion. So when your dog recognizes you it’s not because of your appearance as much as it is your unique motion (and scent).

      The sense of smell is one of the senses where a dog clearly out-ranks humans. The olfactory bulb, the part of the brain used for smelling, is 4 times bigger in dogs than in humans. For the Bloodhound breed it’s even bigger. Because of this, dogs can discriminate a smell at concentrations nearly 100 million times lower than humans can.  Dogs also use their wet noses to determine the direction of the air current that a specific scent is coming from to help them focus their nose that way. Dogs also have a much more acute awareness of natural pheromones and can distinguish specific smells even when they’re combined with other smells. If you were to smell a jar of pasta sauce you would most likely smell the tomatoes and a few other main ingredients within. A dog smelling that same jar of pasta sauce would be able to detect each individual ingredient in the sauce specifically, regardless of how much or how little is in the sauce. They’d also be able to smell the paper and glue from the jar’s label and even detect the scent of those who have handled the jar. This is why the police use dogs to detect things like missing people and smuggled drugs.

      Now when it comes to hearing, dogs are also superior to humans. So if there is a ghost in your house making noise, your dog will likely hear it before you do; especially if the theory is true that spirits are communicating on a wavelength we can’t hear. Humans typical hear sounds from 20 Hz to 20,000 Hz. A dog has a wider spectrum of hearing from about 10 Hz to 100,000 Hz, depending on the breed. For example most dog whistles are between 16 Hz and 22 Hz, which is why a dog hears it and we don’t. A dog also has the ability to hear sounds that are 4 times further away than what humans can hear. Much of this has to do with the biological make-up of a dog’s ears. Most dog breeds have ears that are cone shaped which helps funnel the sound into their hearing canal. A dog’s ears also have 18 different muscles allowing them to move their ears and direct them towards the sound. Dogs also have the ability to sense vibration better than humans which helps them to better determine what or who is causing the sound. Because of these abilities dogs not only can hear better than humans, they can determine what the sound is much more quickly.  While these abilities would - in theory - allow dogs to hear ghosts better than humans, it would also allow them to hear thousands of other natural and man-made sounds that go unheard by humans.

      Like most animals, dogs do have a natural instinct about them. They are able to detect natural disasters like hurricanes, tornadoes, and earthquakes. They can also sense emotions in other animals and especially in humans like fear, anger, sadness, nervousness, injury, danger, sickness, and even pregnancy. Some dogs are even believed to have the ability to detect diseases like cancer in humans. These are phenomenon that we know to exist. The existence of spirits is still unproven, at least scientifically. Thus we can’t conclusively say that a dog can ‘sense’ spirits.

And there is one more difference between dogs and humans that is very important; the brain. A dog’s brain is only one tenth the size of the human brain. And the human brain is made up differently. Humans have the ability of deduction, logic, and thought, while dogs can only learn through repetitive training or through observation. A dog is much more limited when it comes to figuring out what something is especially if they have never encountered it before. So like humans they are quite capable of experiencing pareidolia, the psychological tendency of the brain to perceive something incorrectly, and even more so. As it is true that humans quite often confuse natural or man-made objects or sounds to be paranormal, a dog is even more likely to misidentify something because of their inferior brain capacity.

So what is your dog barking at then? Well just like humans, there could be hundreds of natural explanations for dogs confusing something with being paranormal. There could be a high pitched sound that you can’t hear or a scent that you can’t smell that is causing your dog to act suspiciously. The inaudible hum of the DVD player could be causing Fido to bark at the television. A mouse sleeping in the wall could very well be the reason that Rover is growling in the corner. Or perhaps Benji smells the perfume of a person he used to play fetch with years ago and it’s making him bring his ball to the doorway. The fact is we can’t sense what a dog senses and we don’t know what he is thinking. Quite simply a dog’s actions are no more proof of a spirit than a blinking EMF detector or a chirping motion detector. Like many things you don’t understand, you may be jumping to the conclusion that what your dog is seeing is something paranormal. But until we are actually able to communicate with our dogs, we’ll never know for sure. So the real question is what will happen first; talking dogs or indisputable proof that spirits exist?