Do Dogs Have a Sixth Sense?

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Several years ago I was visiting the laboratory of a colleague who studies the behavior of birds when I observed something that I considered to be spooky. He had two banks of cages in the lab, containing about a dozen-and-a-half white birds. I was discussing an academic issue with him when I suddenly noticed that almost all of the birds were standing in their individual cages with their heads and bodies pointed in the same direction. It was obvious that the birds were not looking at something that they found interesting, since they were looking slantwise away from the open mesh cage door which gave a clear view of the laboratory.

When I asked my colleague what was going on, he smiled and said, "It's fall, and if these birds were out in the wild they would be preparing to migrate back to the south. A bunch of researchers have been able to show that these birds, and many others, have a magnetic sense, so that they can tell where north and south is. So the reason they are all oriented in the same direction is that they are attuned to that magnetic information and are responding to it by facing south."

I then asked him, "Do mammals, like dogs, have a similar magnetic sense?"

"There are people working on that question," he replied, "and they've already uncovered some suggestive evidence that foxes, rats and some kinds of deer may be sensitive to magnetic fields."

About a year or so after that incident I encountered a piece of research which seemed to provide evidence that domestic dogs also perceive the Earth's magnetic fields and even respond to small variations in geomagnetism. The data was subtle, but it demonstrated that under calm magnetic field conditions dogs showed behavior that was influenced by magnetism. Specifically, the researchers looked at when dogs marked their home territory by urinating or defecating. At these times the dogs tended to align their bodies roughly along the north-south magnetic axis. During unstable magnetic field conditions (such as during geomagnetic storms caused by variations in the "solar wind") this directional preference disappeared. While that study seemed to indicate that dogs were responding to magnetism, it left a lot of questions unanswered, such as "What mechanisms allow dogs to detect magnetic fields?" and "How is this ability useful for them?" But I suppose that the question that nagged at me the most as a psychologist was whether the dogs were simply being subtly and unconsciously influenced by these magnetic fields or were they actually perceiving something which they could consciously process and cognitively respond to.

The answer to my question appears in a recent report published by a team of researchers headed by Sabine Martini of the Department of General Zoology at the University of Duisburg-Essen in Essen, Germany. Their reasoning was that if dogs were consciously aware of magnetic fields then this perception could be used to train dogs to make specific discriminations, just like one might train dogs to respond to a particular shape or sound.

The setup sounds a bit strange at first, but it does make sense. The researchers took three large brown glass jars, placed a bar magnet in one, and a brass unmagnetized bar in each of the others. Lids were then placed on the jars to keep out any potential odor cues. The notion was that the magnetic effects would easily pass through the glass and if dogs perceive these in some way then they could use that that information to select the jar containing the magnetized target. As a control condition, three glass jars were used again but this time one of the jars contained a food treat. Once more the jars were sealed and since no odors could escape and the contents of the jar could not be clearly seen it seemed unlikely that the dogs would ever detect the presence of the food contained within.

The positions of the jars were randomly varied from trial to trial and standard clicker training procedures were used—specifically the dogs rewarded with a click and treats when they indicated the jar with the magnet (or on control trials when they found the jar with the food). In the phase of the study where the target was food, as was expected, none of the dogs were able to learn to detect the actual jar containing the food at an above chance level, which is sensible since no clues could escape the sealed jar. However when the dogs were trained to detect the magnetic field, 13 out of 16 detected the magnet at an above chance level. This shows that the dogs were able to consciously perceive something associated with the magnetic field and use it to guide their behavior.

These experiments seem to support the existence of a magnetic sense in dogs, and further, seem to prove that something about the magnetic field is actually registering in the dogs' conscious perception of the world. Why this ability evolved in dogs, and whether this magnetic sense is used in helpful or adaptive ways to guide a dog's behavior both still remain unanswered questions.

Nonetheless, when someone asks "Do dogs have a sixth sense?" we can certainly now answer "Yes": That extra sense is one that detects variations in magnetic fields.

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