Going round in circles? It's all in your head

Without navigation aids, people trying to walk through forests or other landscapes inevitably end up going in circles. Hikers, campers and other outdoor recreationists are especially vulnerable to "circular walking", because they often stray into wilderness areas not previously encountered.

According to new research by Jan Souman of Max Planck Institute, when few or no external cues are discernible, people attempting to move in a straight direction soon circle. Some circle to the left; some to the right. Some alternate. But the end result is that in the absence of the sun or other orientation aids, people are incapable of maintaining a straight course.

According to Michael Kahana at the University of Pennsylvania, the human brain is wired to detect direction, but for some reason, that wiring does not function. Similar wiring in the brains of monkeys, mice, rats and fish successfully accomplishes direction-finding. Some scientists suspect that humans might have had an ancestral ability to navigate through unfamiliar terrain, but have since lost it.

Tests confirm that people are lousy at navigating unaided through areas with which they are not familiar. Several studies show circling initiates after people travel only about the length of a football field from a point of origin. Research by Roberta Klatsky at Carnegie Mellon University shows blindfolded people veer significantly from a straight course after having moved only about half the length of a football field.

In overcast conditions, people in forests often begin circling within 20 metres of where they started out. In one study, individuals ended up walking facing the original direction of travel within a few hours.

Souman confirms that although people think they are walking in a straight line, in fact, the actual direction shifts rapidly from straight ahead.

Scientists are not sure why humans, unlike most other animals tested so far, are so disoriented when they find themselves in surroundings they do not recognize. Research at the University of Auckland and California Institute of Technology shows that pigeons whose eyes are fitted with frosted lenses that prevent vision can successfully navigate hundreds of kilometres to within 0.5 km of their loft. Other animals are credited with similar feats.

Many do so by means of magnetite particles linked with ion channels that can detect magnetic field directions.

The first conclusive evidence of navigation by means of magnetism surfaced in 1995, in turtles. Since then, similar capabilities have been confirmed in whales, tuna, butterflies, dolphins, frogs, worms and migratory birds. According to Adrian Muxworthy of Imperial College, even lowly bacteria can use magnetic cues to navigate through sediment.

Recent studies show that cattle and deer often forage in patterns consistent with magnetic lines of force in the Earth's crust.

Circular movements are fairly common in non-humans. Several studies show that sleeping ducks swim in circles. Research by B.K. Yamamoto indicates the brain's substantia nigra can cause animals to move in circles, and circular movement in sick animals is common.

The survival value of circular direction of movement in humans has not been extensively studied. Nobody is clear on why such movements are circular, and not some other geometric pattern. It has been speculated that people circle when confronted with unfamiliar surroundings so as to confine their aimless wonderings within a relatively small core area, perhaps increasing the likelihood of eventually finding their way by stumbling across a familiar landmark.

Historically, it was believed that circular walking by lost individuals stemmed from unequal leg length, but that possibility has been disproved because many people under such circumstances alternate the directions in which they circle. Scientists have concluded that circular walking stems from brain circuitry.

Robert Alison has a PhD in zoology and is based in Victoria, B.C.

Republished from the Winnipeg Free Press print edition September 27, 2009 A10