In 2009, a German scientist named Jan Souman took a group of subjects out to empty parking lots and open fields, blindfolded them, and instructed them to walk in a straight line. Some of them managed to keep to a straight course for ten or twenty paces; a few lasted for 50 or a hundred. But in the end, all of them wound up circling back toward their points of origin. Not many of them. Not most of them. Every last one.

"And they have no idea," Dr. Souman told NPR. "They were thinking that they were walking in a straight line all the time." Dr. Souman's research team explored every imaginable explanation. Some people turned to the right while others turned to the left, but the researchers could find no discernable pattern. As a group, neither left-handed nor right-handed subjects demonstrated any predisposition for turning one way more than the other; nor did subjects tested for either right- or left-brain dominance. The team even tried gluing a rubber soul to the bottom of one shoe to make one leg longer than the other.

"It didn't make any difference at all," explained Dr. Souman. "So again, that is pretty random what people do." In fact, it isn't even limited to walking. Ask people to swim blindfolded or drive a car blindfolded and, no matter how determined they may be to go straight, they quickly begin to describe peculiar looping circles in one direction or the other.