Most people will expose the soles of their shoes only when they feel they are in a protected position and are comfortable. Watch what job candidates do with their feet. They are displaying a sense of self-assurance and control if they're sitting back, one leg crossed over the other. The moment discussions turn serious and the people are challenged with tough questions, they may suddenly uncross their legs, lean forward and place both feet firmly on the ground. This indicates they are nervous and uncomfortable about giving you an honest answer to your question.
Excerpted from Attracting & Rewarding Outstanding Employees