I have always had a tendency to look down, which has caused others to make interesting psychological claims ranging from a lack of confidence or excessive diffidence to snobbishness, and all manner of things in between. There are times when I look down to make sure I place my feet surely, and there are times when I look down because to look someone squarely in the face would mean smelling their breath, but mostly, I look down because I like the rhythm of movement.
On a trail, I will look down to see what type of creatures I may expect to meet up with. That may sound like I am some sort of tracker, but really, all I am looking for is whether I will meet humans, dogs, or wild animals. If all I see are very large paw prints, I will probably turn around. If I see dog prints without humans, I will be a bit more wary.