A basic principle of ancient Chinese Feng Shui is that you should not sit with your back to a space. In other words, you need to have your back against a wall, not your face facing a wall. I believe there is a reason for this. When there is a space behind you, human instinct forces you to pay a subconscious attention on that space (we are very alert to danger from behind), making it harder to concentrate on what is in front of you.