I'm amazed when I hear archers debating the pros and cons of shooting with either one or both eyes open. Physiologically speaking, monocular vision (closing one eye) diminishes both peripheral field of view and depth perception. In essence, you're half-blind when you aim with one eye. With a complete field of view, you can acquire your target considerably quicker than you can with one eye closed. If an animal is moving left or right in your periphery and you close one eye, you'll lose it.