When perfecting patterns, you train to focus on your proprioception, your internal awareness of exactly how your body is positioned at each moment. This allows you to master the movements and use perfect form while executing techniques. However, when sparring, your focus must be external; it must encompass both the opponent and your immediate surroundings, including the ring boundaries, the location of the referee and judges, the elapsed time, and the score.
Focus also applies to adjusting the focal length of the eyes to make an image more distinct or clearer. When the eyes focus on one thing, other things within the field of vision are out of focus and not as distinct or clear, which causes the brain to concentrate upon the object that is in focus. When sparring, this may lead to fixation on one area of the opponent’s body, such as the feet, and cause the fighter not to see a hand attack or not react fast enough to a hand attack.
The eyes not only perceive colors and details, they also detect movement. The retina, located at the back of the eye, contains two types of receptors, cones and rods, which transform incoming light into the electro-chemical signals. The cones are more sensitive to color and detail, while the rods are more sensitive to light and movement. There is a higher concentration of cones near the center of the retina; therefore, there is clearer focus and more detail in the center of the field of vision. The surrounding retina consists mostly of rods that are more sensitive to movement. Fighters are more concerned with movement than they are with detail.