Abernethy, Bruce and Masters, Rich S. W. (2011). Attention focus in sports. In Lyle J. Micheli (Ed.), Encyclopedia of sports medicine (pp. 125-127) Thousand Oaks, CA, United States: Sage. doi:10.4135/9781412961165.n52
Attention refers to the way in which a person allocates his or her mental processing capacity to the task or tasks at hand. The capacity to do mental processing is not unlimited, so effective allocation of attention is pivotal to successful learning and performance. This is especially true in the sports domain, where poor performance is often attributed to errors of attention. A missed free throw in basketball can be caused by distractions from crowd noise; a defensive player in football can be deceived by an opponent to attend to the wrong cues; or the concentration of a tennis player can waver on an easy smash. These are common occurrences in sport that illustrate the connection between control of attention and successful performance. For different types of sports, and tasks within sports, optimal performance depends on the athlete's ability to either focus attention (so as to apply the maximum mental processing resources to a single element of a task) or divide attention (so as to distribute processing resources concurrently between two or more tasks or elements of a task).