 A further point of contrast with perceptual learning is perception-based skills, such as dart-throwing or racecar driving. To understand the relationship between perceptual learning and perception-based skills, start by considering the following case. Williams and Davids (1998) reported that when expert soccer players defend opponents, they focus longer on their opponent’s hips than non-experts do. This tuned attention is a long-term change in perception that results from practice or experience. That is, it is an instance of perceptual learning (see  section 2.3  below). Such changes certainly serve to enable perception-based skills. For instance, attending to the hips is part of what enables the soccer players to defend well. Since the hips provide a cue for what the offensive player will do next, when the defender attends there, it helps them to do all sorts of things: to keep the offensive player from dribbling by them; to keep the offensive player from completing a pass; and to keep them from shooting and scoring. Without the attentional tuning, the expert soccer players would not be able to perform as high above baseline as they do.