Introduction A domain expert can distinguish intricate perceptual information with remarkable ease. An experienced “birder” (bird watcher), for example, can easily discern subtle shapes and colors that differentiate a magnolia warbler from a MacGillivary warbler. Acquiring perceptual expertise in a specific domain is achieved through years of extensive practice and training. This chapter examines how perceptual expertise, based on experience “in the world” and training in the laboratory, develops. In the first section, we discuss the cognitive and neurological processes of perception that distinguish experts from their novice counterparts. We will examine experts of object recognition such as birders, canine judges, car enthusiasts, and fingerprint examiners. Next, we will discuss experts who possess domain-specific perceptual skills, such as chess players and radiologists, who specialize in the recognition of configurations and patterns of elements in visual displays. In the second section, we will explore expertise training in the laboratory and how training techniques are applied in work situations to hone the perceptual skills of transport security officers. Finally, we will suggest potential directions for research on perceptual learning and expertise. Object Expertise in Domains of Human Activity The level at which an object is first recognized as a member of a category and represented in memory is referred to as the entry point of recognition (Jolicoeur, Gluck, and Kosslyn, 1984). For novices, the entry point of recognition is the basic level (Jolicoeur, Gluck, and Kosslyn, 1984; Rosch et al., 1976). At this level, objects are recognized as “birds,” “dogs,” “cars,” and so on. Rosch et al. (1976) showed that objects at the basic level (e.g., “bird”) are more structurally similar in comparison to objects at a more general, superordinate (e.g., “animals”) level of abstraction. Objects at the more specific, subordinate level (e.g., “Nashville warbler”) tend to be more similar in shape, but the basic level categories are the most distinctive from one another at that level (e.g., “birds” versus “dogs”). Given its distinctive perceptual properties, the basic level is the level at which objects are first perceived and recognized. That is, people are faster to identify an object at the basic level (e.g., “bird,” “chair”) than they are to identify the same object at the more general, superordinate level (e.g., “animal,” “furniture”) and at the more specific, subordinate level (e.g., “warbler,” “rocking chair”) (Jolicoeur, Gluck, and Kosslyn, 1984; Rosch et al., 1976).