Automaticity is an important phenomenon in everyday mental life. Most of us recognize that we perform routine activities quickly and effortlessly, with little thought and conscious awareness in short, automatically (James, 1890). As a result, we often perform those activities on "automatic pilot" and turn our minds to other things. For example, we can drive to dinner while conversing in depth with a visiting scholar, or we can make coffee while planning dessert. However, these benefits may be offset by costs. The automatic pilot can lead us astray, causing errors and sometimes catastrophes (Reason & Myceilska, 1982). If the conversation is deep enough, we may find ourselves and the scholar arriving at the office rather than the restaurant, or we may discover that we aren't sure whether we put two or three scoops of coffee into the pot.

Automaticity is also an important phenomenon in skill acquisition (e.g., Bryan & Harter, 1899). Skills are thought to consist largely of collections of automatic processes and procedures (e.g., Chase & Simon, 1973; Logan, 1985b). For example, skilled typewriting involves automatic recognition of words, translation of words into keystrokes, and execution of keystrokes (Salthouse, 1986). Moreover, the rate of automatization is thought to place important limits on the rate of skill acquisi tion: LaBerge and Samuels (1974) claimed that beginning readers may not be able to learn to read for meaning until they have learned to identify words and letters automatically.

Over the last decade, considerable progress has been made in understanding the nature of automaticity and the conditions under which it may be acquired (for reviews, see Kahneman & Treisman, 1984; LaBerge, 1981; Logan, 1985b; Schneider, Dumais, & Shiffrin, 1984). There is evidence that automatic processing differs qualitatively from nonautomatic processing in several respects: Automatic processing is fast (Neely, 1977; Posner & Snyder, 1975), effortless (Logan, 1978, 1979; Schneider & Shiffrin, 1977), autonomous (Logan, 1980; Posner & Snyder, 1975; Shiffrin & Schneider, 1977; Zbrodoff& Logan, 1986), stereotypic (McLeod, McLaughlin, & NimmoSmith, 1985; NavehBenjamin & Jonides, 1984), and unavailable to conscious awareness (Carr, McCauley, Sperber, & Parmalee, 1982; Marcel, 1983). There is also evidence that automaticity is acquired only in consistent task environments, as when stimuli are mapped consistently onto the same responses throughout practice. Most of the properties of automaticity develop through practice in such environments (Logan, 1978, 1979; Schneider & Fisk, 1982; Schneider & Shiffrin, 1977; Shiffrin & Schneider, 1977).

Automaticity is commonly viewed as a special topic in the study of attention. The modal view links automaticity with a singlecapacity model of attention, such as Kahneman's (1973). It considers automatic processing to occur without attention (e.g., Hasher & Zacks, 1979; Logan, 1979, 1980; Posner & Snyder, 1975; Shiffrin & Schneider, 1977), and it interprets the acquisition of automaticity as the gradual withdrawal of attention (e.g., LaBerge & Samuels, 1974; Logan, 1978; Shiffrin & Schneider, 1977). The modal view has considerable power, accounting for most of tile properties of automaticity: Automatic processing is fast and effortless because it is not subject to attentional limitations. It is autonomous, obligatory, or uncontrollable because attentional control is exerted by allocating capacity; a process that does not require capacity cannot be controlled by allocating capacity. Finally, it is unavailable to consciousness because attention is the mechanism of consciousness and only those things that are attended are available to consciousness (e.g., Posner & Snyder, 1975).