On the cost and benefit of cost and benefit.

Cost-benefit analysis of reaction times has become a popular chronometric tool in the study of cognitive processes. We review the technique, assumptions underlying its application, and pitfalls that are encountered in actually implementing it in various experimental contexts, this review suggests that the unthoughtful application of the technique may cause one to draw improper conclusions about the underlying mechanisms that produce costs and benefits. The keys to the mind are few in number. Because of this, the small number of paradigms available to experimental cognitive psychology are exploited ubiquitously to reveal characteristics of a variety of mental activities. When a new technique is invented, it is eagerly coopted by large numbers of investigators who hope to unravel yet more of the mysteries of cognitive life. This is as it should be, given the limited repertoire of methodological resources. However, care must be taken to ensure that new empirical tools are examined critically and that their flaws are laid bare before they are put to use. Often this is not feasible until a technique has been used for some time, thereby permitting sufficient examples of its product to be scrutinized. Also, some period of fairly extensive application of an experimental procedure is required before investigators begin to amass occasionally discomforting feelings about its use. These feelings typically arise during day-to-day activities in the laboratory when otherwise mundane decisions about the details of an experimental design lead one to question some basic assumptions about the empirical technique that is being applied. We have had such feelings of uncertainty. The paradigm that produces our symptoms is