Control Theoretic Approaches to Age-Related Differences in Skilled Performance
Richard J. Jagacinski Ohio State University
Many tasks studied by cognitive psychologists involve a series of relatively independent stimulus patterns. Experimental participants view, listen to, or feel some stimulus pattern for a short period of time and respond by pressing one of several buttons or by writing or saying one of several limited response messages. After a short pause, another stimulus pattern is presented, and the procedure is repeated. Typically, the presentation of the next stimulus pattern is independent of the preceding response.
The tasks that are studied in control theoretic approaches to skilled performance differ from this prototypical structure in several ways (e.g., Flach, 1990). The response is extended over time, and it interacts with at least part of the stimulus pattern, which also varies over some extended time period. The response consists of a stream of behavior, and similarly the stimulus consists of a stream of patterns over time. The interactive coupling of the response stream to the stimulus stream and of the stimulus stream to the response stream creates a loop structure, which may or may not be stable (e.g., Milsum, 1966; Pew, 1974). For example, vehicular control tasks such as driving a car or piloting an aircraft involve interactive streams of stimuli and responses. One only has to lose control of a car on icy pavement or induce oscillations in a cloud enshrouded aircraft to appreciate that stability is an important property of these loop structures. Like many