Moderating the Performance
Effects of Stressors
Clint A. Bowers Jeanne L. Weaver Ben B. Morgan Jr. University of Central Florida
As illustrated by several of the chapters in this volume, there is an increasing pressure on human operators to perform complex tasks effectively under a variety of stressful conditions. Consequently, there is also an increasing pressure on scientists to understand the performance effects of stress, to predict the effects of novel stressors, and to intervene to reduce potential negative stress effects. Unfortunately, the literature regarding stress and human performance frequently provides little guidance for responding to these demands. Although there are literally hundreds of published manuscripts in this area, the accumulated findings are somewhat contradictory, and it is often difficult to draw unequivocal conclusions about the effects of a given stressor.
For example, one can imagine several situations in which it would be useful to understand how performance is affected by noise. A recent literature review considered 58 such investigations and found that 29 studies reported a performance decrement due to noise exposure, 22 reported no effects, and 7 reported improved performance ( Gawron, 1982). It is not difficult to understand why system designers, policy makers, and researchers might be frustrated by this mixed pattern of results.
In the case of laboratory research, this variability of results is frequently attributed to methodological problems such as errors in experimental design and the use of assessment methods with questionable validity ( Weaver, Morgan, Adkins-Holmes, & Hall, 1992). Although applied research is vulnerable to these same sources of error, field researchers must also consider additional error variance that might be introduced by the frequent inability to employ random sam