The purpose of this volume is to seek out, describe, and explain the shared commonalities of stress, fatigue, and workload. To understand and predict human performance response, we have to reach beyond the sterile, information-processing models to incorporate the emotive, affective, or more generally, energetic aspects of cognition. These facets of behavior surface most readily when the individual acts under stress, is faced by significant cognitive workload, or is in the grip of fatigue. However, energetic characteristics are pervasive and exert a vital and ubiquitous influence, even when...