Noise effects on human performance: a meta-analytic synthesis

Noise is a pervasive and influential source of stress. Whether through the acute effects of impulse noise or the chronic influence of prolonged exposure, the challenge of noise confronts many who must accomplish vital performance duties in its presence. Although noise has diffuse effects, which are shared in common with many other chronic forms of stress, it also exerts its own specific influences on various forms of cognitive and motor response. We present a quantitative evaluation of these influences so that their harmful effects can be mitigated, their beneficial effects exploited, and any residual effects incorporated and synthesized into selection, training, and design strategies to facilitate human performance capacities. Predictions of single and joint moderator effects were made on the basis of major theories of noise and performance, specifically those explanations based on arousal, masking, or cognitive-resource mechanisms. These predictions were tested through moderator analyses of effects as a function of task type, performance measure, noise type and schedule, and the intensity and duration of exposure. Observed outcome effects (797 effect sizes derived from 242 studies) varied as a function of each of these moderators. Collective findings identified continuous versus intermittent noise, noise type, and type of task as the major distinguishing characteristics that moderated response. Mixed evidence was obtained for the traditional arousal and masking explanations for noise effects. The overall pattern of findings was most consistent with the maximal adaptability theory, a mental-resource-based explanation of stress and performance variation.     

A Framework of Statistical Tests For Comparing Mean and Covariance Structure Models

Temporal patterning in blood glucose (BG) consistent with fractals—how BG follows a repetitive pattern through resolutions of time—was used to examine 2 different samples of adolescents with Type 1 diabetes (10–14 years). Sample 1 contained 10 adolescents with longtime series for accurate estimations of long-term dependencies associated with fractals. The second contained 94 adolescents measured multiple times daily over a 2-week period corresponding to psychosocial measures. In both samples, temporal dependencies in BG showed patterns consistent with fractals. In the second sample, temporal dependencies were associated with indicators of vigilant regulation including adolescents' higher anxiety, mothers' higher monitoring, and intrusive support. The existence of temporal dependencies in BG moderated the relationship between glycosylated hemoglobin (Hb_A1c) and indicators of low BG risk but not the relationship between Hb_A1c and high BG risk. These results show how a biomedical indicator may be susceptible to metric issues associated with fractals.