Perspectives on human performance modelling

An overview of, and perspective on, human performance modelling is presented. The role of human performance models in the design process for complex man-machine systems is discussed. Then psychologically-based models and a control-theoretic approach to modelling are reviewed. Finally, a recently developed model that illustrates how features of the two approaches may be synthesized to analyze a wider range of supervisory control problems is described and discussed.     

Muscle fiber composition and blood ammonia levels after intense exercise in humans

The relationship between fiber type composition and the increase in blood ammonia was examined following a maximal O2 consumption (VO2max) test. Muscle biopsies were taken from the middle portion of the vastus lateralis for determination of fiber type percentages. Two subject groups were selected on the basis of a high (HST) or low (LST) percentage of slow-twitch fibers and compared for blood ammonia and lactate levels after exercise at work loads of approximately 85 and 110% of VO2max. An inverse relationship was found between the percentage of slow-twitch fibers and the increase in blood ammonia. Blood ammonia increased after exercise at both 85 and 110% of VO2max. However, the increase was twofold greater for the LST group following the 110% work effort. The increases in blood ammonia and lactate were positively correlated for both groups following exercise. The results suggest that the proportion of slow-twitch fibers plays an important role in determining the magnitude of the increase in blood ammonia after intense exercise.     

Effects of cuing on recall from categorized word lists.

Explored the retrieval-deficit hypothesis by comparing free-recall under cued and noncued conditions in 2 groups of 36 5- and 8-yr-olds. On a 16-word list containing either 2, 4, or 8 categories, Ss received 2 trials of noncued recall. The 2nd trial was immediately followed by a test for cued recall. A comparison between cued recall performance and noncued recall performance on Trial 2 indicates that the younger children benefited more than the older children from the cuing procedure. For both age groups, there were effects of cuing on both the number of categories recalled and the number of items per category recalled. Clustering was observed at both age-levels but appeared unrelated to recall performance. Some of the results are discussed in connection with a retrieval deficit hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)