Performance and Physiological Indicants of Activation in a Vigilance Situation

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Abstract
Changes in performance and in four physiological measures during the course of a 1-hr. vigil and as a function of signal presentation rate were studied. Based on data obtained from six Ss during a total of 24 vigils, performance (% correct detections) and skin conductance decreased during the course of a vigil, heart rate remained constant, and neck tension level increased. There was no consistent tendency for Ss to perform at a higher level when signals were presented at a relatively fast rate than when presented at a slower rate. However, their performance was differentially affected by presentation rate, some performing better during the fast rate, some during the slow rate, and others showing no change. A positive relationship was found between the relative performance level manifested during the two rates (fast rate expressed relative to slow) and the relative magnitudes of skin conductance, heart rate, and neck tension level. The results were interpreted as supporting the hypothesis that variations in vigilance performance are in part determined by changes in activation level. The feasibility of recording physiological information in order to ascertain more accurately which factors are contributing to variations in performance in a given vigilance situation seems to have been demonstrated.