Recent findings in stress research indicate the necessity for examining the distribution of the operator's attention in complex tasks as well as his information transmission capabilities. This study examines the effects of alcohol and noise on a complex tracking and signal-detection task with particular reference to changes in selective attention. The operator was instructed to give the tracking task priority. In noise tracking performance improved, but detection of lights placed on the periphery of vision was degraded. Alcohol had the same effect on peripheral detection, but tracking performance fell. It was concluded that the effect of alcohol on such simulated driving skills embodied two factors: the first an increase in attentional bias towards the high priority regions of the visual field, and the second a decrease in the information transmission rate. Since from the point of view of the tracking task these factors are mutually eLltagonistic, there may be an offsetting of the loss in transmission rate by more optimal dispositions of attention. The loss of peripheral awareness in this event is inevitable, and even at the low alcohol levels used was of apparently serious proportions. I 1 P S Y 61

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Driver behavior in the vehicle-following situation, a major source of road accidents, was investigated using a controlled-track experiment. Drivers were found to adopt headways of approximately 2 s irrespective of speed of travel, driving experience, or instructed probability of the leading vehicle's stopping. Under the optimal conditions used, drivers demonstrated that such headways were more than adequate to avoid tail-end collisions in an emergency situation. The implications of these results for the development of perceptual-motor support devices and the attribution of causes in road accidents are discussed.

Deficits in job satisfaction and performance have been reported among operators of modern cordless telephone switchboards relative to the operation of the older cord switchboards. The attentional demands of these switchboards were investigated using, as an index of attention, the amplitude of the cortical evoked potential (CEP) to an appropriate task-relevant event. However, no reliable differences in the CEP were obtained; nor indeed were differences in alpha activity or heart rate present. Emphasis is placed upon the methodological importance of this contribution in drawing attention to the CEP as a measure of psychological processes in applied contexts.