Sense mode and coupling in a vigilance task

Usarmymedical Research Laboratory, Fort Knox, Kentucky This investigation examined the performance of 36 Ss on three 90-min vigilance tasks. As time on task increased, there was a significant decrease in number of detections and false responses and a corresponding significant increase in response latency. The consistent rank order relationship between stimulus conditions suggests that there were uniform trends among these conventional response measures. There was a significant decline in sensitivity (d′) lor the closely coupled tasks, regardless of the sense mode involved. However, d′ remained fairly stable for the loosely coupled visual task. The significant increase in criterion values(β) suggest that Ss adopt a more conservative mode of responding with increasing time on task. Further, these data indicate that a lack of control of coupling effects, rather than sense mode specificity, may have confounded the interpretation of prior research on visualand auditory tasks.