CRT信号显示的刺激率和信号率对警觉作业的影响

本实验系统地考察了在不同刺激率、信号率条件下警觉水平的变化 ,并分析了以往警觉理论的适应条件。实验一采用 5次 /分、1 5次 /分和 30次 /分的刺激率条件 ,发现检测正确率在各条件下随时间的变化是由于 d′下降所致 ,而β值基本不变 ,可以认为警觉随时间下降是由于疲劳所致 ;中等刺激率条件下的 d′最高 ,低刺激率次之 ,高刺激率最差并且高刺激率导致被试唤醒水平降低。实验二在 30次 /分的高刺激率条件下变化信号率 (分别为 3次 /分、6次 /分和 1 2次 /分 ) ,发现信号率变化不会改变 d′,但导致β值的变化 ,可以认为高信噪比导致被试的唤醒水平升高

The Effects of Event Rate and Signal Rate on Vigilance Performance in CRT Displays

The cause of vigilance decrement could be sensitivity loss or criterion shift.Sensitivity loss might be caused by subjects' fatigue and criterion shift resulted from change of subjects' arousal level or expectancy level. In this study, two experiments were conducted to examine effects of event rate and signal rate on observed responses and detection decision responses. 60 subjects were undergraduates or graduates. In the first experiment, three event rates were 5 event/min,15 event/min and 30 event/min. Observed responses were obtained by requiring subjects to press the space bar as soon as the signal appears on the screen.Conventional vigilance measures, as well as those derived from the signal detection theory were also used. The results indicated that, in both observed responses and detection decision responses, the medium event rate had the highest performance level and the high event rate had the lowest performance level. There was the highest criterion on the high event rate.The performances were significantly reduced in three event rate but criterion had no significant shift during the 80 minutes experiment. Therefore the performance reduces during experiment time because Ss' fatigue increase while performance loses and criterion shift on the high event rate when Ss' arousal level decline. In experiment two,one event rate,the high event rate of 30 event/min used in experiment one,and three signal rates( 3 signal/min, 6 signal/min and 12 signal/min) were used.Results showed significant differences in observed responses among signal rates but no signal rate effect was found on sensitivity.It seems that significantly low criterion is related to high signal rate and high signal/noise ratio will increase Ss' arousal level