Warren R C, Darwin C J
Department of Medical Physics and Bioengineering, University College and Middlesex School of Medicine, London.
Br J Radiol. 1989 Sep;62(741):817-23. doi: 10.1259/0007-1285-62-741-817.
The ability of an observer to detect variations in size of a geometrical image feature have been investigated using receiver operating characteristic (ROC) analysis. Three types of image were constructed using computer graphics: disc-shaped targets of variable radius, model chest radiographs showing a variable heart diameter and model arterial angiograms with variable vessel width. Five factors were investigated: observer experience, variation of detectability with theoretical signal-to-noise ratio, the prior probability of the presence of an abnormality, viewing distance, and uncertainty in the location of an abnormality. In all but one experiment, excellent agreement was found between measured detectabilities and the predictions of signal detection theory, providing an initial practice session was included for each observer. No significant variation in detectability was found using six different prior probabilities and two different viewing distances, and the reduction in detectability for a four-alternative location task was in good agreement with theoretical predictions. The high statistical efficiencies found for the detection of geometrical signals suggest that the levels of observer "internal" noise arising from decision-making processes during an ROC experiment are very low.
已使用接受者操作特征（ROC）分析研究了观察者检测几何图像特征大小变化的能力。使用计算机图形构建了三种类型的图像：半径可变的圆盘形目标、显示心脏直径可变的胸部X光片模型以及血管宽度可变的动脉血管造影模型。研究了五个因素：观察者经验、可检测性随理论信噪比的变化、异常存在的先验概率、观察距离以及异常位置的不确定性。除一项实验外，在所有实验中，发现测量的可检测性与信号检测理论的预测之间具有极好的一致性，前提是为每个观察者都安排了初始练习环节。使用六种不同的先验概率和两种不同的观察距离时，未发现可检测性有显著变化，并且四项选择位置任务中可检测性的降低与理论预测高度吻合。在检测几何信号时发现的高统计效率表明，在ROC实验中，由决策过程产生的观察者“内部”噪声水平非常低。
