脑检测设计分析和总结.pdf

Method Equipment： 1. IBM-兼容的个人电脑17寸VGA显示器. 2. The monitor was calibrated for gamma correction so that the luminance on the screen is a linear function of the pixel value in the image file. After gamma correction, the pixel value 0 to 255 linearly code the screen luminance from 0 to 2 40 cd/m , thus, the resolution of the luminance control was about 40/256 = 0.16 2 cd/m . Stimuli： In this study, a display contained sinusoidal patches arranged in a circle, and a simple feature, the orientation of sinusoidal gratings, was tested. This will presumably make the task more focused on an early visual sensory representation and thereby minimize the involvement of the higher-level symbolic and phonological processing. With the properties stated in the figure caption, eight spatial configurations of the grating patches were constructed (include the display illustrated in Figure 2.1). The displays were viewed binocularly at a distance of 57 cm, where the visual angle o between the center of each patch and the fixation point was 6.5 , the diameter of each o patch was 2.5 and the spatial frequency of the gratings was 1c/deg. In this study, the e entricity of 6.5o was a compromise of presenting items of large visual angle and to the fovea as close as possible. 测试流程 第一阶段：键盘训练（３分钟）：让被试适应用键盘作反应并达到一定的熟练程度。训练流程 如下： 1. 被试坐在安静的黑屋里（被试的前上方房角处可放置一个小灯泡照明），头部放在头托架 上，眼睛注视背景图的屏幕中心来适应这个亮度。指示语“请坐好，头部放在托架上，两 眼盯在屏幕中心注视点两分钟适应一下。同时调整呼吸，静下心来！”。两分钟后显示“按 回车键（ENTER ）继续”。 2. 立即显示操作指南屏幕。“每一次测试，你都将看到８个带条纹的圆盘，条纹有四种不同 的方向［横，右，竖，左］。屏幕中心有一个指针指向其中一个条纹圆盘。按回车键（ENTER） 观看一个图例” 3. 回车后呈现一个指针和信号组合图形如下图。屏幕上显示指示语：“你的任务是按键盘来 表示指针指向圆盘的条纹方向。四个键[C，D，S，A]分别代表[横，右，竖，左]四个方向。 你在键盘上从“Ｘ”键到这四个键的指向，正好就是这四个条纹的方向。容易记住吧？按 回车键（ENTER）继续。” 4. 两秒钟后，听见一个小的“嘀”声，同时呈现一个指针和信号