Response Classification Images in Vernier Acuity
Response Classification Images in Vernier Acuity
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Vernier Acuity 中的响应分类图像
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
S. Ellis
中科院分区：
文献类型：
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作者：
A. Ahumada;B. Beard;S. Ellis
方位选择性和局部标志机制被认为是游标敏感度判断的基础。对于两个选择任务，通过将外部噪声添加到图像，然后分别对四种类型的刺激/反应试验的噪声进行平均，可以确定有助于辨别的线性图像特征。将该方法应用于具有不同空间间隔的游标锐度任务，比较了两种理论的预测结果。三名训练有素的观察者被展示了大约5000次游标刺激试验，该刺激由两条暗水平线(5分钟乘0.3分钟)组成，内含相加的低对比度白噪声。测试了两种空间分离方式，一种是邻接，另一种是水平间隔10分钟。任务是确定目标线是对齐的还是垂直偏移的。分别对四种刺激/反应试验类型的噪声进行平均(例如，刺激=偏移，反应=对齐)。然后，将这两个未对齐的图像的和从对齐的图像的和中减去，以获得整体图像。空间平滑图像根据平滑图像中的预期变异性被量化，以允许估计图像特征的统计显著性。10min分离条件下的响应图像符合局部符号理论，出现了两个符号相反的测量垂直位置的线性算子。来自相邻刺激的图像具有与靠近的两个操作符相同的外观。方向滤波模型预测的图像相似，但在邻接区域具有最大的权重，而响应图像在那里下降到不重要。反应相关图像法，以前演示过的字母识别，澄清了游标敏锐度所使用的特征。
Orientation selective and local sign mechanisms have been proposed as the basis for vernier acuity judgments. Linear image features contributing to discrimination can be determined for a two choice task by adding external noise to the images and then averaging the noises separately for the four types of stimulus/response trials. This method is applied to a vernier acuity task with different spatial separations to compare the predictions of the two theories. Three well-practiced observers were presented around 5000 trials of a vernier stimulus consisting of two dark horizontal lines (5 min by 0.3 min) within additive low-contrast white noise. Two spatial separations were tested, abutting and a 10 min horizontal separation. The task was to determine whether the target lines were aligned or vertically offset. The noises were averaged separately for the four stimulus/response trial types (e.g., stimulus = offset, response = aligned). The sum of the two 'not aligned' images was then subtracted from the sum of the 'aligned' images to obtain an overall image. Spatially smoothed images were quantized according to expected variability in the smoothed images to allow estimation of the statistical significance of image features. The response images from the 10 min separation condition are consistent with the local sign theory, having the appearance of two linear operators measuring vertical position with opposite sign. The images from the abutting stimulus have the same appearance with the two operators closer together. The image predicted by an oriented filter model is similar, but has its greatest weight in the abutting region, while the response images fall to nonsignificance there. The response correlation image method, previously demonstrated for letter discrimination, clarifies the features used in vernier acuity.