Rajashekar Umesh, Bovik Alan C, Cormack Lawrence K
Department of Electrical and Computer Engineering and Center for Perceptual Systems, The University of Texas at Austin, Austin, TX 78712, USA.
J Vis. 2006 Mar 13;6(4):379-86. doi: 10.1167/6.4.7.
Visual search experiments have usually involved the detection of a salient target in the presence of distracters against a blank background. In such high signal-to-noise scenarios, observers have been shown to use visual cues such as color, size, and shape of the target to program their saccades during visual search. The degree to which these features affect search performance is usually measured using reaction times and detection accuracy. We asked whether human observers are able to use target features to succeed in visual search tasks in stimuli with very low signal-to-noise ratios. Using the classification image analysis technique, we investigated whether observers used structural cues to direct their fixations as they searched for simple geometric targets embedded at very low signal-to-noise ratios in noise stimuli that had the spectral characteristics of natural images. By analyzing properties of the noise stimulus at observers' fixations, we were able to reveal idiosyncratic, target-dependent features used by observers in our visual search task. We demonstrate that even in very noisy displays, observers do not search randomly, but in many cases they deploy their fixations to regions in the stimulus that resemble some aspect of the target in their local image features.
视觉搜索实验通常涉及在空白背景下的干扰物中检测显著目标。在这种高信噪比的场景中，研究表明观察者在视觉搜索过程中会利用目标的颜色、大小和形状等视觉线索来规划他们的眼跳。这些特征对搜索性能的影响程度通常通过反应时间和检测准确性来衡量。我们研究了人类观察者在信噪极低的刺激中是否能够利用目标特征成功完成视觉搜索任务。使用分类图像分析技术，我们调查了观察者在搜索嵌入具有自然图像光谱特征的噪声刺激中、信噪极低的简单几何目标时，是否使用结构线索来引导他们的注视。通过分析观察者注视点处噪声刺激的特性，我们能够揭示观察者在视觉搜索任务中使用的独特的、依赖于目标的特征。我们证明，即使在非常嘈杂的显示中，观察者也不是随机搜索，而是在许多情况下将他们的注视点部署到刺激中在局部图像特征上类似于目标某些方面的区域。
