Solomon Joshua A, Morgan Michael J, Chubb Charles F
School of Health & Medical Sciences, City St George's, University of London, UK.
University of California, Irvine, California, United States.
Perception. 2025 Aug;54(8):637-643. doi: 10.1177/03010066251340285. Epub 2025 May 30.
Search asymmetry has been called a "litmus test" for basic visual features. The letter Q is thought to contain a basic feature because () it can be found quickly, no matter how many O's it is hiding amongst and () it is much harder to find an O amongst Q's. We tested the possibility that a basic visual feature is created when two perpendicular Gabor patterns are superimposed to form a "plaid." We found relatively large effects of set size on reaction time whenever participants tried to find a Gabor hiding among plaids. Set-size effects were smaller when participants tried to find a 2- or 4-cycle-per-degree plaid that was hiding among its component Gabors. The implication is that these plaids contain a basic visual feature, which is not present in its component Gabors. This feature may be an intrinsic two-dimensionality that is extracted from the visual intensity map. Mixed-frequency plaids did not pop out from their component Gabors. This last result suggests that the visual system separates intrinsically two-dimensional image regions (e.g., corners and junctions) from intrinsically one-dimensional image regions (e.g., straight edges) after the scene is segregated into parallel spatial frequency channels.
搜索不对称性被称为基本视觉特征的“石蕊试纸测试”。字母Q被认为包含一种基本特征，因为（1）无论它藏在多少个字母O中间，都能很快被找到；（2）而要在字母Q中间找到一个字母O则要难得多。我们测试了一种可能性，即当两个垂直的伽柏图案叠加形成一个“格子图案”时，会产生一种基本视觉特征。我们发现，每当参与者试图在格子图案中找到一个隐藏的伽柏图案时，刺激集大小对反应时间有相对较大的影响。当参与者试图在其组成伽柏图案中找到一个每度2或4个周期的格子图案时，刺激集大小的影响较小。这意味着这些格子图案包含一种基本视觉特征，而这种特征在其组成伽柏图案中并不存在。这种特征可能是从视觉强度图中提取的一种内在二维性。混合频率的格子图案不会从其组成伽柏图案中突显出来。最后这个结果表明，在场景被分离为平行的空间频率通道后，视觉系统会将内在二维图像区域（如角和交叉点）与内在一维图像区域（如直线边缘）区分开来。
