Kurzawski Jan W, Qiu Brenda S, Majaj Najib J, Benson Noah, Pelli Denis G, Winawer Jonathan
Department of Psychology, New York University, New York, NY, USA.
Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands.
bioRxiv. 2025 Feb 28:2024.04.03.587977. doi: 10.1101/2024.04.03.587977.
Visual recognition is limited by both object size (acuity) and spacing. The spacing limit, called "crowding", is the failure to recognize an object in the presence of other objects. Here, we take advantage of individual differences in crowding to investigate its biological basis. Crowding distance, the minimum object spacing needed for recognition, varies 2-fold among healthy adults. We test the conjecture that this variation in psychophysical crowding distance is due to variation in cortical map size. To test this, we made paired measurements of brain and behavior in 50 observers. We used psychophysics to measure crowding distance and calculate , the number of letters that fit into each observer's visual field without crowding. In the same observers, we used fMRI to measure the surface area (mm) of retinotopic maps V1, V2, V3, and V4. Across observers, is proportional to the surface area of V4 but is uncorrelated with the surface area of V1 to V3. The proportional relationship of to area of V4 indicates conservation of across individuals: letters can be recognized if they are spaced by at least 1.4 mm on the V4 map, irrespective of map size and psychophysical crowding distance. We conclude that the size of V4 predicts the spacing limit of visual perception.
视觉识别受到物体大小（敏锐度）和间距的限制。这种间距限制被称为“拥挤现象”，即当存在其他物体时无法识别某个物体。在此，我们利用拥挤现象中的个体差异来探究其生物学基础。拥挤距离是识别所需的最小物体间距，在健康成年人中其变化幅度达2倍。我们检验了这样一个推测，即心理物理学上拥挤距离的这种变化是由于皮质图谱大小的变化所致。为了验证这一点，我们对50名观察者的大脑和行为进行了配对测量。我们运用心理物理学方法来测量拥挤距离，并计算每个观察者在无拥挤情况下视野中可容纳的字母数量。在相同的观察者中，我们使用功能磁共振成像（fMRI）来测量视网膜拓扑图谱V1、V2、V3和V4的表面积（平方毫米）。在所有观察者中，与V4的表面积成正比，但与V1至V3的表面积无关。与V4面积的比例关系表明在个体间是守恒的：如果字母在V4图谱上的间距至少为1.4毫米，那么无论图谱大小和心理物理学上的拥挤距离如何，这些字母都能被识别。我们得出结论，V4的大小预示着视觉感知的间距限制。
