Wagatsuma Nobuhiko, Shimizu Ryohei, Sakai Ko
Laboratory for Computational Vision Science, Department of Computer Science, University of Tsukuba, Japan.
J Vis. 2008 Aug 5;8(7):22.1-19. doi: 10.1167/8.7.22.
Spatial attention alters contrast gain in early visual areas, which might affect the determination of border ownership (BO) that indicates the direction of figure with respect to the border. We investigated the role of spatial attention applied to early vision in the determination of BO with a computational model that consists of V1, V2, and posterior parietal (PP) modules. Attention alters contrast gain in the V1 module so that it enhances local contrast. The V2 module determines BO based on the surrounding contrast extracted by the V1 module. The simulation results showed that the attention significantly modulates BO; BO is even flipped in figures with ambiguous BO while BO is stable for unambiguous figures such as a simple square. To evaluate the model quantitatively, we carried out psychophysical experiments to measure the effects of attention in the perception of BO and compared the results with those from corresponding simulations. The model showed good agreement with human perception including the determination of BO for ambiguous random-block stimuli. These results indicate that the activity of BO-selective neurons could be modulated significantly by spatial attention that alters local contrast gain in V1, which may account in part for automatic, bi-stable perception in ambiguous figures.
空间注意力会改变早期视觉区域的对比度增益，这可能会影响边界所有权（BO）的判定，BO指示图形相对于边界的方向。我们使用一个由V1、V2和后顶叶（PP）模块组成的计算模型，研究了应用于早期视觉的空间注意力在BO判定中的作用。注意力会改变V1模块中的对比度增益，从而增强局部对比度。V2模块根据V1模块提取的周围对比度来确定BO。模拟结果表明，注意力显著调节BO；在BO模糊的图形中，BO甚至会翻转，而对于明确的图形（如简单正方形），BO则是稳定的。为了定量评估该模型，我们进行了心理物理学实验，以测量注意力对BO感知的影响，并将结果与相应模拟结果进行比较。该模型与人类感知表现出良好的一致性，包括对模糊随机块刺激的BO判定。这些结果表明，BO选择性神经元的活动可能会受到空间注意力的显著调节，空间注意力会改变V1中的局部对比度增益，这可能部分解释了模糊图形中自动的、双稳态的感知。
