Engmann Sonja, 't Hart Bernard M, Sieren Thomas, Onat Selim, König Peter, Einhäuser Wolfgang
University of Osnabrück, Osnabrück, Germany.
Atten Percept Psychophys. 2009 Aug;71(6):1337-52. doi: 10.3758/APP.71.6.1337.
In natural vision, shifts in spatial attention are associated with shifts of gaze. Computational models of such overt attention typically use the concept of a saliency map: Normalized maps of center-surround differences are computed for individual stimulus features and added linearly to obtain the saliency map. Although the predictions of such models correlate with fixated locations better than chance, their mechanistic assumptions are less well investigated. Here, we tested one key assumption: Do the effects of different features add linearly or according to a max-type of interaction? We measured the eye position of observers viewing natural stimuli whose luminance contrast and/or color contrast (saturation) increased gradually toward one side. We found that these feature gradients biased fixations toward regions of high contrasts. When two contrast gradients (color and luminance) were superimposed, linear summation of their individual effects predicted their combined effect. This demonstrated that the interaction of color and luminance contrast with respect to human overt attention is--irrespective of the precise model--consistent with the assumption of linearity, but not with a max-type interaction of these features.
在自然视觉中，空间注意力的转移与注视的转移相关联。这种外显注意力的计算模型通常使用显著性图的概念：针对各个刺激特征计算中心-外周差异的归一化图，并将它们线性相加以获得显著性图。尽管此类模型的预测与注视位置的相关性比随机水平更好，但其机制假设的研究较少。在这里，我们测试了一个关键假设：不同特征的效应是线性相加还是根据最大类型的相互作用相加？我们测量了观察者观看自然刺激时的眼睛位置，这些自然刺激的亮度对比度和/或颜色对比度（饱和度）朝着一侧逐渐增加。我们发现这些特征梯度将注视偏向高对比度区域。当两个对比度梯度（颜色和亮度）叠加时，它们各自效应的线性总和预测了它们的综合效应。这表明，就人类外显注意力而言，颜色和亮度对比度的相互作用——无论精确模型如何——都与线性假设一致，而与这些特征的最大类型相互作用不一致。
