Foulsham Tom, Underwood Geoffrey
School of Psychology, University of Nottingham, Nottingham, UK.
J Vis. 2008 Feb 20;8(2):6.1-17. doi: 10.1167/8.2.6.
Saliency map models account for a small but significant amount of the variance in where people fixate, but evaluating these models with natural stimuli has led to mixed results. In the present study, the eye movements of participants were recorded while they viewed color photographs of natural scenes in preparation for a memory test (encoding) and when recognizing them later. These eye movements were then compared to the predictions of a well defined saliency map model (L. Itti & C. Koch, 2000), in terms of both individual fixation locations and fixation sequences (scanpaths). The saliency model is a significantly better predictor of fixation location than random models that take into account bias toward central fixations, and this is the case at both encoding and recognition. However, similarity between scanpaths made at multiple viewings of the same stimulus suggests that repetitive scanpaths also contribute to where people look. Top-down recapitulation of scanpaths is a key prediction of scanpath theory (D. Noton & L. Stark, 1971), but it might also be explained by bottom-up guidance. The present data suggest that saliency cannot account for scanpaths and that incorporating these sequences could improve model predictions.
显著性图模型解释了人们注视位置的一小部分但显著的方差，但用自然刺激对这些模型进行评估却产生了喜忧参半的结果。在本研究中，记录了参与者在为记忆测试做准备（编码）时观看自然场景彩色照片以及随后识别这些照片时的眼动情况。然后，将这些眼动与一个定义明确的显著性图模型（L. Itti和C. Koch，2000）的预测进行比较，比较内容包括个体注视位置和注视序列（扫描路径）。显著性模型在预测注视位置方面明显优于考虑了向中央注视偏差的随机模型，在编码和识别阶段都是如此。然而，在多次观看同一刺激时所形成的扫描路径之间的相似性表明，重复性扫描路径也会影响人们的注视位置。自上而下对扫描路径的重现是扫描路径理论（D. Noton和L. Stark，1971）的一个关键预测，但它也可能由自下而上的引导来解释。目前的数据表明，显著性无法解释扫描路径，纳入这些序列可能会改善模型预测。
