Institute of Cognitive Science, University of Osnabrück, Osnabrück, Germany.
Social and Media Psychology, Department of Psychology, University of Cologne, Köln, Germany.
Sci Rep. 2017 May 23;7(1):2311. doi: 10.1038/s41598-017-02526-1.
Many eye-tracking studies investigate visual behavior with a focus on image features and the semantic content of a scene. A wealth of results on these aspects is available, and our understanding of the decision process where to look has reached a mature stage. However, the temporal aspect, whether to stay and further scrutinize a region (exploitation) or to move on and explore image regions that were yet not in the focus of attention (exploration) is less well understood. Here, we investigate the trade-off between these two processes across stimuli with varying properties and sizes. In a free viewing task, we examined gaze parameters in humans, involving the central tendency, entropy, saccadic amplitudes, number of fixations and duration of fixations. The results revealed that the central tendency and entropy scaled with stimulus size. The mean saccadic amplitudes showed a linear increase that originated from an interaction between the distribution of saccades and the spatial bias. Further, larger images led to spatially more extensive sampling as indicated by a higher number of fixations at the expense of reduced fixation durations. These results demonstrate a profound shift from exploitation to exploration as an adaptation of main gaze parameters with increasing image size.
许多眼动追踪研究都集中在图像特征和场景的语义内容上，以研究视觉行为。在这些方面已经有了大量的研究成果，我们对注视点决策过程的理解已经达到了成熟阶段。然而，对于时间方面，即是停留并进一步仔细观察一个区域（开发）还是继续前进并探索尚未成为关注焦点的图像区域（探索），我们的理解还不够充分。在这里，我们研究了在具有不同特性和大小的刺激之间这两个过程之间的权衡。在自由观看任务中，我们检查了人类的注视参数，包括中央趋势、熵、扫视幅度、注视次数和注视持续时间。结果表明，中央趋势和熵与刺激大小成正比。平均扫视幅度呈线性增加，这源于扫视分布与空间偏向之间的相互作用。此外，更大的图像导致空间上更广泛的采样，表现为注视次数增加，而注视持续时间减少。这些结果表明，随着图像尺寸的增加，主要注视参数发生了深刻的转变，从开发转向探索。
