Over E A B, Hooge I T C, Vlaskamp B N S, Erkelens C J
Physics of Man, Helmholtz Institute, Utrecht University, The Netherlands.
Vision Res. 2007 Aug;47(17):2272-80. doi: 10.1016/j.visres.2007.05.002. Epub 2007 Jul 6.
Oculomotor behavior contributes importantly to visual search. Saccadic eye movements can direct the fovea to potentially interesting parts of the visual field. Ensuing stable fixations enables the visual system to analyze those parts. The visual system may use fixation duration and saccadic amplitude as optimizers for visual search performance. Here we investigate whether the time courses of fixation duration and saccade amplitude depend on the subject's knowledge of the search stimulus, in particular target conspicuity. We analyzed 65,000 saccades and fixations in a search experiment for (possibly camouflaged) military vehicles of unknown type and size. Mean saccade amplitude decreased and mean fixation duration increased gradually as a function of the ordinal saccade and fixation number. In addition we analyzed 162,000 saccades and fixations recorded during a search experiment in which the location of the target was the only unknown. Whether target conspicuity was constant or varied appeared to have minor influence on the time courses of fixation duration and saccade amplitude. We hypothesize an intrinsic coarse-to-fine strategy for visual search that is even used when such a strategy is not optimal.
眼球运动行为对视觉搜索起着重要作用。扫视眼动可将中央凹导向视野中潜在有趣的部分。随后的稳定注视能使视觉系统分析这些部分。视觉系统可能将注视持续时间和扫视幅度用作视觉搜索性能的优化指标。在此，我们研究注视持续时间和扫视幅度的时间进程是否取决于受试者对搜索刺激的了解，特别是目标的醒目程度。我们分析了在搜索未知类型和尺寸的（可能伪装的）军车的实验中的65000次扫视和注视。平均扫视幅度随着顺序扫视和注视次数的增加而逐渐减小，平均注视持续时间则逐渐增加。此外，我们还分析了在一个搜索实验中记录的162000次扫视和注视，该实验中目标的位置是唯一未知的因素。目标醒目程度是恒定还是变化似乎对注视持续时间和扫视幅度的时间进程影响较小。我们推测视觉搜索存在一种内在的从粗到细的策略，即使在该策略并非最优时也会被使用。
