Department of Neurophysics, Philipps-University Marburg, , Marburg, Germany.
Philos Trans R Soc Lond B Biol Sci. 2013 Sep 9;368(1628):20130067. doi: 10.1098/rstb.2013.0067. Print 2013 Oct 19.
For natural scenes, attention is frequently quantified either by performance during rapid presentation or by gaze allocation during prolonged viewing. Both paradigms operate on different time scales, and tap into covert and overt attention, respectively. To compare these, we ask some observers to detect targets (animals/vehicles) in rapid sequences, and others to freely view the same target images for 3 s, while their gaze is tracked. In some stimuli, the target's contrast is modified (increased/decreased) and its background modified either in the same or in the opposite way. We find that increasing target contrast relative to the background increases fixations and detection alike, whereas decreasing target contrast and simultaneously increasing background contrast has little effect. Contrast increase for the whole image (target + background) improves detection, decrease worsens detection, whereas fixation probability remains unaffected by whole-image modifications. Object-unrelated local increase or decrease of contrast attracts gaze, but less than actual objects, supporting a precedence of objects over low-level features. Detection and fixation probability are correlated: the more likely a target is detected in one paradigm, the more likely it is fixated in the other. Hence, the link between overt and covert attention, which has been established in simple stimuli, transfers to more naturalistic scenarios.
对于自然场景，注意力通常通过快速呈现期间的表现或长时间观看期间的注视分配来量化。这两种范式分别在不同的时间尺度上运行，分别涉及隐蔽和显式注意。为了进行比较，我们要求一些观察者快速序列地检测目标（动物/车辆），而其他观察者则在注视被跟踪的同时自由观看相同的目标图像 3 秒。在一些刺激中，目标的对比度（增加/减少）及其背景以相同或相反的方式进行修改。我们发现，相对于背景增加目标对比度会增加注视和检测，而降低目标对比度并同时增加背景对比度几乎没有效果。整个图像（目标+背景）的对比度增加会提高检测，降低会降低检测，而注视概率不受整个图像修改的影响。与物体无关的局部对比度增加或减少会吸引注视，但不如实际物体吸引，这支持了物体优先于低水平特征的观点。检测和注视概率是相关的：在一种范式中目标越有可能被检测到，在另一种范式中它越有可能被注视。因此，在简单刺激中建立的显式和隐式注意之间的联系已转移到更自然的场景。
