Andersen Søren K, Hillyard Steven A, Müller Matthias M
Institut für Psychologie I, Universität Leipzig, Seeburgstrasse 14-20, 04103 Leipzig, Germany.
Curr Biol. 2008 Jul 8;18(13):1006-9. doi: 10.1016/j.cub.2008.06.030.
Successfully locating a dangerous or desirable object within a cluttered visual scene is a commonplace yet highly adaptive skill. In the laboratory, this ability is modeled by visual search experiments in which subjects try to find a target item surrounded by an array of distracting stimuli. Under certain conditions, targets that are distinguishable from distractors by virtue of having a particular combination of shared sensory features (e.g., a particular color and orientation) can be found rapidly regardless of the number of distractors. To explain this highly efficient localization of feature-conjunction targets, "guided search" theories propose that attention is directed in parallel to the individual features that define the target, which then stands out from the distractors because of additive facilitation of its feature signals. Here we recorded frequency-tagged potentials evoked in human visual cortex and found that color and orientation features of target stimuli are indeed facilitated by attention in a parallel and additive manner. This additive feature-enhancement mechanism, reported here for the first time, not only enables rapid guided search but also plays a broader role in directing and sustaining attention to multi-feature objects and keeping them perceptually distinct from background clutter.
在杂乱的视觉场景中成功定位危险或目标物体是一项常见但适应性很强的技能。在实验室中，这种能力通过视觉搜索实验来模拟，在实验中，受试者试图在一系列干扰刺激中找到目标物体。在某些条件下，凭借具有特定共享感官特征组合（例如特定颜色和方向）而与干扰物区分开来的目标，无论干扰物数量多少都能被快速找到。为了解释特征联结目标的这种高效定位，“引导搜索”理论提出，注意力会并行指向定义目标的各个特征，然后由于其特征信号的累加促进作用，目标会从干扰物中脱颖而出。我们在此记录了人类视觉皮层中诱发的频率标记电位，发现目标刺激的颜色和方向特征确实以并行和累加的方式受到注意力的促进。这种首次在此报道的累加特征增强机制，不仅能实现快速引导搜索，还在引导和维持对多特征物体的注意力以及使它们在感知上与背景杂波区分开来方面发挥更广泛的作用。
