Shedden J M, Nordgaard C L
Department of Psychology, PC-406, McMaster University, 1280 Main Street West, Ontario, Hamilton, Canada.
Brain Res Cogn Brain Res. 2001 Mar;11(1):59-75. doi: 10.1016/s0926-6410(00)00064-1.
Event-related potentials (ERPs) were recorded from volunteers performing a task requiring simple judgements about the spatial location of a single target that could appear with equal probability to the left or right of fixation. A robust finding in the ERP literature is a dichotomy between attentional selection for spatial and non-spatial features. Visual spatial selection is manifest as a modulation of early components (P1, N1) that reveal exogenous processes, while non-spatial selection is revealed by the presence of longer latency endogenous components (N2). We present an analysis of several conditions that require different degrees of visual analysis to confirm the location of the single target, and show that spatial selection can be manifest at early (N1) or later (N2) stages. Observers identified the location of targets that were more salient (2D line drawings with abrupt onset) or less salient (2D line drawings without abrupt onset or 3D objects embedded in random-dot stereograms). We examined differences in amplitude, latency, and topography of early ERP components (P1, N1, P2, N2), and compared responses measured over the left and right hemispheres in response to left and right targets. The results support the hypothesis that the processes involved in spatial selection can be manifest at early or late stages, dependent on the quality of the incoming data. Moreover, the iterative process by which the percept is established benefits from a change in the visual input that is specific to the target.
事件相关电位（ERPs）是从志愿者身上记录下来的，这些志愿者执行一项任务，即对单个目标的空间位置进行简单判断，该目标出现在注视点左侧或右侧的概率相等。ERP文献中的一个有力发现是空间和非空间特征的注意力选择之间存在二分法。视觉空间选择表现为早期成分（P1、N1）的调制，这些成分揭示了外源性过程，而非空间选择则由较长潜伏期的内源性成分（N2）的存在揭示。我们对几种需要不同程度视觉分析以确认单个目标位置的条件进行了分析，并表明空间选择可以在早期（N1）或晚期（N2）阶段表现出来。观察者识别更显著（具有突然 onset 的二维线条图）或不太显著（没有突然 onset 的二维线条图或嵌入随机点立体图中的三维物体）的目标位置。我们检查了早期ERP成分（P1、N1、P2、N2）的幅度、潜伏期和地形图差异，并比较了左半球和右半球对左、右目标的反应测量结果。结果支持这样的假设，即空间选择所涉及的过程可以在早期或晚期表现出来，这取决于传入数据的质量。此外，建立感知的迭代过程受益于特定于目标的视觉输入变化。
