Deubel Heiner, Koch Carmen, Bridgeman Bruce
Department of Psychology, Ludwig-Maximilians-Universität, München, Germany.
Vision Res. 2010 Jan;50(2):249-59. doi: 10.1016/j.visres.2009.09.020. Epub 2009 Oct 13.
It has been demonstrated that visual objects that are present after saccadic eye movements act as landmarks for the localization of stimuli across saccades, facilitating space constancy (Deubel, 2004). We here study the temporal conditions under which landmark effects occur after saccadic eye movements, and during fixation. Two small objects were presented 6 degrees in the periphery, one above the other. Observers saccaded to the space between them. One of the objects disappeared during the saccade and reappeared with a variable delay during or after the saccade. At the same time either that object or the continuously present one jumped by 1 degrees . The observer's task was to decide which object had moved. The results revealed a strong bias to assign movement to the object that was blanked, regardless of which actually moved. If both objects were blanked, the one that was blanked for a shorter time tended to be seen as stable. The effects were stronger as the onset asynchrony between the stimuli increased. Surprisingly, analogous though weaker effects occurred during visual fixation, suggesting that similar visual mechanisms relying on visual landmarks operate both across saccades and during fixation.
研究表明，扫视眼动后出现的视觉对象可作为跨扫视定位刺激的地标，促进空间恒常性（Deubel，2004）。我们在此研究扫视眼动后以及注视期间地标效应出现的时间条件。在周边6度处呈现两个小物体，一个在另一个上方。观察者扫视到它们之间的空间。其中一个物体在扫视过程中消失，并在扫视期间或之后以可变延迟重新出现。与此同时，那个物体或一直存在的物体之一跳动1度。观察者的任务是判断哪个物体移动了。结果显示，无论实际上哪个物体移动，都存在一种强烈的偏向，即倾向于将移动归因于被遮挡的物体。如果两个物体都被遮挡，被遮挡时间较短的那个物体往往被视为静止的。随着刺激之间的起始异步增加，这些效应更强。令人惊讶的是，在视觉注视期间也出现了类似但较弱的效应，这表明依赖视觉地标的类似视觉机制在扫视和注视过程中都起作用。
