Valdes-Sosa M, Bobes M A, Rodriguez V, Pinilla T
Centro de Neurosciencias de Cuba, La Habana, Cuba.
J Cogn Neurosci. 1998 Jan;10(1):137-51. doi: 10.1162/089892998563743.
Although psychophysical evidence for object-based attention has been reported, corresponding studies with event-related potentials (ERPs) are scarce. Here subjects were presented with perceptual fields containing two superimposed objects (transparent surfaces generated by two sets of dots in rigid rotation around fixation, each set of a different color and direction of motion) or only one object (the same dots but either at rest or all rotating in the same direction). Brief (150-msec) rectilinear displacements affected either of the sets at random ISIs of 350 to 550 msec. Attention was directed to one set of dots, guided by color, in order to discriminate the direction of their displacement. Motion-onset ERPs elicited by these displacements were compared for attended and unattended dots. When the perceptual field consisted of two objects, strong suppression of P1 and N1 was obtained in the ERPs associated with the unattended object. No suppression was found with the field containing a single object, although an enhanced selection negativity was found in ERPs associated with attended dots (selected by color). Since the two objects occupied the same region of visual space, the suppression of P1/N1 cannot be explained by the space-based mechanisms but is consistent with object-based attentional selection at early stages of vision. The results highlight the role of perceptual organizations in enabling alternative attentional mechanisms.
尽管已有关于基于客体注意的心理物理学证据的报道，但采用事件相关电位（ERP）进行的相应研究却很稀少。在此实验中，向受试者呈现的感知区域包含两个叠加的客体（由围绕注视点做刚性旋转的两组点产生的透明表面，每组点颜色不同且运动方向各异）或仅一个客体（相同的点，但要么静止，要么都朝同一方向旋转）。短暂的（150毫秒）直线位移在350至550毫秒的随机刺激间隔时间内随机影响其中一组点。通过颜色引导，将注意力指向一组点，以辨别其位移方向。对这些位移引发的运动起始ERP进行比较，观察其在被注意点和未被注意点上的情况。当感知区域由两个客体组成时，在与未被注意客体相关的ERP中，P1和N1受到强烈抑制。在包含单个客体的感知区域中未发现抑制现象，尽管在与被注意点（通过颜色选择）相关的ERP中发现了增强的选择负波。由于两个客体占据视觉空间的同一区域，P1/N1的抑制无法用基于空间的机制来解释，而是与视觉早期阶段基于客体的注意选择相一致。这些结果突出了感知组织在启用替代注意机制方面的作用。
