Montaser-Kouhsari Leila, Rajimehr Reza
School of Cognitive Sciences, Institute for Studies in Theoretical Physics and Mathematics, Tehran, Iran.
J Vis. 2004 May 20;4(6):434-44. doi: 10.1167/4.6.3.
Selective visual attention modulates neuronal activation in various cortical areas. This type of neuronal modulation could happen even in the early stages of visual processing where specific attributes of visual stimuli are processed. It has been shown that different forms of visual aftereffects, such as tilt aftereffect, motion aftereffect, and figural aftereffect, are modulated by attention. In this study, we investigated the effect of visual attention on adaptation to illusory lines. In the first experiment, orientation selective adaptation to a peripheral illusory line was measured in three conditions: (1) poor attention condition in which subjects performed a dual task (even-odd judgment) at the fixation point during the adaptation period, (2) partial attention condition in which subjects only observed successively presented digits at the fixation point and did not perform the task during the adaptation period, and (3) full attention condition in which no visual stimuli were presented at the fixation point. Results showed that the magnitude of adaptation systematically decreased as the attentional load at the fixation point increased. In the second experiment, two transparent illusory contours were presented during the adaptation period, and tilt aftereffects to attended and non-attended illusory lines were compared. The magnitude of tilt aftereffect to the attended illusory line was significantly greater than that to the non-attended illusory line even when non-attended illusory contour was more visually salient. Because visual areas V2 and V1 are the first stage in the processing of illusory contours, we could conclude that visual attention has modulatory effects on the activation of neurons in these areas.
选择性视觉注意调节各个皮层区域的神经元激活。这种类型的神经元调节甚至可能发生在视觉处理的早期阶段，即视觉刺激的特定属性被处理的阶段。研究表明，不同形式的视觉后效，如倾斜后效、运动后效和图形后效，都会受到注意的调节。在本研究中，我们调查了视觉注意对虚幻线条适应的影响。在第一个实验中，在三种条件下测量了对外周虚幻线条的方向选择性适应：（1）注意力分散条件，即受试者在适应期内在注视点执行双重任务（奇偶判断）；（2）部分注意力条件，即受试者仅观察在注视点相继呈现的数字，在适应期不执行任务；（3）全神贯注条件，即注视点不呈现视觉刺激。结果表明，随着注视点注意力负荷的增加，适应程度系统性降低。在第二个实验中，在适应期呈现两个透明的虚幻轮廓，并比较了对被注意和未被注意的虚幻线条的倾斜后效。即使未被注意的虚幻轮廓在视觉上更显著，对被注意的虚幻线条的倾斜后效程度也显著大于对未被注意的虚幻线条的倾斜后效程度。由于视觉区域V2和V1是虚幻轮廓处理的第一阶段，我们可以得出结论，视觉注意对这些区域的神经元激活具有调节作用。
