Baldo Marcus V C, Kihara Alexandre H, Namba Janaina, Klein Stanley A
Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, SP, Brazil.
Perception. 2002;31(1):17-30. doi: 10.1068/p3302.
If a pair of dots, diametrically opposed to each other, is flashed in perfect alignment with another pair of dots rotating about the visual fixation point, most observers perceive the rotating dots as being ahead of the flashing dots (flash-lag effect). This psychophysical effect was first interpreted as the result of a perceptual extrapolation of the position of the moving dots. Also, it has been conceived as the result of differential visual latencies between flashing and moving stimuli, arising from purely sensory factors and/or expressing the contribution of attentional mechanisms as well. In a series of two experiments, we had observers judge the relative position between rotating and static dots at the moment a temporal marker was presented in the visual field. In experiment 1 we manipulated the nature of the temporal marker used to prompt the alignment judgment. This resulted in three main findings: (i) the flash-lag effect was observed to depend on the visual eccentricity of the flashing dots; (ii) the magnitude of the flash-lag effect was not dependent on the offset of the flashing dot; and (iii) the moving stimulus, when suddenly turned off, was perceived as lagging behind its disappearance location. Taken altogether, these results suggest that neither visible persistence nor motion extrapolation can account for the perceptual flash-lag phenomenon. The participation of attentional mechanisms was investigated in experiment 2, where the magnitude of the flash-lag effect was measured under both higher and lower predictability of the location of the flashing dot. Since the magnitude of the flash-lag effect significantly increased with decreasing predictability, we conclude that the observer's attentional set can modulate the differential latencies determining this perceptual effect. The flash-lag phenomenon can thus be conceived as arising from differential visual latencies which are determined not only by the physical attributes of the stimulus, such as its luminance or eccentricity, but also by attentional mechanisms influencing the delays involved in the perceptual processing.
如果一对彼此相对的点与另一围绕视觉注视点旋转的点对以完美对齐的方式闪烁，大多数观察者会感觉到旋转的点比闪烁的点超前（闪光滞后效应）。这种心理物理学效应最初被解释为对移动点位置进行感知外推的结果。此外，它还被认为是闪烁刺激和移动刺激之间视觉延迟差异的结果，这种差异源于纯粹的感官因素和/或也体现了注意力机制的作用。在一系列两个实验中，我们让观察者在视野中呈现时间标记的时刻判断旋转点和静态点之间的相对位置。在实验1中，我们操纵了用于提示对齐判断的时间标记的性质。这产生了三个主要发现：（i）观察到闪光滞后效应取决于闪烁点的视觉离心率；（ii）闪光滞后效应的大小不取决于闪烁点的偏移；（iii）移动刺激突然关闭时，会被感知为滞后于其消失位置。总体而言，这些结果表明，可见持久性和运动外推都无法解释感知闪光滞后现象。在实验2中研究了注意力机制的参与情况，在该实验中，在闪烁点位置的可预测性较高和较低两种情况下都测量了闪光滞后效应的大小。由于闪光滞后效应的大小随着可预测性的降低而显著增加，我们得出结论，观察者的注意力设定可以调节决定这种感知效应的差异延迟。因此，闪光滞后现象可以被认为是由差异视觉延迟引起的，这种延迟不仅由刺激的物理属性（如亮度或离心率）决定，还由影响感知处理中所涉及延迟的注意力机制决定。
