Spatiotemporal averaging of perceived brightness along an apparent motion trajectory.
Spatiotemporal averaging of perceived brightness along an apparent motion trajectory.
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DOI：
10.1167/11.7.5
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发表时间：
2011-06
影响因子：
1.8
通讯作者：
Takehiro Nagai;R. Beer;Erin Krizay;D. Macleod
中科院分区：
文献类型：
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作者：
Takehiro Nagai;R. Beer;Erin Krizay;D. Macleod
对象是视觉感知和识别的许多方面的关键功能单元。许多心理物理学实验支持“对象文件”的概念，该文件由基于连续视图的单个对象的特征组成，但很少有证据表明对象身份会影响表观亮度和颜色。在这项研究中，我们调查是否知觉识别连续的闪光刺激作为一个单一的移动物体的意见，可以影响亮度知觉。我们的目标刺激是由八个楔形部门。扇区沿环形轨迹沿着以不同的闪光间隔连续呈现。在约100毫秒的闪光间隔，印象是一个单一的移动物体进行长距离的明显运动。通过调制连续视图之间的亮度，我们测量了亮度调制的感知沿着这个长距离视运动的轨迹。在闪光间隔的运动知觉是最强的，亮度差被感知低估，和被迫选择亮度歧视阈值升高。此外，在这种条件下，观察者很难正确地将空间位置和楔形亮度联系起来。这些结果表明，被感知为单个物体的楔形物的不同亮度沿其表观运动轨迹被平均沿着。我们的刺激的大空间步长使得结果不太可能通过具有紧凑时空感受野（例如V1和V2神经元）的低水平机制的平均来解释;必须调用更高水平的全局运动或对象机制来解释平均效应。亮度平均和位置-亮度“绑定”的模糊性表明，视觉系统可以通过采用对象的特性在连续视图上不变的假设来避免快速计算表观亮度的一些成本。
Objects are critical functional units for many aspects of visual perception and recognition. Many psychophysical experiments support the concept of an "object file" consisting of characteristics attributed to a single object on the basis of successive views of it, but there has been little evidence that object identity influences apparent brightness and color. In this study, we investigated whether the perceptual identification of successive flashed stimuli as views of a single moving object could affect brightness perception. Our target stimulus was composed of eight wedge-shaped sectors. The sectors were presented successively at different inter-flash intervals along an annular trajectory. At inter-flash intervals of around 100 ms, the impression was of a single moving object undergoing long-range apparent motion. By modulating the luminance between successive views, we measured the perception of luminance modulation along the trajectory of this long-range apparent motion. At the inter-flash intervals where the motion perception was strongest, the luminance difference was perceptually underestimated, and forced-choice luminance discrimination thresholds were elevated. Moreover, under such conditions, it became difficult for the observer to correctly associate or "bind" spatial positions and wedge luminances. These results indicate that the different luminances of wedges that were perceived as a single object were averaged along its apparent motion trajectory. The large spatial step size of our stimulus makes it unlikely that the results could be explained by averaging in a low-level mechanism that has a compact spatiotemporal receptive field (such as V1 and V2 neurons); higher level global motion or object mechanisms must be invoked to account for the averaging effect. The luminance averaging and the ambiguity of position-luminance "binding" suggest that the visual system may evade some of the costs of rapidly computing apparent brightness by adopting the assumption that the characteristics of an object are invariant over successive views.