May J G, Brown J M, Scott S, Donlon M
University of New Orleans, LA 70148.
Percept Psychophys. 1990 Jun;47(6):563-7. doi: 10.3758/bf03203108.
Periodic stimuli such as sine-wave gratings and checkerboard patterns have been used in many studies of visual perception. It is well known that with such stimuli, visual persistence increases as spatial frequency increases and as contrast decreases. It is not clear, however, that similar relationships obtain for aperiodic stimuli such as natural images. Digitized images of objects (a face and a vase) were submitted to two-dimensional Fourier analysis. Four pairs of spatial frequency band-limited images were created for each image. Each pair consisted of a normal (NP) and a scrambled (SP) phase version, with the magnitude spectrum and space-averaged luminance the same within each pair. Filter bandwidths were one octave wide. Threshold persistence was measured for each spatially filtered image. Visual persistence for SP images increased significantly as spatial frequency increased, whereas no significant differences were found for NP images. This suggests that the temporal processing of complex, aperiodic visual images is influenced by the spatial frequency and contrast of local features within the image and cannot be predicted by space-averaged estimates of contrast and spatial frequency.
诸如正弦波光栅和棋盘图案等周期性刺激已在许多视觉感知研究中被使用。众所周知，对于此类刺激，视觉暂留会随着空间频率的增加和对比度的降低而增强。然而，对于诸如自然图像等非周期性刺激是否存在类似关系尚不清楚。将物体（一张脸和一个花瓶）的数字化图像进行二维傅里叶分析。为每个图像创建了四对空间频率带限图像。每对图像由一个正常（NP）相位版本和一个打乱（SP）相位版本组成，每对图像中的幅度谱和空间平均亮度相同。滤波器带宽为一个八度宽。对每个空间滤波后的图像测量阈值暂留。SP图像的视觉暂留随着空间频率的增加而显著增加，而NP图像未发现显著差异。这表明复杂的非周期性视觉图像的时间处理受到图像中局部特征的空间频率和对比度的影响，并且无法通过对比度和空间频率的空间平均估计来预测。
