Kitterle F L, Christman S, Hellige J B
Department of Psychology, University of Toledo, OH 43606.
Percept Psychophys. 1990 Oct;48(4):297-306. doi: 10.3758/bf03206680.
The processing of sine-wave gratings presented to the left and right visual fields was examined in four experiments. Subjects were required either to detect the presence of a grating (Experiments 1 and 2) or to identify the spatial frequency of a grating (Experiments 3 and 4). Orthogonally to this, the stimuli were presented either at threshold levels of contrast (Experiments 1 and 3) or at suprathreshold levels (Experiments 2 and 4). Visual field and spatial frequency interacted when the task required identification of spatial frequency, but not when it required only stimulus detection. Regardless of contrast level (threshold, suprathreshold), high-frequency gratings were identified more readily in the right visual field (left hemisphere), whereas low-frequency gratings showed no visual field difference (Experiment 3) or were identified more readily in the left visual field (right hemisphere) (Experiment 4). Thus, hemispheric asymmetries in the processing of spatial frequencies depend on the task. These results support Sergent's (1982) spatial frequency hypothesis, but only when the computational demands of the task exceed those required for the simple detection of the stimuli.
在四项实验中，研究了呈现给左右视野的正弦波光栅的处理情况。要求受试者要么检测光栅的存在（实验1和2），要么识别光栅的空间频率（实验3和4）。与此正交的是，刺激要么以对比度的阈值水平呈现（实验1和3），要么以上阈值水平呈现（实验2和4）。当任务需要识别空间频率时，视野和空间频率相互作用，但当任务仅需要刺激检测时则不然。无论对比度水平（阈值、上阈值）如何，高频光栅在右视野（左半球）中更容易被识别，而低频光栅在视野上没有差异（实验3），或者在左视野（右半球）中更容易被识别（实验4）。因此，空间频率处理中的半球不对称性取决于任务。这些结果支持塞尔让（1982）的空间频率假说，但仅当任务的计算需求超过简单检测刺激所需的需求时才成立。 。
