Rivest J, Cavanagh P, Lassonde M
Psychology Department, Glendon College, Toronto, Ontario, Canada.
Neuropsychologia. 1994 Jan;32(1):69-76. doi: 10.1016/0028-3932(94)90069-8.
Interhemispheric depth comparisons were studied by requiring subjects to align in depth two textured plates, one presented to the left hemifield and the other to the right. Callosal agenesis subjects and neurologically-normal control subjects adjusted the plates so that they appeared to be at the same distance. Subjects viewed the plates monocularly or binocularly while keeping their head still, moving it side-to-side or moving it up and down. Subjects fixated a target located between the two plates while performing the task. For all subjects, the results showed that the deviations from veridical settings were significantly smaller for the binocular than for the monocular viewing conditions. Moreover, there were no significant differences among the three binocular viewing conditions (horizontal, vertical or no head movement), indicating that neither vertical nor horizontal motion parallax improves the precision of depth judgement when binocular disparity is available. These results further suggest that the precision of interhemispheric comparison for binocular depth is not affected by the absence of the corpus callosum. Looking at the plates monocularly, the control subjects judge the relative depth between the plates more precisely when they moved their head than when they kept it still. These results show that motion parallax is a useful depth cue when relative motion is extracted from different hemifields. Unlike the control subjects, the callosal agenesis subjects did not judge the relative depth between the plates more precisely when they moved their head than when they kept it still. These results show that interhemispheric comparison of depth using relative motion is not possible without the corpus callosum.
通过要求受试者在深度上对齐两个有纹理的盘子来研究半球间深度比较，一个盘子呈现给左半视野，另一个呈现给右半视野。胼胝体发育不全的受试者和神经学上正常的对照受试者调整盘子，使它们看起来在相同的距离。受试者在保持头部静止、左右移动或上下移动时单眼或双眼观察盘子。在执行任务时，受试者注视位于两个盘子之间的一个目标。对所有受试者来说，结果表明，与单眼观察条件相比，双眼观察条件下与真实设置的偏差明显更小。此外，三种双眼观察条件（水平、垂直或头部不移动）之间没有显著差异，这表明当双眼视差可用时，垂直或水平运动视差都不会提高深度判断的精度。这些结果进一步表明，双眼深度的半球间比较精度不受胼胝体缺失的影响。单眼观察盘子时，对照受试者在移动头部时比保持头部静止时能更精确地判断盘子之间的相对深度。这些结果表明，当从不同半视野提取相对运动时，运动视差是一种有用的深度线索。与对照受试者不同，胼胝体发育不全的受试者在移动头部时并不比保持头部静止时更精确地判断盘子之间的相对深度。这些结果表明，没有胼胝体就不可能利用相对运动进行半球间深度比较。
