Baitch L W, Levi D M
University of Houston College of Optometry, TX 77004.
Vision Res. 1989;29(1):27-35. doi: 10.1016/0042-6989(89)90171-5.
We describe a psychophysical method for assessing binocular integration using dichoptically-presented uniform fields. By temporally modulating uniform field luminances at different frequencies between the eyes, a rhythmic beat is produced--a visual percept characterized by undulations in luminance at a frequency equal to the arithmetic difference between the two monocular stimulus frequencies. Using a signal detection paradigm, we studied the beat as a function of modulation depth in normal and binocularly deficient subjects. Normal subjects easily detected the beat, even at low modulation depths, while stereoblind subjects (with stereoacuity worse than 2000 sec arc) failed to detect beats at any modulation depth or with any combination of stimulus frequencies tested. The beat provides evidence for the confluence of monocular signals into binocular integrating mechanisms. Our results therefore suggest that the status of functioning binocular mechanisms is related to the detectability of the beat. This uniform-field stimulus does not require accurate accommodation, fixation, vergence or high spatial resolution, thus making this technique particularly attractive for the study of binocular interaction in developing infants and in binocularly deficient adults.
我们描述了一种使用双眼分别呈现的均匀场来评估双眼整合的心理物理学方法。通过在双眼之间以不同频率对均匀场亮度进行时间调制，会产生一种节律性搏动——一种视觉感知，其特征是亮度以等于两个单眼刺激频率算术差的频率波动。使用信号检测范式，我们研究了正常受试者和双眼功能缺陷受试者中这种搏动与调制深度的关系。正常受试者即使在低调制深度下也能轻松检测到搏动，而立体盲受试者（立体视锐度差于2000秒弧度）在任何调制深度或任何测试的刺激频率组合下都无法检测到搏动。这种搏动为单眼信号汇聚到双眼整合机制提供了证据。因此，我们的结果表明，双眼功能机制的状态与搏动的可检测性有关。这种均匀场刺激不需要精确的调节、注视、辐辏或高空间分辨率，因此使得该技术对于研究发育中的婴儿和双眼功能缺陷的成年人的双眼相互作用特别有吸引力。
