Hodos William, Ghim Mimi M, Potocki Alex, Fields Jessica N, Storm Thilo
Department of Psychology, University of Maryland, College Park 20742-4411, USA.
Doc Ophthalmol. 2002 Jan;104(1):107-18. doi: 10.1023/a:1014427615636.
Contrast sensitivity (CS) is often used to assess spatial and temporal vision in animals. Conventional behavioral psychophysical techniques are both time and labor intensive, whereas measurement of CS functions by means of the pattern electroretinogram (PERG) is considerably more rapid and efficient. Are the two methods comparable, however? To answer this question, contrast-sensitivity functions were obtained using both the PERG and behavioral psychophysics in the same subjects, which were White Carneaux pigeons. The stimuli, in both methods, were phase-reversing, contrast-modulated sweeps of sinusoidal gratings. The PERG-CS functions were recorded via corneal electrodes and the behavioral data were collected using a modified staircase method that used moderate food deprivation and food reward. The results indicated that the PERG-CS functions had comparable bandwidth and peak spatial frequency to the behavioral CS functions. The PERG-CS functions, however, were lower on average than the behavioral curves by about 54%. The visual acuity of the two methods, as estimated from the high-frequency cutoff of the CS functions, differed by 37%. Both of these values are roughly consistent with the square root of 2 advantage of binocular viewing (behavioral method) over monocular viewing (PERG method). In addition, the peak spatial frequency showed a decrease of 0.125 c/deg with the PERG method and bandwidth was reduced by approximately 0.5 octave. These findings suggest that the PERG is an acceptable alternative to behavioral measurement of CS functions, especially in animal psychophysics, if one takes into account the underestimation of CS by the PERG method and the small changes in peak spatial frequency and bandwidth.
对比敏感度（CS）常用于评估动物的空间和时间视觉。传统的行为心理物理学技术既耗时又费力，而通过图形视网膜电图（PERG）测量CS功能则要快得多且效率更高。然而，这两种方法具有可比性吗？为了回答这个问题，我们在同一受试对象——白卡诺鸽身上，同时使用PERG和行为心理物理学方法获得了对比敏感度函数。在这两种方法中，刺激均为正弦光栅的相位反转、对比度调制扫描。通过角膜电极记录PERG-CS功能，使用改良的阶梯法收集行为数据，该方法采用适度的食物剥夺和食物奖励。结果表明，PERG-CS功能与行为CS功能具有可比的带宽和峰值空间频率。然而，PERG-CS功能平均比行为曲线低约54%。根据CS功能的高频截止估算，两种方法的视敏度相差37%。这两个值大致与双眼观察（行为方法）相对于单眼观察（PERG方法）的√2优势一致。此外，PERG方法的峰值空间频率下降了0.125 c/deg，带宽减少了约0.5倍频程。这些发现表明，如果考虑到PERG方法对CS的低估以及峰值空间频率和带宽的微小变化，PERG是行为测量CS功能的一种可接受的替代方法，尤其是在动物心理物理学中。
