Pianta M J, Kalloniatis M
Department of Optometry and Vision Sciences, University of Melbourne, Victoria, Australia.
Percept Psychophys. 1998 Apr;60(3):491-502. doi: 10.3758/bf03206869.
The characteristics of artificially induced anisometropic suppression were investigated in observers with normal and abnormal binocular vision (anisometropic amblyopia) by using a simple reaction time paradigm. Reaction time was measured as a function of stimulus intensity for various stimulus durations. For all conditions, the reaction time increased as stimulus intensity decreased toward threshold. We found that traditional techniques for modeling this trend were inadequate, so we developed a simple visuogram method for comparing these functions. Using this technique, reaction time versus intensity functions are shown to be shape-invariant for all conditions examined. This means that, although reaction times are longer during induced anisometropic suppression or in anisometropic amblyopia, they are the same if contrast is normalized to equate threshold. The shape-invariant nature of these functions is also consistent with the notion that a single mechanism mediates detection under these conditions. Temporal summation was investigated at both threshold (method of limits) and suprathreshold (criterion reaction time) levels. Again, because of shape invariance, the suprathreshold results mirror the threshold results. The critical duration (the duration at the intersection of the complete summation and zero summation regions) is not affected by any of the conditions. However, the critical intensity (the intensity for the zero summation region) is higher for the amblyopic eyes, as compared with the normal or nonamblyopic eyes. Induced anisometropic suppression always increases the critical intensity, with a smaller increase occurring for the amblyopic eyes. This suggests that amblyopic eyes do not have a need for strong suppression.
通过使用简单的反应时范式，在双眼视觉正常和异常（屈光参差性弱视）的观察者中研究了人工诱导的屈光参差性抑制的特征。测量了不同刺激持续时间下反应时随刺激强度的变化。在所有条件下，随着刺激强度向阈值降低，反应时增加。我们发现传统的模拟这种趋势的技术并不充分，因此我们开发了一种简单的视功能图方法来比较这些函数。使用这种技术，反应时与强度函数在所有检查条件下都显示出形状不变性。这意味着，尽管在诱导的屈光参差性抑制期间或屈光参差性弱视中反应时较长，但如果将对比度归一化以使其阈值相等，则它们是相同的。这些函数的形状不变性也与在这些条件下单一机制介导检测的观点一致。在阈值（极限法）和阈上（标准反应时）水平都研究了时间总和。同样，由于形状不变性，阈上结果反映了阈值结果。临界持续时间（完全总和与零总和区域相交处的持续时间）不受任何条件的影响。然而，与正常或非弱视眼相比，弱视眼的临界强度（零总和区域的强度）更高。诱导的屈光参差性抑制总是会增加临界强度，弱视眼的增加幅度较小。这表明弱视眼不需要强烈的抑制。
