Orban G A, Van Calenbergh F, De Bruyn B, Maes H
J Opt Soc Am A. 1985 Nov;2(11):1836-47. doi: 10.1364/josaa.2.001836.
Just-noticeable differences (jnd's) in velocity were measured as a function of reference velocity for central and peripheral vision. The velocity discrimination curves plotting jnd's in velocity, expressed as Weber fractions, as a function of reference velocity were U shaped at all eccentricities. Under almost every stimulus condition the increase in jnd in velocity with increasing eccentricity was significantly larger at low reference velocities than at high reference velocities. Consequently the shift toward higher velocities with increasing eccentricity was much clearer for the lower end of the velocity-discrimination curve than for the upper end. These results are in agreement with the predictions derived from the response characteristics of velocity-tuned cells. Control experiments involving direction discrimination have shown that the impossibility of making fine velocity judgments at high speeds is due not to too weak a contrast for the stimulus motion to be visible but to a limitation in the neural apparatus analyzing velocity.
针对中央视觉和周边视觉，测量了速度方面的恰可察觉差异（jnd），并将其作为参考速度的函数。以韦伯分数表示的速度辨别曲线，即速度方面的jnd作为参考速度的函数，在所有偏心率下均呈U形。在几乎每种刺激条件下，速度jnd随偏心率增加的幅度在低参考速度下比在高参考速度下显著更大。因此，对于速度辨别曲线的下端，随着偏心率增加向更高速度的偏移比上端要清晰得多。这些结果与从速度调谐细胞的反应特性得出的预测一致。涉及方向辨别的对照实验表明，在高速下无法做出精确速度判断，并非是由于刺激运动的对比度太弱以至于不可见，而是由于分析速度的神经机制存在局限性。
