Lappin Joseph S, Tadin Duje, Nyquist Jeffrey B, Corn Anne L
Vanderbilt Vision Research Center and Department of Psychology, Vanderbilt University, Nashville, TN, USA.
J Vis. 2009 Jan 22;9(1):30.1-14. doi: 10.1167/9.1.30.
We evaluated spatial displacement and temporal duration thresholds for discriminating the motion direction of gratings for a broad range of speeds (0.06 degrees/s to 30 degrees/s) in fovea and at +/-30 degrees eccentricity. In general, increased speed yielded lower duration thresholds but higher displacement thresholds. In most conditions, these effects of speed were comparable in fovea and periphery, yielding relatively similar thresholds not correlated with decreased peripheral acuity. The noteworthy exceptions were interactive effects at slow speeds: (1) Displacement thresholds for peripheral motion were affected by acuity limits for speeds below 0.5 degrees/s. (2) Low-vision observers with congenital nystagmus had elevated thresholds for peripheral motion and slow foveal motion but resembled typically sighted observers for foveal motions at speeds above 1 degree/s. (3) Suppressive center-surround interactions were absent below 0.5 degrees/s and their strength increased with speed. Overall, these results indicate qualitatively different sensitivities to slow and fast motions. Thresholds for very slow motion are limited by spatial resolution, while thresholds for fast motion are probably limited by temporal resolution.
我们评估了在中央凹以及±30度偏心率处，区分不同速度（0.06度/秒至30度/秒）光栅运动方向的空间位移和时间持续阈值。一般来说，速度增加会导致持续阈值降低，但位移阈值升高。在大多数情况下，速度的这些影响在中央凹和周边区域相当，产生相对相似的阈值，且与周边视力下降无关。值得注意的例外是低速时的交互作用：（1）对于速度低于0.5度/秒的周边运动，位移阈值受视力限制的影响。（2）患有先天性眼球震颤的低视力观察者，其周边运动和中央凹缓慢运动的阈值升高，但在速度高于1度/秒时，中央凹运动的阈值与视力正常的观察者相似。（3）在低于0.5度/秒时不存在抑制性中心 - 周边相互作用，且其强度随速度增加。总体而言，这些结果表明对慢速和快速运动的敏感性在性质上有所不同。非常慢速运动的阈值受空间分辨率限制，而快速运动的阈值可能受时间分辨率限制。
