Casco Clara, Robol Valentina, Grassi Massimo, Venturini Cristina
Department of General Psychology, University of Padua, Padua, Italy.
Vision Res. 2012 Aug 15;67:37-43. doi: 10.1016/j.visres.2012.07.001. Epub 2012 Jul 11.
In the present study we examined the effect of positional noise on spatial resolution in younger and older observers. We used a yes/no discrimination task in which observers indicated whether the size of two gaps in a Landolt-C-like contour was the same or not. The proportion of trials observers perceived one gap larger was measured when gaps-position was fixed (low positional noise) and random (high positional noise). Specifically, we compared, across conditions and groups, the values of threshold, lower and upper asymptote of the psychometric function. In the younger group, noise does not prevent detection of gap-size difference although sensitivity is lower, as revealed by higher threshold and lower upper asymptote, i.e., the proportion of responses "I see a larger gap" at the largest gap-size difference (asymptotic performance). In the older group detection is prevented, as revealed by threshold, lower and upper asymptote data. This may be because, at stimulus onset, high positional noise has associated coarse filter analysers averaging across the two gaps, which cannot be switched off.
在本研究中，我们考察了位置噪声对年轻和年长观察者空间分辨率的影响。我们采用了一种是/否辨别任务，让观察者判断类似C型兰多尔特环的轮廓中两个缺口的大小是否相同。当缺口位置固定（低位置噪声）和随机（高位置噪声）时，测量观察者感知到一个缺口更大的试验比例。具体而言，我们在不同条件和组之间比较了心理测量函数的阈值、下限和上限渐近线的值。在年轻组中，尽管敏感性较低，但噪声并不妨碍对缺口大小差异的检测，这表现为较高的阈值和较低的上限渐近线，即在最大缺口大小差异时（渐近表现）“我看到一个更大的缺口”的反应比例。在老年组中，阈值、下限和上限渐近线数据表明检测受到了妨碍。这可能是因为，在刺激开始时，高位置噪声与对两个缺口进行平均的粗糙滤波器分析器相关联，而这些分析器无法关闭。
