Ludwig Casimir J H, Gilchrist Iain D
Department of Experimental Psychology, University of Bristol, Bristol, England.
Behav Res Methods Instrum Comput. 2002 Nov;34(4):618-24. doi: 10.3758/bf03195490.
Saccade curvature is becoming a popular measure for detecting the presence of competing saccadic motor programs. Several different methods of quantifying saccade curvature have been employed. In the present study, we compared these metrics with each other and with novel measures based on curve fitting. Initial deviation metrics were only moderately associated with the more widely used metric of maximum curvature. The latter was strongly related to a recently developed area-based measure and to the novel methods based on second- and third-order polynomial fits. The curve-fitting methods showed that although most saccades curved in only one direction, there was a population of trajectories with both a maximum and a minimum (i.e., double-curved saccades). We argue that a curvature metric based on a quadratic polynomial fit deals effectively with both types of trajectories and, because it is based on all the samples of a saccade, is less susceptible to sampling noise.
扫视曲率正成为检测竞争性扫视运动程序存在的一种常用指标。已经采用了几种不同的量化扫视曲率的方法。在本研究中，我们将这些指标相互比较，并与基于曲线拟合的新指标进行比较。初始偏差指标与更广泛使用的最大曲率指标仅中度相关。后者与最近开发的基于面积的指标以及基于二阶和三阶多项式拟合的新方法密切相关。曲线拟合方法表明，虽然大多数扫视仅在一个方向上弯曲，但存在一部分轨迹既有最大值又有最小值（即双曲扫视）。我们认为，基于二次多项式拟合的曲率指标能有效处理这两种类型的轨迹，并且由于它基于扫视的所有样本，因此对采样噪声更不敏感。
