Watamaniuk S N
Department of Psychology, Northwestern University, Evanston, Illinois 60208.
J Opt Soc Am A. 1993 Jan;10(1):16-28. doi: 10.1364/josaa.10.000016.
Random-dot cinematograms in which each dot's successive movements are randomly drawn from a Gaussian distribution of directions can produce a percept of global coherent motion in a single direction. Discrimination of global direction was measured for various exposure durations, stimulus areas, and dot densities and bandwidths of the distribution of directions. Increasing the duration produced a greater improvement in performance than did increasing either the area or the density. Performance decreased as the distribution bandwidth increased. An ideal-observer model was developed, and the absolute efficiency for human direction discrimination was evaluated. Efficiencies were highest at large distribution bandwidths, with average efficiencies reaching 35%. A local-global noise model of direction discrimination, based on the ideal-observer model, containing a spatial and temporal integration limit as well as internal noise, was found to fit the human data well. The utility of ideal-observer analyses for psychophysical tasks and the interpretation of efficiencies is discussed.
随机点运动视差图中，每个点连续的运动方向是从高斯分布中随机抽取的，这样能产生单一方向上的全局连贯运动感知。针对不同的曝光持续时间、刺激区域以及方向分布的点密度和带宽，测量了全局方向辨别能力。与增加区域或密度相比，增加持续时间对性能的提升更大。随着分布带宽增加，性能下降。开发了一个理想观察者模型，并评估了人类方向辨别的绝对效率。在大分布带宽下效率最高，平均效率达到35%。基于理想观察者模型的方向辨别局部-全局噪声模型，包含空间和时间整合限制以及内部噪声，被发现能很好地拟合人类数据。讨论了理想观察者分析在心理物理学任务中的效用以及效率的解释。
