Harris C M
Department of Ophthalmology, Children's Hospital, London, England.
Vision Res. 1995 Mar;35(5):691-701. doi: 10.1016/0042-6989(94)00163-g.
Visually guided saccades to single targets undershoot by about 10% of the target distance, and require additional secondary saccades to foveate the target. We examine theoretically the hypothesis that undershooting is an economical strategy for maximizing the time for clear vision by minimizing saccadic flight-time. Using a simple stochastic model, Monte-Carlo simulations show that when the standard deviation of saccadic error is about 10% of the target distance the optimal gain of primary saccades is about 0.93-0.97 depending on the main sequence for saccade duration. When the standard deviation of saccadic error is large, as occurs in the human infant, the optimal gain decreases to about 0.6, which agrees with empirical observations. We conclude that saccadic undershoot is consistent with an adaptive controller that attempts to minimize total saccadic flight-time during sequences, rather than retinal error. The ethology and physiology of such a controller is discussed in the context of visual scanning and visual development.
对单个目标的视觉引导扫视会比目标距离短大约10%，并且需要额外的二次扫视才能使目标成像于中央凹。我们从理论上检验了这样一个假设：扫视不足是一种通过最小化扫视飞行时间来最大化清晰视觉时间的经济策略。使用一个简单的随机模型，蒙特卡洛模拟表明，当扫视误差的标准差约为目标距离的10%时，根据扫视持续时间的主序列，初次扫视的最优增益约为0.93 - 0.97。当扫视误差的标准差很大时，就像在人类婴儿中出现的情况那样，最优增益会降至约0.6，这与实证观察结果相符。我们得出结论，扫视不足与一个试图在序列中最小化总扫视飞行时间而非视网膜误差的自适应控制器是一致的。这种控制器的行为学和生理学在视觉扫描和视觉发育的背景下进行了讨论。
