Wu Chia-Chien, Kwon Oh-Sang, Kowler Eileen
Department of Psychology, Rutgers University, 152 Frelinghuysen Road, Piscataway, NJ 08854, USA.
Vision Res. 2010 Oct 12;50(21):2142-57. doi: 10.1016/j.visres.2010.08.008. Epub 2010 Aug 13.
Strategies of saccadic planning must take into account both the required level of accuracy of the saccades, and the time and resources needed to plan and execute the movements. To determine relationships between accuracy and time, we studied sequences of saccades made to scan a set of stationary targets located at the corners of an imaginary square. Target separation and size varied. The time taken to complete saccadic sequences increased with the required level of precision, in agreement with the classical Fitts's Law (1954) relationship. This was mainly due to the use of error-correcting secondary saccades, whose frequency increased with target separation and decreased with target size. Increases in the time spent fixating near each target did not increase the accuracy of the next primary saccade in the sequence. Instead, secondary saccades were the principal means of correcting landing errors of primary saccades. The results are consistent with a scanning strategy that discourages careful planning of individual saccades in favor of increasing the rate of saccadic production (i.e., exploration), using secondary saccades as needed to correct saccadic landing errors.
扫视计划的策略必须同时考虑扫视所需的精确程度，以及计划和执行这些动作所需的时间和资源。为了确定精确性与时间之间的关系，我们研究了为扫描位于一个假想正方形角落的一组固定目标而进行的扫视序列。目标间距和大小各不相同。完成扫视序列所需的时间随着所需精确程度的提高而增加，这与经典的菲茨定律（1954年）的关系一致。这主要是由于使用了纠错性的二次扫视，其频率随着目标间距的增加而增加，随着目标大小的减小而降低。在每个目标附近注视时间的增加并没有提高序列中下一个初级扫视的精确性。相反，二次扫视是纠正初级扫视着陆误差的主要手段。这些结果与一种扫视策略一致，该策略不鼓励对单个扫视进行仔细规划，而是倾向于提高扫视产生的速率（即探索），并在需要时使用二次扫视来纠正扫视着陆误差。
