Heinen Stephen J, Badler Jeremy B, Watamaniuk Scott N J
Smith-Kettlewell Eye Research Institute , San Francisco, California.
Department of Psychology, Wright State University , Dayton, Ohio.
J Neurophysiol. 2018 Aug 1;120(2):489-496. doi: 10.1152/jn.00418.2017. Epub 2018 Apr 18.
Models of smooth pursuit eye movements stabilize an object's retinal image, yet pursuit is peppered with small, destabilizing "catch-up" saccades. Catch-up saccades might help follow a small, spot stimulus used in most pursuit experiments, since fewer of them occur with large stimuli. However, they can return when a large stimulus has a small central feature. It may be that a central feature on a large object automatically recruits the saccadic system. Alternatively, a cognitive choice is made that the feature is the pursuit goal, and the saccadic system is then recruited to pursue it. Observers pursued a 5-dot stimulus composed of a central dot surrounded by four peripheral dots arranged as a diamond. An attention task specified the pursuit goal as either the central element, or the diamond gestalt. Fewer catch-up saccades occurred with the Gestalt goal than with the central goal, although the additional saccades with the central goal neither enhanced nor impeded pursuit. Furthermore, removing the central element from the diamond goal further reduced catch-up saccade frequency, indicating that the central element automatically triggered some saccades. Higher saccade frequency was not simply due to narrowly focused attention, since attending a small peripheral diamond during pursuit elicited fewer saccades than attending the diamond positioned foveally. The results suggest some saccades are automatically elicited by a small central element, but when it is chosen as the pursuit goal the saccadic system is further recruited to pursue it. NEW & NOTEWORTHY Smooth-pursuit eye movements stabilize retinal image motion to prevent blur. Curiously, smooth pursuit is frequently supplemented by small catchup saccades that could reduce image clarity. Catchup saccades might only be needed to pursue small laboratory stimuli, as they are infrequent during large object pursuit. Yet large objects with central features revive them. Here, we show that voluntarily selecting a feature as the pursuit goal elicits saccades that do not help pursuit.
平稳跟踪眼球运动模型可稳定物体的视网膜图像,但跟踪过程中会穿插一些微小的、破坏稳定性的“追赶”扫视。追赶扫视可能有助于跟踪大多数跟踪实验中使用的小光点刺激,因为大刺激引发的追赶扫视较少。然而,当大刺激具有小的中心特征时,追赶扫视又会出现。可能是大物体上的中心特征自动激活了扫视系统。或者,做出了一种认知选择,即该特征是跟踪目标,然后激活扫视系统来对其进行跟踪。观察者跟踪一个由中央点和四个排列成菱形的周边点组成的五点刺激。一项注意力任务将跟踪目标指定为中央元素或菱形整体。与中央目标相比,整体目标引发的追赶扫视较少,尽管中央目标引发的额外扫视既没有增强也没有阻碍跟踪。此外,从菱形目标中移除中央元素进一步降低了追赶扫视频率,表明中央元素会自动触发一些扫视。较高的扫视频率并非仅仅由于注意力高度集中,因为在跟踪过程中注视小的周边菱形时引发的扫视比注视位于中央凹的菱形时要少。结果表明,一些扫视是由小的中央元素自动引发的,但当它被选作跟踪目标时,扫视系统会进一步被激活来对其进行跟踪。新发现与值得注意之处 平稳跟踪眼球运动可稳定视网膜图像运动以防止模糊。奇怪的是,平稳跟踪经常会辅以可能降低图像清晰度的小追赶扫视。追赶扫视可能仅在跟踪小的实验室刺激时才需要,因为在跟踪大物体时它们很少出现。然而,具有中心特征的大物体会使它们再次出现。在这里,我们表明,自愿选择一个特征作为跟踪目标会引发无助于跟踪的扫视。