McSorley Eugene, Haggard Patrick, Walker Robin
School of Psychology and Clinical Language Sciences, University of Reading, Harry Pitt Building, Earley Gate, Reading RG6 6AL, UK.
Vision Res. 2009 Mar;49(6):608-14. doi: 10.1016/j.visres.2009.01.015. Epub 2009 Feb 6.
Selecting a stimulus as the target for a goal-directed movement involves inhibiting other competing possible responses. Inhibition has generally proved hard to study behaviorally, because it results in no measurable output. The effect of distractors on the shape of oculomotor and manual trajectories provide evidence of such inhibition. Individual saccades may deviate initially either towards, or away from, a competing distractor - the direction and extent of this deviation depends upon saccade latency, target predictability and the target to distractor separation. The experiment reported here used these effects to show how inhibition of distractor locations develops over time. Distractors could be presented at various distances from unpredictable and predictable targets in two separate experiments. The deviation of saccade trajectories was compared between trials with and without distractors. Inhibition was measured by saccade trajectory deviation. Inhibition was found to increase as the distractor distance from target decreased but was found to increase with saccade latency at all distractor distances (albeit to different peaks). Surprisingly, no differences were found between unpredictable and predictable targets perhaps because our saccade latencies were generally long (approximately 260-280 ms.). We conclude that oculomotor inhibition of saccades to possible target objects involves the same mechanisms for all distractor distances and target types.
选择一个刺激作为目标导向运动的对象需要抑制其他可能的竞争反应。一般来说，抑制作用很难通过行为学进行研究，因为它不会产生可测量的输出。干扰物对眼球运动轨迹和手动轨迹形状的影响为此类抑制作用提供了证据。单个扫视运动最初可能会朝着或远离竞争干扰物发生偏差——这种偏差的方向和程度取决于扫视潜伏期、目标可预测性以及目标与干扰物之间的距离。本文报道的实验利用这些效应来展示对干扰物位置的抑制作用是如何随时间发展的。在两个独立实验中，干扰物可以呈现于与不可预测和可预测目标的不同距离处。比较了有干扰物和无干扰物试验中扫视轨迹的偏差。通过扫视轨迹偏差来测量抑制作用。结果发现，抑制作用随着干扰物与目标距离的减小而增强，但在所有干扰物距离下，抑制作用都随着扫视潜伏期的增加而增强（尽管达到的峰值不同）。令人惊讶的是，不可预测和可预测目标之间未发现差异，可能是因为我们的扫视潜伏期通常较长（约260 - 280毫秒）。我们得出结论，对于所有干扰物距离和目标类型，眼球运动对可能的目标物体的扫视抑制作用涉及相同的机制。
