Collins Thérèse, Rolfs Martin, Deubel Heiner, Cavanagh Patrick
Biological Psychology and Neuropsychology, Hamburg University, Hamburg, Germany.
J Vis. 2009 May 29;9(5):29.1-9. doi: 10.1167/9.5.29.
The present study addresses the question of how objects are localized across saccades. In a task requiring participants to compare the location of a post-saccadic probe with the pre-saccadic target, we investigated the roles of saccade landing site and post-saccadic probe location. Saccade landing sites vary from trial to trial because of oculomotor error but can also be shifted by saccadic adaptation. Visual targets were extinguished during the saccade and reappeared after a short blank to counteract saccadic suppression of displacement. Performance in localizing targets after unadapted saccades was nearly veridical and independent of actual landing site, showing that trial-to-trial oculomotor error did not contribute to post-saccadic localization. This result suggests that much of the oculomotor error of saccades is included in the efference copy vector and this allows the recovery of a remapped target location that is often not foveal, but stable and accurate across trials. Displacement judgments relative to this remapped location will be independent of trial-to-trial variability in landing site. After adapted saccades, post-saccadic localization shifted in the direction opposite to adaptation but again, trial-by-trial landing site variability did not correlate with performance. This result suggests that the efference copy matches the planned upcoming saccade, be it adapted or not.
本研究探讨了物体如何在扫视过程中定位的问题。在一项要求参与者比较扫视后探测点与扫视前目标位置的任务中，我们研究了扫视着陆点和扫视后探测点位置的作用。由于眼动误差，扫视着陆点在不同试验中会有所变化，但也可能因扫视适应而发生偏移。在扫视过程中视觉目标会消失，并在短暂空白后重新出现，以抵消扫视对位移的抑制作用。未适应扫视后定位目标的表现几乎是准确的，且与实际着陆点无关，这表明逐次试验的眼动误差对扫视后定位没有影响。这一结果表明，扫视的大部分眼动误差包含在传出副本向量中，这使得能够恢复一个重新映射的目标位置，该位置通常不是中央凹的，但在不同试验中是稳定且准确的。相对于这个重新映射位置的位移判断将与着陆点的逐次试验变异性无关。适应扫视后，扫视后的定位在与适应相反的方向上发生偏移，但同样，逐次试验的着陆点变异性与表现无关。这一结果表明，传出副本与计划中的即将进行的扫视相匹配，无论其是否适应。
