Centre for Vision Research and Vision: Science to Applications (VISTA) Program, York University, Toronto, ON, Canada.
Department of Psychology, York University, Toronto, ON, Canada.
J Vis. 2024 Jul 2;24(7):17. doi: 10.1167/jov.24.7.17.
Allocentric landmarks have an implicit influence on aiming movements, but it is not clear how an explicit instruction (to aim relative to a landmark) influences reach accuracy and precision. Here, 12 participants performed a task with two instruction conditions (egocentric vs. allocentric) but with similar sensory and motor conditions. Participants fixated gaze near the center of a display aligned with their right shoulder while a target stimulus briefly appeared alongside a visual landmark in one visual field. After a brief mask/memory delay the landmark then reappeared at a different location (same or opposite visual field), creating an ego/allocentric conflict. In the egocentric condition, participants were instructed to ignore the landmark and point toward the remembered location of the target. In the allocentric condition, participants were instructed to remember the initial target location relative to the landmark and then reach relative to the shifted landmark (same or opposite visual field). To equalize motor execution between tasks, participants were instructed to anti-point (point to the visual field opposite to the remembered target) on 50% of the egocentric trials. Participants were more accurate and precise and quicker to react in the allocentric condition, especially when pointing to the opposite field. We also observed a visual field effect, where performance was worse overall in the right visual field. These results suggest that, when egocentric and allocentric cues conflict, explicit use of the visual landmark provides better reach performance than reliance on noisy egocentric signals. Such instructions might aid rehabilitation when the egocentric system is compromised by disease or injury.
非自我中心地标对瞄准运动有隐含影响，但尚不清楚明确的指示（相对于地标进行瞄准）如何影响到达准确性和精度。在这里，12 名参与者在两种指示条件（自我中心与非自我中心）下进行了一项任务，但具有相似的感觉和运动条件。参与者将目光固定在与右肩对齐的显示器中心附近，而目标刺激物在一个视野中的视觉地标旁边短暂出现。短暂的掩蔽/记忆延迟后，地标出现在不同的位置（相同或相反的视野），产生自我/非自我中心冲突。在自我中心条件下，参与者被指示忽略地标并指向目标的记忆位置。在非自我中心条件下，参与者被指示记住相对于地标初始目标位置，然后相对于移位地标（相同或相反的视野）进行到达。为了使任务之间的运动执行相等，参与者被指示在 50%的自我中心试验中进行反向指向（指向记忆目标的相反视野）。参与者在非自我中心条件下的准确性、精度和反应速度更快，尤其是在指向相反的视野时。我们还观察到了视野效应，即整体表现右眼视野较差。这些结果表明，当自我中心和非自我中心线索冲突时，明确使用视觉地标比依赖嘈杂的自我中心信号提供更好的到达性能。当自我中心系统因疾病或损伤而受损时，这种指示可能有助于康复。
