Olkoniemi Henri, Hurme Mikko, Railo Henry
Division of Psychology, Faculty of Education and Psychology, University of Oulu, Finland; Department of Psychology and Speech Language Pathology, University of Turku, Finland.
Department of Psychology and Speech Language Pathology, University of Turku, Finland; Turku Brain and Mind Centre, University of Turku, Finland.
Neuroscience. 2023 Mar 1;513:111-125. doi: 10.1016/j.neuroscience.2023.01.014. Epub 2023 Jan 23.
Some patients with a visual field loss due to a lesion in the primary visual cortex (V1) can shift their gaze to stimuli presented in their blind visual field. The extent to which a similar "blindsight" capacity is present in neurologically healthy individuals remains unknown. Using retinotopically navigated transcranial magnetic stimulation (TMS) of V1 (Experiment 1) and metacontrast masking (Experiment 2) to suppress conscious vision, we examined neurologically healthy humans' ability to make saccadic eye movements toward visual targets that they reported not seeing. In the TMS experiment, the participants were more likely to initiate a saccade when a stimulus was presented, and they reported not seeing it, than in trials which no stimulus was presented. However, this happened only in a very small proportion (∼8%) of unseen trials, suggesting that saccadic reactions were largely based on conscious perception. In both experiments, saccade landing location was influenced by unconscious information: When the participants denied seeing the target but made a saccade, the saccade was made toward the correct location (TMS: 68%, metacontrast: 63%) more often than predicted by chance. Signal detection theoretic measures suggested that in the TMS experiment, saccades toward unseen targets may have been based on weak conscious experiences. In both experiments, reduced visibility of the target stimulus was associated with slower and less precise gaze shifts. These results suggest that saccades made by neurologically healthy humans may be influenced by unconscious information, although the initiation of saccades is largely based on conscious vision.
一些因初级视觉皮层（V1）损伤而出现视野缺损的患者能够将目光转向出现在其盲视野中的刺激物。在神经功能正常的个体中，类似的“盲视”能力存在的程度尚不清楚。我们利用V1的视网膜定位导航经颅磁刺激（实验1）和元对比掩蔽（实验2）来抑制有意识视觉，研究了神经功能正常的人对他们报告未看到的视觉目标进行扫视眼动的能力。在经颅磁刺激实验中，与未呈现刺激的试验相比，当呈现刺激且参与者报告未看到时，他们更有可能发起扫视。然而，这种情况仅发生在极小比例（约8%）的未看到试验中，这表明扫视反应在很大程度上基于有意识感知。在两个实验中，扫视着陆位置都受到无意识信息的影响：当参与者否认看到目标但进行了扫视时，扫视朝着正确位置（经颅磁刺激：68%，元对比：63%）的情况比随机预测的更频繁。信号检测理论测量表明，在经颅磁刺激实验中，朝着未看到目标的扫视可能基于微弱的有意识体验。在两个实验中，目标刺激的可见度降低与较慢且不太精确的目光转移相关。这些结果表明，神经功能正常的人做出的扫视可能受到无意识信息的影响，尽管扫视的发起在很大程度上基于有意识视觉。
