Vision and Attention Laboratories, School of Psychology, College of Life Sciences and Medicine, King's College, University of Aberdeen, Aberdeen, United Kingdom.
Invest Ophthalmol Vis Sci. 2013 May 1;54(5):3579-85. doi: 10.1167/iovs.12-11231.
We investigated systematically the effect of repeated exposure on detection and reported awareness of visual stimuli presented deep within the field defect of 5 hemianopic patients.
An objective measure of sensitivity (detection in a temporal two-alternative forced-choice paradigm) and subjective reports of awareness were recorded on trial by trial bases. Visual stimulus to be detected was a temporally modulated (10 Hz) circular patch (6° diameter) of vertical grating (1 c/°). Hemianopic patients took part in the study 8 to 15 months after injury, so that the findings could not be attributed to spontaneous recovery.
Initially, high contrast (90%) target stimuli were detected at or near chance level with little reported awareness. In 4 of 5 cases, repeated stimulation led to improved sensitivity, indicated by increased detection scores and higher incidence of awareness. In a fifth case, there was no change in sensitivity despite extensive exposure (>22,000 trials).
At retinal locations deep within the field defect, repeated stimulation can lead to blindsight performance (type I detection without awareness), followed by detection with reported awareness (type II blindsight), and eventual reported visual experiences. The findings indicate that conscious awareness of stimuli lies on a continuous spectrum and repeated systematic training can lead to improved visual sensitivity.
我们系统地研究了重复暴露对 5 名偏盲患者视野缺损深处呈现的视觉刺激的检测和报告意识的影响。
在逐个试验的基础上，记录了一种客观的敏感性测量方法（在时间双选择强制选择范式中的检测）和主观报告的意识。要检测的视觉刺激是一个时间调制（10 Hz）的圆形斑块（6°直径）的垂直光栅（1 c /°）。偏盲患者在受伤后 8 到 15 个月参加了这项研究，因此这些发现不能归因于自发恢复。
最初，高对比度（90%）目标刺激的检测率接近或接近机会水平，且报告的意识很少。在 5 例中有 4 例，重复刺激导致敏感性提高，表现为检测分数提高和意识发生率提高。在第五例中，尽管进行了广泛的暴露（>22,000 次试验），但敏感性没有变化。
在视网膜位置深处的视野缺损处，重复刺激可以导致盲视表现（无意识的 I 型检测），随后是有意识的检测（II 型盲视），并最终出现有报告的视觉体验。研究结果表明，意识对刺激的感知位于连续光谱上，反复的系统训练可以提高视觉敏感性。
