Department of Ophthalmology, The Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, 20 Staniford Street, Boston, MA 02114-2500, United States of America. School of Psychology, University of Sydney, Sydney, Australia.
J Neural Eng. 2018 Oct;15(5):055003. doi: 10.1088/1741-2552/aac663. Epub 2018 May 21.
Evaluations of vision prostheses and sensory substitution devices have frequently relied on repeated training and then testing with the same small set of items. These multiple forced-choice tasks produced above chance performance in blind users, but it is unclear if the observed performance represents restoration of vision that transfers to novel, untrained items.
Here, we tested the generalizability of the forced-choice paradigm on discrimination of low-resolution word images. Extensive visual training was conducted with the same 10 words used in previous BrainPort tongue stimulation studies. The performance on these 10 words and an additional 50 words was measured before and after the training sessions.
The results revealed minimal performance improvement with the untrained words, demonstrating instead pattern discrimination limited mostly to the trained words.
These findings highlight the need to reconsider current evaluation practices, in particular, the use of forced-choice paradigms with a few highly trained items. While appropriate for measuring the performance thresholds in acuity or contrast sensitivity of a functioning visual system, performance on such tasks cannot be taken to indicate restored spatial pattern vision.
评估视觉假体和感觉替代设备的方法通常依赖于对同一小数据集进行多次重复训练和测试。这些多项强制选择任务使盲用者的表现超出了机会水平，但尚不清楚观察到的表现是否代表了可转移到新的、未经训练的项目的视觉恢复。
在这里，我们测试了强制选择范式在低分辨率单词图像识别中的泛化能力。使用之前在 BrainPort 舌刺激研究中使用的相同的 10 个单词进行了广泛的视觉训练。在训练前后测量了这些 10 个单词和另外 50 个单词的表现。
结果显示，未训练的单词的表现仅略有提高，这表明模式识别主要局限于已训练的单词。
这些发现强调了需要重新考虑当前的评估实践，特别是使用少数经过高度训练的项目的强制选择范式。虽然强制选择范式适合测量功能视觉系统的敏锐度或对比敏感度的性能阈值，但此类任务的表现不能表明恢复了空间模式视觉。
