心理科学

心理科学 ›› 2012, Vol. 35 ›› Issue (6): 1338-1342.

• 基础、实验与工效 • 上一篇    下一篇

周边视觉的知觉学习

徐笑含,谢新秀,邵志芳   

  1. 华东师范大学
  • 收稿日期:2011-11-04 修回日期:2012-02-20 出版日期:2012-11-20 发布日期:2012-11-20
  • 通讯作者: 邵志芳

Perceptual Learning of Peripheral Vision

  • Received:2011-11-04 Revised:2012-02-20 Online:2012-11-20 Published:2012-11-20

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摘要：

知觉学习是指知觉能力随着知觉训练或经验逐渐改变的现象。它具有特异性-迁移性，可以根据时程划分为快速学习和慢速学习。知觉学习意味着与知觉直接对应的脑区神经元激活方式的变化，并且与注意有着一定的联系。目前周边视觉的知觉学习研究已有一些成果：对于非语词刺激，随着练习，判断目标刺激（例如刺激朝向、游标视敏度）的能力，有很大的提升；对于语词刺激，周边视觉的知觉学习可以帮助提高阅读速度。可以通过提高视觉广度来提高周边视觉的阅读速度。周边视觉的知觉学习还有着重大应用价值，可以帮助中央凹视觉缺损的人们提高周边视觉能力，帮助恢复阅读能力。

关键词: 周边视觉, 神经机制, 知觉学习, 视觉广度, 阅读

Abstract:

Perceptual learning is defined as improvement of the performance on perceptual tasks after training. Perceptual learning of human visual system has been widely investigated. Previous studies on perceptual learning were focused on its specificity and generalization. In some visual tasks, such as retinal location, spatial frequency or orientation, the learned performance is limited to the specific stimulus. In some other visual tasks, the improved performance can be transferred to different stimulus or tasks. Specificity and generalization can be viewed as two ends of a transferability continuum, on which each task may have a specific position (or value). Neurophysiological findings suggested that perceptual learning of different complexities may involve different levels of visual cortical processing, and the neural mechanism involved may depend on the feature (e.g., the complexity) of the stimulus in the task. Perceptual learning can be divided into fast learning and slow learning. A number of studies have used ERP and other brain imaging techniques to investigate the neural mechanism of visual perceptual learning under different time scales. Age-related macular degeneration (AMD) afflicts about 10% Americans aged over 80 years. The patients often feel bilateral central scotoma, because AMD damaged their fovea. Because reading is slow and difficult for these patients, they have to use their peripheral retina. In order to help these patients improve their reading, many researches focused on perceptual learning of peripheral vision. A research suggested that training on a letter-recognition task would lead young adults to improve reading speed in peripheral vision, and this learning effect would transfer to an untrained retinal location. For olds, researches showed that reading speed also improved in the trained field, but the training benefits for these old adults were weaker than the training benefits for young adults. Perceptual learning is still a potential method for low-vision reading rehabilitation among older adults, despite the training benefits is weaker. Some studies suggested a link between reading speed and the size of the visual span. Visual span means the number of characters that can be recognized on a single fixation. It is a bottleneck on reading speed, but it can be increased with practice. A study about comparing reading speed for vertical and horizontal English text using RSVP and flashcard (a block of text on four lines) showed that reading speed for horizontal text was faster. Size of the visual span was highly correlated with reading speed, both for RSVP and flashcard reading. It shows that slower reading of vertical text is due to a decrease in the size of the visual span for vertical reading. The RSVP reading and lexical-decision might plausibly produce more improvement in peripheral reading speed. Chinese character is important for any Chinese reader. Its perceptual learning of peripheral vision is an interesting research field of great value, but the paradigm should be improved.

Key words: peripheral vision, neural mechanism, perceptual leaning, visual span, reading