Participants

The relevant Research Ethics committee of Beijing Normal University approved this study. Written informed consent was obtained from the parents of all of the children before the study. Typically, visually impaired students are placed in special schools in China. These schools cater to both low-vision and blind students. Most low-vision students cannot print read even with eyesight-aiding devices, and only Braille is used in teaching and learning. One hundred and forty-two blind students were recruited from two urban special schools in the Hunan and Zhejiang provinces of China. Specifically, the blind participants consisted of 11 children (8 males) in grade 1, 24 children (13 males) in grade 2, 22 children (15 males) in grade 3, 24 children (13 males) in grade 4, 24 children (13 males) in grade 5, and 48 children (24 males) in grade 6. All students were native speakers of Chinese and had normal hearing and intelligence based on feedback collected from teachers and parents. To investigate developmental patterns, the blind participants comprised two groups: (1) blind children in lower grades of primary school, including 57 blind students across grades 1 to 3 (mean age = 131.39 months), two of whom still perceive light, but the others have no remaining rest vision; and (2) blind children in higher grades of the primary school including 85 blind students across grades 4 to 6 (mean age = 172.47 months), three of whom do still perceive light, whereas the others have no remaining rest vision.