On the afternoon of June 27, Dr. Ming Yan, Associate Professor in the Department of Psychology at the University of Macau and Research Fellow at the Zhuhai Institute of the University of Macau, delivered a lecture titled “The Perceptual Span in Reading: A Cross-Linguistic Comparison.”Using eye-tracking technology, Dr. Yan explored the core mechanism underlying human reading—perceptual span—and compared cognitive differences across multiple languages, including Chinese, English, Tibetan, and Uyghur.
Reading is inherently a discontinuous, jump-based process. Rather than scanning text smoothly, readers acquire information through a cycle of brief fixations (lasting 200–400 milliseconds) followed by rapid saccades. Only about two degrees of visual angle—the width of roughly one Chinese character—can be seen with high clarity at the center of gaze, while peripheral information must be integrated through working memory.
A key feature of this process is the asymmetry of perceptual span, which varies across languages:
●Chinese: 1 character to the left + 4 characters to the right
●English: 4 letters to the left + 15 letters to the right
●Tibetan: 3 characters to the left + 7–8 characters to the right
●Uyghur (right-to-left script): 11–12 letters to the left + 4–5 letters to the right
These findings challenge the traditional “left-hemisphere dominance” theory by showing that reading direction, rather than brain lateralization, primarily shapes how attentional resources are distributed. One central discovery is the consistent rightward asymmetry of perceptual span in left-to-right reading languages (e.g., Chinese, English, Tibetan), where readers extract more information to the right of the fixation point. This has long been attributed to the left hemisphere’s specialization for language, which directly receives input from the right visual field.
However, research on Uyghur provides a critical counterexample. As a right-to-left script, Uyghur readers demonstrate a reversed asymmetry in perceptual span: the left side of the fixation point—corresponding to the direction of upcoming, unread text—shows a significantly wider span. This strongly supports the attentional resource allocation theory, which proposes that readers tend to devote more attention to the forward direction of reading (where new information is expected), rather than the asymmetry being determined by hemispheric lateralization. This finding effectively falsifies the traditional “left-hemisphere language dominance” hypothesis.
Additional findings include structural insights from Tibetan script, where the position of core syllabic components influences the efficiency of visual information extraction. Furthermore, reading orientation plays a critical role in perceptual span. For readers accustomed to horizontal text, the perceptual span extends to about four characters below the fixation point; for those more familiar with vertical reading formats, it shifts to approximately three characters. Notably, highly experienced vertical readers can develop even greater downward spans. These results demonstrate the plasticity of perceptual span and suggest that vertical reading layouts can be just as efficient once fully internalized.
Dr. Ming Yan’s lecture vividly illustrated the mechanisms of perceptual span in reading through a systematic cross-linguistic (Chinese, English, Tibetan, Uyghur) and cross-population (adults, children, skilled readers, and readers with difficulties) comparison. The findings underscore that the core mechanism shaping perceptual span is the allocation of attentional resources, with reading direction determining the direction of asymmetry.In addition, the visual properties of written scripts—such as character density and complexity—play a critical role in shaping the overall size of the span. The lecture also highlighted significant individual differences in perceptual span, influenced by age, reading ability, and prior experience, all of which carry important implications for education and reading intervention.
